From b803359ce96ee4a705c04a56e0e90d4e946e1805 Mon Sep 17 00:00:00 2001
From: Aaron Clarke <aaclarke@google.com>
Date: Mon, 8 Jan 2024 11:19:08 -0800
Subject: [PATCH 01/28] [Impeller] new blur: added mipmap generation

---
 .../contents/filters/gaussian_blur_filter_contents.cc | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/impeller/entity/contents/filters/gaussian_blur_filter_contents.cc b/impeller/entity/contents/filters/gaussian_blur_filter_contents.cc
index c83f0e0d79647..cc8aa2d529231 100644
--- a/impeller/entity/contents/filters/gaussian_blur_filter_contents.cc
+++ b/impeller/entity/contents/filters/gaussian_blur_filter_contents.cc
@@ -284,6 +284,17 @@ std::optional<Entity> GaussianBlurFilterContents::RenderFilter(
                                 entity.GetClipDepth());  // No blur to render.
   }
 
+  if (!input_snapshot.value().texture->NeedsMipmapGeneration() &&
+      input_snapshot.value().texture->GetMipCount() <= 1) {
+    std::shared_ptr<CommandBuffer> mip_cmd_buffer =
+        renderer.GetContext()->CreateCommandBuffer();
+    std::shared_ptr<BlitPass> blit_pass = mip_cmd_buffer->CreateBlitPass();
+    blit_pass->GenerateMipmap(input_snapshot.value().texture);
+    blit_pass->EncodeCommands(renderer.GetContext()->GetResourceAllocator());
+    bool success = mip_cmd_buffer->SubmitCommands(/*callback=*/nullptr);
+    FML_CHECK(success);
+  }
+
   Scalar desired_scalar =
       std::min(CalculateScale(scaled_sigma.x), CalculateScale(scaled_sigma.y));
   // TODO(jonahwilliams): If desired_scalar is 1.0 and we fully acquired the

From 6f20569e8cd2afee701de6907bd55e72a7f401f7 Mon Sep 17 00:00:00 2001
From: Aaron Clarke <aaclarke@google.com>
Date: Mon, 8 Jan 2024 13:31:16 -0800
Subject: [PATCH 02/28] added lod parameter

---
 .../contents/filters/gaussian_blur_filter_contents.cc     | 2 ++
 .../contents/filters/gaussian_blur_filter_contents.h      | 1 +
 .../filters/gaussian_blur_filter_contents_unittests.cc    | 5 ++++-
 impeller/entity/shaders/gaussian_blur/kernel.glsl         | 8 +++++---
 4 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/impeller/entity/contents/filters/gaussian_blur_filter_contents.cc b/impeller/entity/contents/filters/gaussian_blur_filter_contents.cc
index cc8aa2d529231..ba41c985ea0be 100644
--- a/impeller/entity/contents/filters/gaussian_blur_filter_contents.cc
+++ b/impeller/entity/contents/filters/gaussian_blur_filter_contents.cc
@@ -364,6 +364,7 @@ std::optional<Entity> GaussianBlurFilterContents::RenderFilter(
           .blur_radius =
               static_cast<int>(std::round(blur_radius.y * effective_scalar.y)),
           .step_size = 1,
+          .lod = -1,
       },
       /*destination_target=*/std::nullopt, blur_uvs);
 
@@ -446,6 +447,7 @@ Scalar GaussianBlurFilterContents::ScaleSigma(Scalar sigma) {
 KernelPipeline::FragmentShader::KernelSamples GenerateBlurInfo(
     BlurParameters parameters) {
   KernelPipeline::FragmentShader::KernelSamples result;
+  result.lod = parameters.lod;
   result.sample_count =
       ((2 * parameters.blur_radius) / parameters.step_size) + 1;
   // 32 comes from kernel.glsl.
diff --git a/impeller/entity/contents/filters/gaussian_blur_filter_contents.h b/impeller/entity/contents/filters/gaussian_blur_filter_contents.h
index 1bb594f3e4ae6..fdcd9ba3a6143 100644
--- a/impeller/entity/contents/filters/gaussian_blur_filter_contents.h
+++ b/impeller/entity/contents/filters/gaussian_blur_filter_contents.h
@@ -16,6 +16,7 @@ struct BlurParameters {
   Scalar blur_sigma;
   int blur_radius;
   int step_size;
+  Scalar lod;
 };
 
 KernelPipeline::FragmentShader::KernelSamples GenerateBlurInfo(
diff --git a/impeller/entity/contents/filters/gaussian_blur_filter_contents_unittests.cc b/impeller/entity/contents/filters/gaussian_blur_filter_contents_unittests.cc
index ba3053483181f..c2dddf4052c07 100644
--- a/impeller/entity/contents/filters/gaussian_blur_filter_contents_unittests.cc
+++ b/impeller/entity/contents/filters/gaussian_blur_filter_contents_unittests.cc
@@ -462,7 +462,8 @@ TEST(GaussianBlurFilterContentsTest, Coefficients) {
   BlurParameters parameters = {.blur_uv_offset = Point(1, 0),
                                .blur_sigma = 1,
                                .blur_radius = 5,
-                               .step_size = 1};
+                               .step_size = 1,
+                               .lod = -1.f};
   KernelPipeline::FragmentShader::KernelSamples samples =
       GenerateBlurInfo(parameters);
   EXPECT_EQ(samples.sample_count, 9);
@@ -481,6 +482,8 @@ TEST(GaussianBlurFilterContentsTest, Coefficients) {
     EXPECT_TRUE(samples.samples[i + 1].coefficient >
                 samples.samples[i].coefficient);
   }
+
+  EXPECT_FLOAT_EQ(samples.lod, -1.f);
 }
 
 }  // namespace testing
diff --git a/impeller/entity/shaders/gaussian_blur/kernel.glsl b/impeller/entity/shaders/gaussian_blur/kernel.glsl
index d8a544bf070f6..1b0ca6ae174a7 100644
--- a/impeller/entity/shaders/gaussian_blur/kernel.glsl
+++ b/impeller/entity/shaders/gaussian_blur/kernel.glsl
@@ -17,14 +17,15 @@ struct KernelSample {
 uniform KernelSamples {
   int sample_count;
   KernelSample samples[32];
+  float lod;
 }
 blur_info;
 
-f16vec4 Sample(f16sampler2D tex, vec2 coords) {
+f16vec4 Sample(f16sampler2D tex, vec2 coords, float lod) {
 #if ENABLE_DECAL_SPECIALIZATION
   return IPHalfSampleDecal(tex, coords);
 #else
-  return texture(tex, coords);
+  return texture(tex, coords, lod);
 #endif
 }
 
@@ -39,7 +40,8 @@ void main() {
     float16_t coefficient = float16_t(blur_info.samples[i].coefficient);
     total_color +=
         coefficient * Sample(texture_sampler,
-                             v_texture_coords + blur_info.samples[i].uv_offset);
+                             v_texture_coords + blur_info.samples[i].uv_offset,
+                             blur_info.lod);
   }
 
   frag_color = total_color;

From 92859a26e4c0f8d8f27aae810e8b48c61ad92231 Mon Sep 17 00:00:00 2001
From: Aaron Clarke <aaclarke@google.com>
Date: Mon, 8 Jan 2024 13:45:44 -0800
Subject: [PATCH 03/28] started sending the correct lod

---
 .../contents/filters/gaussian_blur_filter_contents.cc      | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/impeller/entity/contents/filters/gaussian_blur_filter_contents.cc b/impeller/entity/contents/filters/gaussian_blur_filter_contents.cc
index ba41c985ea0be..9575937997cff 100644
--- a/impeller/entity/contents/filters/gaussian_blur_filter_contents.cc
+++ b/impeller/entity/contents/filters/gaussian_blur_filter_contents.cc
@@ -193,6 +193,9 @@ Rect MakeReferenceUVs(const Rect& reference, const Rect& rect) {
   return result.Scale(1.0f / Vector2(reference.GetSize()));
 }
 
+Scalar CalculateLOD(Scalar scalar) {
+  return fabsf(log2f(1.f / scalar));
+}
 }  // namespace
 
 GaussianBlurFilterContents::GaussianBlurFilterContents(
@@ -297,6 +300,7 @@ std::optional<Entity> GaussianBlurFilterContents::RenderFilter(
 
   Scalar desired_scalar =
       std::min(CalculateScale(scaled_sigma.x), CalculateScale(scaled_sigma.y));
+  Scalar lod = CalculateLOD(desired_scalar);
   // TODO(jonahwilliams): If desired_scalar is 1.0 and we fully acquired the
   // gutter from the expanded_coverage_hint, we can skip the downsample pass.
   // pass.
@@ -364,7 +368,7 @@ std::optional<Entity> GaussianBlurFilterContents::RenderFilter(
           .blur_radius =
               static_cast<int>(std::round(blur_radius.y * effective_scalar.y)),
           .step_size = 1,
-          .lod = -1,
+          .lod = lod,
       },
       /*destination_target=*/std::nullopt, blur_uvs);
 
@@ -387,6 +391,7 @@ std::optional<Entity> GaussianBlurFilterContents::RenderFilter(
           .blur_radius =
               static_cast<int>(std::round(blur_radius.x * effective_scalar.x)),
           .step_size = 1,
+          .lod = lod,
       },
       pass3_destination, blur_uvs);
 

From 48522bb7ea580138574cb3d64b9e269bfab0524b Mon Sep 17 00:00:00 2001
From: Aaron Clarke <aaclarke@google.com>
Date: Mon, 8 Jan 2024 13:51:30 -0800
Subject: [PATCH 04/28] textureLod

---
 impeller/entity/shaders/gaussian_blur/kernel.glsl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/impeller/entity/shaders/gaussian_blur/kernel.glsl b/impeller/entity/shaders/gaussian_blur/kernel.glsl
index 1b0ca6ae174a7..7a6ff6f376d56 100644
--- a/impeller/entity/shaders/gaussian_blur/kernel.glsl
+++ b/impeller/entity/shaders/gaussian_blur/kernel.glsl
@@ -25,7 +25,7 @@ f16vec4 Sample(f16sampler2D tex, vec2 coords, float lod) {
 #if ENABLE_DECAL_SPECIALIZATION
   return IPHalfSampleDecal(tex, coords);
 #else
-  return texture(tex, coords, lod);
+  return textureLod(tex, coords, lod);
 #endif
 }
 

From 7b248f79642dd1f29dd78e293f8e6154b0817b86 Mon Sep 17 00:00:00 2001
From: Aaron Clarke <aaclarke@google.com>
Date: Mon, 8 Jan 2024 16:14:25 -0800
Subject: [PATCH 05/28] hack to set mip level to 4

---
 impeller/aiks/picture.cc                      |  1 +
 .../checkerboard_contents_unittests.cc        |  3 ++-
 impeller/entity/contents/content_context.cc   |  2 +-
 .../filters/gaussian_blur_filter_contents.cc  |  3 +--
 .../tiled_texture_contents_unittests.cc       |  3 ++-
 .../contents/vertices_contents_unittests.cc   |  3 ++-
 impeller/entity/entity_pass.cc                | 24 +++++++++++--------
 .../entity/entity_pass_target_unittests.cc    |  3 ++-
 impeller/renderer/render_target.cc            |  2 ++
 impeller/renderer/render_target.h             |  1 +
 10 files changed, 28 insertions(+), 17 deletions(-)

diff --git a/impeller/aiks/picture.cc b/impeller/aiks/picture.cc
index ea07dfd27a58c..bd32f9068f895 100644
--- a/impeller/aiks/picture.cc
+++ b/impeller/aiks/picture.cc
@@ -64,6 +64,7 @@ std::shared_ptr<Texture> Picture::RenderToTexture(
         *impeller_context,        // context
         render_target_allocator,  // allocator
         size,                     // size
+        /*mip_count=*/1,
         "Picture Snapshot MSAA",  // label
         RenderTarget::
             kDefaultColorAttachmentConfigMSAA,  // color_attachment_config
diff --git a/impeller/entity/contents/checkerboard_contents_unittests.cc b/impeller/entity/contents/checkerboard_contents_unittests.cc
index 46328620026b6..63a2cbdd3aa07 100644
--- a/impeller/entity/contents/checkerboard_contents_unittests.cc
+++ b/impeller/entity/contents/checkerboard_contents_unittests.cc
@@ -35,7 +35,8 @@ TEST_P(EntityTest, RendersWithoutError) {
   auto buffer = content_context->GetContext()->CreateCommandBuffer();
   auto render_target = RenderTarget::CreateOffscreenMSAA(
       *content_context->GetContext(),
-      *GetContentContext()->GetRenderTargetCache(), {100, 100});
+      *GetContentContext()->GetRenderTargetCache(), {100, 100},
+      /*mip_count=*/1);
   auto render_pass = buffer->CreateRenderPass(render_target);
   Entity entity;
 
diff --git a/impeller/entity/contents/content_context.cc b/impeller/entity/contents/content_context.cc
index 634ae0b8e6fa7..6cd649eaa582d 100644
--- a/impeller/entity/contents/content_context.cc
+++ b/impeller/entity/contents/content_context.cc
@@ -418,7 +418,7 @@ fml::StatusOr<RenderTarget> ContentContext::MakeSubpass(
   RenderTarget subpass_target;
   if (context->GetCapabilities()->SupportsOffscreenMSAA() && msaa_enabled) {
     subpass_target = RenderTarget::CreateOffscreenMSAA(
-        *context, *GetRenderTargetCache(), texture_size,
+        *context, *GetRenderTargetCache(), texture_size, /*mip_count=*/1,
         SPrintF("%s Offscreen", label.c_str()),
         RenderTarget::kDefaultColorAttachmentConfigMSAA,
         std::nullopt  // stencil_attachment_config
diff --git a/impeller/entity/contents/filters/gaussian_blur_filter_contents.cc b/impeller/entity/contents/filters/gaussian_blur_filter_contents.cc
index 9575937997cff..5ac0ec0035142 100644
--- a/impeller/entity/contents/filters/gaussian_blur_filter_contents.cc
+++ b/impeller/entity/contents/filters/gaussian_blur_filter_contents.cc
@@ -287,8 +287,7 @@ std::optional<Entity> GaussianBlurFilterContents::RenderFilter(
                                 entity.GetClipDepth());  // No blur to render.
   }
 
-  if (!input_snapshot.value().texture->NeedsMipmapGeneration() &&
-      input_snapshot.value().texture->GetMipCount() <= 1) {
+  if (input_snapshot.value().texture->NeedsMipmapGeneration()) {
     std::shared_ptr<CommandBuffer> mip_cmd_buffer =
         renderer.GetContext()->CreateCommandBuffer();
     std::shared_ptr<BlitPass> blit_pass = mip_cmd_buffer->CreateBlitPass();
diff --git a/impeller/entity/contents/tiled_texture_contents_unittests.cc b/impeller/entity/contents/tiled_texture_contents_unittests.cc
index 2060f23437c2f..8fc5fecd99fb7 100644
--- a/impeller/entity/contents/tiled_texture_contents_unittests.cc
+++ b/impeller/entity/contents/tiled_texture_contents_unittests.cc
@@ -33,7 +33,8 @@ TEST_P(EntityTest, TiledTextureContentsRendersWithCorrectPipeline) {
   auto buffer = content_context->GetContext()->CreateCommandBuffer();
   auto render_target = RenderTarget::CreateOffscreenMSAA(
       *content_context->GetContext(),
-      *GetContentContext()->GetRenderTargetCache(), {100, 100});
+      *GetContentContext()->GetRenderTargetCache(), {100, 100},
+      /*mip_count=*/1);
   auto render_pass = buffer->CreateRenderPass(render_target);
 
   ASSERT_TRUE(contents.Render(*GetContentContext(), {}, *render_pass));
diff --git a/impeller/entity/contents/vertices_contents_unittests.cc b/impeller/entity/contents/vertices_contents_unittests.cc
index 173b13ea4bcfb..17fac72d722dc 100644
--- a/impeller/entity/contents/vertices_contents_unittests.cc
+++ b/impeller/entity/contents/vertices_contents_unittests.cc
@@ -61,7 +61,8 @@ TEST_P(EntityTest, RendersDstPerColorWithAlpha) {
   auto buffer = content_context->GetContext()->CreateCommandBuffer();
   auto render_target = RenderTarget::CreateOffscreenMSAA(
       *content_context->GetContext(),
-      *GetContentContext()->GetRenderTargetCache(), {100, 100});
+      *GetContentContext()->GetRenderTargetCache(), {100, 100},
+      /*mip_count=*/1);
   auto render_pass = buffer->CreateRenderPass(render_target);
   Entity entity;
 
diff --git a/impeller/entity/entity_pass.cc b/impeller/entity/entity_pass.cc
index 67e343de8a6d5..aad8bd396a883 100644
--- a/impeller/entity/entity_pass.cc
+++ b/impeller/entity/entity_pass.cc
@@ -247,6 +247,7 @@ static const constexpr RenderTarget::AttachmentConfig kDefaultStencilConfig =
 
 static EntityPassTarget CreateRenderTarget(ContentContext& renderer,
                                            ISize size,
+                                           int mip_count,
                                            const Color& clear_color) {
   auto context = renderer.GetContext();
 
@@ -258,18 +259,20 @@ static EntityPassTarget CreateRenderTarget(ContentContext& renderer,
   RenderTarget target;
   if (context->GetCapabilities()->SupportsOffscreenMSAA()) {
     target = RenderTarget::CreateOffscreenMSAA(
-        *context,                          // context
-        *renderer.GetRenderTargetCache(),  // allocator
-        size,                              // size
-        "EntityPass",                      // label
+        /*context=*/*context,
+        /*allocator=*/*renderer.GetRenderTargetCache(),
+        /*size=*/size,
+        /*mip_count=*/mip_count,
+        /*label=*/"EntityPass",
+        /*color_attachment_config=*/
         RenderTarget::AttachmentConfigMSAA{
             .storage_mode = StorageMode::kDeviceTransient,
             .resolve_storage_mode = StorageMode::kDevicePrivate,
             .load_action = LoadAction::kDontCare,
             .store_action = StoreAction::kMultisampleResolve,
-            .clear_color = clear_color},  // color_attachment_config
-        kDefaultStencilConfig             // stencil_attachment_config
-    );
+            .clear_color = clear_color},
+        /*stencil_attachment_config=*/
+        kDefaultStencilConfig);
   } else {
     target = RenderTarget::CreateOffscreen(
         *context,                          // context
@@ -339,7 +342,7 @@ bool EntityPass::Render(ContentContext& renderer,
   // there's no need to set up a stencil attachment on the root render target.
   if (reads_from_onscreen_backdrop) {
     auto offscreen_target = CreateRenderTarget(
-        renderer, root_render_target.GetRenderTargetSize(),
+        renderer, root_render_target.GetRenderTargetSize(), /*mip_count=*/4,
         GetClearColorOrDefault(render_target.GetRenderTargetSize()));
 
     if (!OnRender(renderer,  // renderer
@@ -599,8 +602,9 @@ EntityPass::EntityResult EntityPass::GetEntityForElement(
     }
 
     auto subpass_target = CreateRenderTarget(
-        renderer,                                        // renderer
-        subpass_size,                                    // size
+        renderer,      // renderer
+        subpass_size,  // size
+        /*mip_count=*/1,
         subpass->GetClearColorOrDefault(subpass_size));  // clear_color
 
     if (!subpass_target.IsValid()) {
diff --git a/impeller/entity/entity_pass_target_unittests.cc b/impeller/entity/entity_pass_target_unittests.cc
index 390f7929913f7..108da36230506 100644
--- a/impeller/entity/entity_pass_target_unittests.cc
+++ b/impeller/entity/entity_pass_target_unittests.cc
@@ -26,7 +26,8 @@ TEST_P(EntityPassTargetTest, SwapWithMSAATexture) {
   auto buffer = content_context->GetContext()->CreateCommandBuffer();
   auto render_target = RenderTarget::CreateOffscreenMSAA(
       *content_context->GetContext(),
-      *GetContentContext()->GetRenderTargetCache(), {100, 100});
+      *GetContentContext()->GetRenderTargetCache(), {100, 100},
+      /*mip_count=*/1);
 
   auto entity_pass_target = EntityPassTarget(render_target, false, false);
 
diff --git a/impeller/renderer/render_target.cc b/impeller/renderer/render_target.cc
index 3a9f1e0468e81..f2aca7f44d5d2 100644
--- a/impeller/renderer/render_target.cc
+++ b/impeller/renderer/render_target.cc
@@ -266,6 +266,7 @@ RenderTarget RenderTarget::CreateOffscreenMSAA(
     const Context& context,
     RenderTargetAllocator& allocator,
     ISize size,
+    int mip_count,
     const std::string& label,
     AttachmentConfigMSAA color_attachment_config,
     std::optional<AttachmentConfig> stencil_attachment_config) {
@@ -310,6 +311,7 @@ RenderTarget RenderTarget::CreateOffscreenMSAA(
   color0_resolve_tex_desc.usage =
       static_cast<uint64_t>(TextureUsage::kRenderTarget) |
       static_cast<uint64_t>(TextureUsage::kShaderRead);
+  color0_resolve_tex_desc.mip_count = mip_count;
 
   auto color0_resolve_tex = allocator.CreateTexture(color0_resolve_tex_desc);
   if (!color0_resolve_tex) {
diff --git a/impeller/renderer/render_target.h b/impeller/renderer/render_target.h
index dbd115a5c7612..388cfb7029fa8 100644
--- a/impeller/renderer/render_target.h
+++ b/impeller/renderer/render_target.h
@@ -95,6 +95,7 @@ class RenderTarget final {
       const Context& context,
       RenderTargetAllocator& allocator,
       ISize size,
+      int mip_count,
       const std::string& label = "Offscreen MSAA",
       AttachmentConfigMSAA color_attachment_config =
           kDefaultColorAttachmentConfigMSAA,

From cd3136d5f6d0d97a857e3e631c13cfa6863182ba Mon Sep 17 00:00:00 2001
From: Aaron Clarke <aaclarke@google.com>
Date: Tue, 9 Jan 2024 10:10:18 -0800
Subject: [PATCH 06/28] started invalidating mipmaps

---
 impeller/core/texture.cc                                   | 4 ++++
 impeller/core/texture.h                                    | 2 ++
 impeller/entity/contents/filters/filter_contents.cc        | 2 ++
 .../contents/filters/gaussian_blur_filter_contents.cc      | 1 +
 impeller/entity/entity_pass.cc                             | 7 +++++++
 impeller/renderer/backend/metal/texture_mtl.mm             | 2 ++
 impeller/renderer/render_target.cc                         | 4 ++++
 7 files changed, 22 insertions(+)

diff --git a/impeller/core/texture.cc b/impeller/core/texture.cc
index bb2f125aea503..f8ba083783700 100644
--- a/impeller/core/texture.cc
+++ b/impeller/core/texture.cc
@@ -86,4 +86,8 @@ bool Texture::NeedsMipmapGeneration() const {
   return !mipmap_generated_ && desc_.mip_count > 1;
 }
 
+void Texture::InvalidateMipmap() {
+  mipmap_generated_ = false;
+}
+
 }  // namespace impeller
diff --git a/impeller/core/texture.h b/impeller/core/texture.h
index b28dbb27ab5f3..d0bcc40432062 100644
--- a/impeller/core/texture.h
+++ b/impeller/core/texture.h
@@ -47,6 +47,8 @@ class Texture {
 
   bool NeedsMipmapGeneration() const;
 
+  void InvalidateMipmap();
+
  protected:
   explicit Texture(TextureDescriptor desc);
 
diff --git a/impeller/entity/contents/filters/filter_contents.cc b/impeller/entity/contents/filters/filter_contents.cc
index 5f2c310f78d9e..c4ffaff85726d 100644
--- a/impeller/entity/contents/filters/filter_contents.cc
+++ b/impeller/entity/contents/filters/filter_contents.cc
@@ -50,6 +50,8 @@ std::shared_ptr<FilterContents> FilterContents::MakeDirectionalGaussianBlur(
   return blur;
 }
 
+#define IMPELLER_ENABLE_NEW_GAUSSIAN_FILTER 1
+
 std::shared_ptr<FilterContents> FilterContents::MakeGaussianBlur(
     const FilterInput::Ref& input,
     Sigma sigma_x,
diff --git a/impeller/entity/contents/filters/gaussian_blur_filter_contents.cc b/impeller/entity/contents/filters/gaussian_blur_filter_contents.cc
index 5ac0ec0035142..66721ac1ee594 100644
--- a/impeller/entity/contents/filters/gaussian_blur_filter_contents.cc
+++ b/impeller/entity/contents/filters/gaussian_blur_filter_contents.cc
@@ -288,6 +288,7 @@ std::optional<Entity> GaussianBlurFilterContents::RenderFilter(
   }
 
   if (input_snapshot.value().texture->NeedsMipmapGeneration()) {
+    FML_LOG(ERROR) << "should generate mipmap";
     std::shared_ptr<CommandBuffer> mip_cmd_buffer =
         renderer.GetContext()->CreateCommandBuffer();
     std::shared_ptr<BlitPass> blit_pass = mip_cmd_buffer->CreateBlitPass();
diff --git a/impeller/entity/entity_pass.cc b/impeller/entity/entity_pass.cc
index aad8bd396a883..c74ee11a6ee0c 100644
--- a/impeller/entity/entity_pass.cc
+++ b/impeller/entity/entity_pass.cc
@@ -345,6 +345,13 @@ bool EntityPass::Render(ContentContext& renderer,
         renderer, root_render_target.GetRenderTargetSize(), /*mip_count=*/4,
         GetClearColorOrDefault(render_target.GetRenderTargetSize()));
 
+    offscreen_target.GetRenderTarget()
+        .GetRenderTargetTexture()
+        ->InvalidateMipmap();
+    FML_LOG(ERROR)
+        << "invalidating mips: "
+        << offscreen_target.GetRenderTarget().GetRenderTargetTexture();
+
     if (!OnRender(renderer,  // renderer
                   capture,   // capture
                   offscreen_target.GetRenderTarget()
diff --git a/impeller/renderer/backend/metal/texture_mtl.mm b/impeller/renderer/backend/metal/texture_mtl.mm
index d65937e8b9f09..e37defc847fb9 100644
--- a/impeller/renderer/backend/metal/texture_mtl.mm
+++ b/impeller/renderer/backend/metal/texture_mtl.mm
@@ -139,6 +139,8 @@ new TextureMTL(
     return false;
   }
 
+  FML_LOG(ERROR) << "mipmap generated";
+
   [encoder generateMipmapsForTexture:texture];
   mipmap_generated_ = true;
 
diff --git a/impeller/renderer/render_target.cc b/impeller/renderer/render_target.cc
index f2aca7f44d5d2..4d6500fcee036 100644
--- a/impeller/renderer/render_target.cc
+++ b/impeller/renderer/render_target.cc
@@ -314,6 +314,10 @@ RenderTarget RenderTarget::CreateOffscreenMSAA(
   color0_resolve_tex_desc.mip_count = mip_count;
 
   auto color0_resolve_tex = allocator.CreateTexture(color0_resolve_tex_desc);
+  if (mip_count > 1) {
+    FML_LOG(ERROR) << "created mip resolve texture: " << color0_resolve_tex
+                   << " " << mip_count;
+  }
   if (!color0_resolve_tex) {
     VALIDATION_LOG << "Could not create color texture.";
     return {};

From 8bf8bb9df00f9a2757d4df1c7e86be3a39813727 Mon Sep 17 00:00:00 2001
From: Aaron Clarke <aaclarke@google.com>
Date: Wed, 10 Jan 2024 11:06:21 -0800
Subject: [PATCH 07/28] Added texture_mipmap

---
 .../filters/gaussian_blur_filter_contents.cc  | 14 +++-----
 impeller/renderer/BUILD.gn                    |  2 ++
 impeller/renderer/texture_mipmap.cc           | 34 +++++++++++++++++++
 impeller/renderer/texture_mipmap.h            | 21 ++++++++++++
 4 files changed, 61 insertions(+), 10 deletions(-)
 create mode 100644 impeller/renderer/texture_mipmap.cc
 create mode 100644 impeller/renderer/texture_mipmap.h

diff --git a/impeller/entity/contents/filters/gaussian_blur_filter_contents.cc b/impeller/entity/contents/filters/gaussian_blur_filter_contents.cc
index 66721ac1ee594..674923520fd97 100644
--- a/impeller/entity/contents/filters/gaussian_blur_filter_contents.cc
+++ b/impeller/entity/contents/filters/gaussian_blur_filter_contents.cc
@@ -11,6 +11,7 @@
 #include "impeller/entity/texture_fill.vert.h"
 #include "impeller/renderer/command.h"
 #include "impeller/renderer/render_pass.h"
+#include "impeller/renderer/texture_mipmap.h"
 #include "impeller/renderer/vertex_buffer_builder.h"
 
 namespace impeller {
@@ -287,16 +288,9 @@ std::optional<Entity> GaussianBlurFilterContents::RenderFilter(
                                 entity.GetClipDepth());  // No blur to render.
   }
 
-  if (input_snapshot.value().texture->NeedsMipmapGeneration()) {
-    FML_LOG(ERROR) << "should generate mipmap";
-    std::shared_ptr<CommandBuffer> mip_cmd_buffer =
-        renderer.GetContext()->CreateCommandBuffer();
-    std::shared_ptr<BlitPass> blit_pass = mip_cmd_buffer->CreateBlitPass();
-    blit_pass->GenerateMipmap(input_snapshot.value().texture);
-    blit_pass->EncodeCommands(renderer.GetContext()->GetResourceAllocator());
-    bool success = mip_cmd_buffer->SubmitCommands(/*callback=*/nullptr);
-    FML_CHECK(success);
-  }
+  fml::Status mipmap_generation =
+      AddMipmapGeneration(renderer.GetContext(), input_snapshot->texture);
+  FML_CHECK(mipmap_generation.ok());
 
   Scalar desired_scalar =
       std::min(CalculateScale(scaled_sigma.x), CalculateScale(scaled_sigma.y));
diff --git a/impeller/renderer/BUILD.gn b/impeller/renderer/BUILD.gn
index 6b17817b849f3..3e0c7b5770420 100644
--- a/impeller/renderer/BUILD.gn
+++ b/impeller/renderer/BUILD.gn
@@ -92,6 +92,8 @@ impeller_component("renderer") {
     "snapshot.h",
     "surface.cc",
     "surface.h",
+    "texture_mipmap.cc",
+    "texture_mipmap.h",
     "vertex_buffer_builder.cc",
     "vertex_buffer_builder.h",
     "vertex_descriptor.cc",
diff --git a/impeller/renderer/texture_mipmap.cc b/impeller/renderer/texture_mipmap.cc
new file mode 100644
index 0000000000000..ac020644c293a
--- /dev/null
+++ b/impeller/renderer/texture_mipmap.cc
@@ -0,0 +1,34 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "impeller/renderer/texture_mipmap.h"
+#include "impeller/renderer/blit_pass.h"
+#include "impeller/renderer/command_buffer.h"
+
+
+namespace impeller {
+
+fml::Status AddMipmapGeneration(const std::shared_ptr<Context>& context,
+                                const std::shared_ptr<Texture>& texture) {
+  if (texture->NeedsMipmapGeneration()) {
+    std::shared_ptr<CommandBuffer> mip_cmd_buffer =
+        context->CreateCommandBuffer();
+    std::shared_ptr<BlitPass> blit_pass = mip_cmd_buffer->CreateBlitPass();
+    bool success = blit_pass->GenerateMipmap(texture);
+    if (!success) {
+      return fml::Status(fml::StatusCode::kUnknown, "");
+    }
+    success = blit_pass->EncodeCommands(context->GetResourceAllocator());
+    if (!success) {
+      return fml::Status(fml::StatusCode::kUnknown, "");
+    }
+    success = mip_cmd_buffer->SubmitCommands(/*callback=*/nullptr);
+    if (!success) {
+      return fml::Status(fml::StatusCode::kUnknown, "");
+    }
+  }
+  return {};
+}
+
+}  // namespace impeller
diff --git a/impeller/renderer/texture_mipmap.h b/impeller/renderer/texture_mipmap.h
new file mode 100644
index 0000000000000..f2f7d8cbb46d5
--- /dev/null
+++ b/impeller/renderer/texture_mipmap.h
@@ -0,0 +1,21 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef FLUTTER_IMPELLER_TEXTURE_MIPMAP_H_
+#define FLUTTER_IMPELLER_TEXTURE_MIPMAP_H_
+
+#include "flutter/fml/status.h"
+#include "impeller/core/texture.h"
+#include "impeller/renderer/context.h"
+
+namespace impeller {
+
+/// Adds a blit command to the render pass.
+[[nodiscard]] fml::Status AddMipmapGeneration(
+    const std::shared_ptr<Context>& context,
+    const std::shared_ptr<Texture>& texture);
+
+}  // namespace impeller
+
+#endif  // FLUTTER_IMPELLER_TEXTURE_MIPMAP_H_

From 97f5799425c6400dd35811e332a8cab0c916fe90 Mon Sep 17 00:00:00 2001
From: Aaron Clarke <aaclarke@google.com>
Date: Wed, 10 Jan 2024 12:55:22 -0800
Subject: [PATCH 08/28] moved mipmap generation to the spots identified by
 brandon

---
 .../filters/gaussian_blur_filter_contents.cc  |  8 +++++---
 impeller/entity/entity_pass.cc                | 20 +++++++++++++++----
 2 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/impeller/entity/contents/filters/gaussian_blur_filter_contents.cc b/impeller/entity/contents/filters/gaussian_blur_filter_contents.cc
index 674923520fd97..2f48013dd82b2 100644
--- a/impeller/entity/contents/filters/gaussian_blur_filter_contents.cc
+++ b/impeller/entity/contents/filters/gaussian_blur_filter_contents.cc
@@ -288,9 +288,11 @@ std::optional<Entity> GaussianBlurFilterContents::RenderFilter(
                                 entity.GetClipDepth());  // No blur to render.
   }
 
-  fml::Status mipmap_generation =
-      AddMipmapGeneration(renderer.GetContext(), input_snapshot->texture);
-  FML_CHECK(mipmap_generation.ok());
+  // In order to avoid shimmering in downsampling step, we should have mips.
+  if (input_snapshot->texture->GetMipCount() <= 1) {
+    FML_DLOG(ERROR) << "Applying gaussian blur without mipmap.";
+  }
+  FML_DCHECK(!input_snapshot->texture->NeedsMipmapGeneration());
 
   Scalar desired_scalar =
       std::min(CalculateScale(scaled_sigma.x), CalculateScale(scaled_sigma.y));
diff --git a/impeller/entity/entity_pass.cc b/impeller/entity/entity_pass.cc
index c74ee11a6ee0c..e2db028a71d34 100644
--- a/impeller/entity/entity_pass.cc
+++ b/impeller/entity/entity_pass.cc
@@ -25,6 +25,7 @@
 #include "impeller/geometry/color.h"
 #include "impeller/geometry/rect.h"
 #include "impeller/renderer/command_buffer.h"
+#include "impeller/renderer/texture_mipmap.h"
 
 #ifdef IMPELLER_DEBUG
 #include "impeller/entity/contents/checkerboard_contents.h"
@@ -341,16 +342,15 @@ bool EntityPass::Render(ContentContext& renderer,
   // and then blit the results onto the onscreen texture. If using this branch,
   // there's no need to set up a stencil attachment on the root render target.
   if (reads_from_onscreen_backdrop) {
-    auto offscreen_target = CreateRenderTarget(
+    EntityPassTarget offscreen_target = CreateRenderTarget(
         renderer, root_render_target.GetRenderTargetSize(), /*mip_count=*/4,
         GetClearColorOrDefault(render_target.GetRenderTargetSize()));
 
+    // If the render target texture is recycled, make sure the mipmaps are
+    // regenerated.
     offscreen_target.GetRenderTarget()
         .GetRenderTargetTexture()
         ->InvalidateMipmap();
-    FML_LOG(ERROR)
-        << "invalidating mips: "
-        << offscreen_target.GetRenderTarget().GetRenderTargetTexture();
 
     if (!OnRender(renderer,  // renderer
                   capture,   // capture
@@ -558,6 +558,12 @@ EntityPass::EntityResult EntityPass::GetEntityForElement(
       // rendering the backdrop, so if there's an active pass, end it prior to
       // rendering the subpass.
       pass_context.EndPass();
+
+      fml::Status mip_status =
+          AddMipmapGeneration(renderer.GetContext(), pass_context.GetTexture());
+      if (!mip_status.ok()) {
+        return EntityPass::EntityResult::Failure();
+      }
     }
 
     if (clip_coverage_stack.empty()) {
@@ -654,6 +660,12 @@ EntityPass::EntityResult EntityPass::GetEntityForElement(
     auto subpass_texture =
         subpass_target.GetRenderTarget().GetRenderTargetTexture();
 
+    fml::Status mip_status =
+        AddMipmapGeneration(renderer.GetContext(), subpass_texture);
+    if (!mip_status.ok()) {
+      return EntityPass::EntityResult::Failure();
+    }
+
     auto offscreen_texture_contents =
         subpass->delegate_->CreateContentsForSubpassTarget(
             subpass_texture,

From 80813fe21bbc7a63b3f3cae67422939968c24d1a Mon Sep 17 00:00:00 2001
From: Aaron Clarke <aaclarke@google.com>
Date: Wed, 10 Jan 2024 14:42:40 -0800
Subject: [PATCH 09/28] moved mipmap generation to the inline pass context

---
 impeller/entity/entity_pass.cc         | 13 -------------
 impeller/entity/inline_pass_context.cc | 11 +++++++++++
 2 files changed, 11 insertions(+), 13 deletions(-)

diff --git a/impeller/entity/entity_pass.cc b/impeller/entity/entity_pass.cc
index e2db028a71d34..4311566f027c1 100644
--- a/impeller/entity/entity_pass.cc
+++ b/impeller/entity/entity_pass.cc
@@ -25,7 +25,6 @@
 #include "impeller/geometry/color.h"
 #include "impeller/geometry/rect.h"
 #include "impeller/renderer/command_buffer.h"
-#include "impeller/renderer/texture_mipmap.h"
 
 #ifdef IMPELLER_DEBUG
 #include "impeller/entity/contents/checkerboard_contents.h"
@@ -558,12 +557,6 @@ EntityPass::EntityResult EntityPass::GetEntityForElement(
       // rendering the backdrop, so if there's an active pass, end it prior to
       // rendering the subpass.
       pass_context.EndPass();
-
-      fml::Status mip_status =
-          AddMipmapGeneration(renderer.GetContext(), pass_context.GetTexture());
-      if (!mip_status.ok()) {
-        return EntityPass::EntityResult::Failure();
-      }
     }
 
     if (clip_coverage_stack.empty()) {
@@ -660,12 +653,6 @@ EntityPass::EntityResult EntityPass::GetEntityForElement(
     auto subpass_texture =
         subpass_target.GetRenderTarget().GetRenderTargetTexture();
 
-    fml::Status mip_status =
-        AddMipmapGeneration(renderer.GetContext(), subpass_texture);
-    if (!mip_status.ok()) {
-      return EntityPass::EntityResult::Failure();
-    }
-
     auto offscreen_texture_contents =
         subpass->delegate_->CreateContentsForSubpassTarget(
             subpass_texture,
diff --git a/impeller/entity/inline_pass_context.cc b/impeller/entity/inline_pass_context.cc
index b8295c2cb444a..20ffc7190cd86 100644
--- a/impeller/entity/inline_pass_context.cc
+++ b/impeller/entity/inline_pass_context.cc
@@ -7,10 +7,12 @@
 #include <utility>
 
 #include "impeller/base/allocation.h"
+#include "flutter/fml/status.h"
 #include "impeller/base/validation.h"
 #include "impeller/core/formats.h"
 #include "impeller/entity/entity_pass_target.h"
 #include "impeller/renderer/command_buffer.h"
+#include "impeller/renderer/texture_mipmap.h"
 
 namespace impeller {
 
@@ -64,6 +66,15 @@ bool InlinePassContext::EndPass() {
     }
   }
 
+  std::shared_ptr<Texture> target_texture =
+      GetPassTarget().GetRenderTarget().GetRenderTargetTexture();
+  if (target_texture->NeedsMipmapGeneration()) {
+    fml::Status mip_status = AddMipmapGeneration(context_, target_texture);
+    if (!mip_status.ok()) {
+      return false;
+    }
+  }
+
   pass_ = nullptr;
   command_buffer_ = nullptr;
 

From 2b5790e28047c20de6998aef478891420ea5fc01 Mon Sep 17 00:00:00 2001
From: Aaron Clarke <aaclarke@google.com>
Date: Wed, 10 Jan 2024 14:44:02 -0800
Subject: [PATCH 10/28] format

---
 impeller/renderer/texture_mipmap.cc | 1 -
 1 file changed, 1 deletion(-)

diff --git a/impeller/renderer/texture_mipmap.cc b/impeller/renderer/texture_mipmap.cc
index ac020644c293a..823b80d662b25 100644
--- a/impeller/renderer/texture_mipmap.cc
+++ b/impeller/renderer/texture_mipmap.cc
@@ -6,7 +6,6 @@
 #include "impeller/renderer/blit_pass.h"
 #include "impeller/renderer/command_buffer.h"
 
-
 namespace impeller {
 
 fml::Status AddMipmapGeneration(const std::shared_ptr<Context>& context,

From 7204e7cebc78b51f67ee20762cbb296cca7b62c8 Mon Sep 17 00:00:00 2001
From: Aaron Clarke <aaclarke@google.com>
Date: Wed, 10 Jan 2024 14:51:42 -0800
Subject: [PATCH 11/28] removed logs

---
 impeller/renderer/backend/metal/texture_mtl.mm | 2 --
 impeller/renderer/render_target.cc             | 4 ----
 2 files changed, 6 deletions(-)

diff --git a/impeller/renderer/backend/metal/texture_mtl.mm b/impeller/renderer/backend/metal/texture_mtl.mm
index e37defc847fb9..d65937e8b9f09 100644
--- a/impeller/renderer/backend/metal/texture_mtl.mm
+++ b/impeller/renderer/backend/metal/texture_mtl.mm
@@ -139,8 +139,6 @@ new TextureMTL(
     return false;
   }
 
-  FML_LOG(ERROR) << "mipmap generated";
-
   [encoder generateMipmapsForTexture:texture];
   mipmap_generated_ = true;
 
diff --git a/impeller/renderer/render_target.cc b/impeller/renderer/render_target.cc
index 4d6500fcee036..f2aca7f44d5d2 100644
--- a/impeller/renderer/render_target.cc
+++ b/impeller/renderer/render_target.cc
@@ -314,10 +314,6 @@ RenderTarget RenderTarget::CreateOffscreenMSAA(
   color0_resolve_tex_desc.mip_count = mip_count;
 
   auto color0_resolve_tex = allocator.CreateTexture(color0_resolve_tex_desc);
-  if (mip_count > 1) {
-    FML_LOG(ERROR) << "created mip resolve texture: " << color0_resolve_tex
-                   << " " << mip_count;
-  }
   if (!color0_resolve_tex) {
     VALIDATION_LOG << "Could not create color texture.";
     return {};

From afdc277229c337f700b594e8f0b79804416759c2 Mon Sep 17 00:00:00 2001
From: Aaron Clarke <aaclarke@google.com>
Date: Thu, 11 Jan 2024 09:21:45 -0800
Subject: [PATCH 12/28] Removed invalidation and updated the docstring on
 NeedsMipmapGeneration

---
 impeller/core/texture.cc       | 4 ----
 impeller/core/texture.h        | 5 +++--
 impeller/entity/entity_pass.cc | 6 ------
 3 files changed, 3 insertions(+), 12 deletions(-)

diff --git a/impeller/core/texture.cc b/impeller/core/texture.cc
index f8ba083783700..bb2f125aea503 100644
--- a/impeller/core/texture.cc
+++ b/impeller/core/texture.cc
@@ -86,8 +86,4 @@ bool Texture::NeedsMipmapGeneration() const {
   return !mipmap_generated_ && desc_.mip_count > 1;
 }
 
-void Texture::InvalidateMipmap() {
-  mipmap_generated_ = false;
-}
-
 }  // namespace impeller
diff --git a/impeller/core/texture.h b/impeller/core/texture.h
index d0bcc40432062..af14a9e9331c9 100644
--- a/impeller/core/texture.h
+++ b/impeller/core/texture.h
@@ -45,10 +45,11 @@ class Texture {
 
   virtual Scalar GetYCoordScale() const;
 
+  /// Returns true if mipmaps have never been generated.
+  /// The contents of the mipmap may be out of date if the root texture has been
+  /// modified and the mipmaps hasn't been regenerated.
   bool NeedsMipmapGeneration() const;
 
-  void InvalidateMipmap();
-
  protected:
   explicit Texture(TextureDescriptor desc);
 
diff --git a/impeller/entity/entity_pass.cc b/impeller/entity/entity_pass.cc
index 4311566f027c1..789c5615a5fab 100644
--- a/impeller/entity/entity_pass.cc
+++ b/impeller/entity/entity_pass.cc
@@ -345,12 +345,6 @@ bool EntityPass::Render(ContentContext& renderer,
         renderer, root_render_target.GetRenderTargetSize(), /*mip_count=*/4,
         GetClearColorOrDefault(render_target.GetRenderTargetSize()));
 
-    // If the render target texture is recycled, make sure the mipmaps are
-    // regenerated.
-    offscreen_target.GetRenderTarget()
-        .GetRenderTargetTexture()
-        ->InvalidateMipmap();
-
     if (!OnRender(renderer,  // renderer
                   capture,   // capture
                   offscreen_target.GetRenderTarget()

From 6aa39c3b9a2a73d8861f866de208a2eaa126e7a4 Mon Sep 17 00:00:00 2001
From: Aaron Clarke <aaclarke@google.com>
Date: Thu, 11 Jan 2024 10:20:30 -0800
Subject: [PATCH 13/28] brought over the mip_count parameter to non msaa paths

---
 impeller/aiks/picture.cc                                  | 7 ++++---
 impeller/entity/contents/content_context.cc               | 2 +-
 .../entity/contents/tiled_texture_contents_unittests.cc   | 3 ++-
 impeller/entity/entity_pass.cc                            | 3 ++-
 impeller/entity/entity_unittests.cc                       | 5 +++--
 impeller/entity/inline_pass_context.cc                    | 2 +-
 impeller/renderer/render_target.cc                        | 2 ++
 impeller/renderer/render_target.h                         | 1 +
 impeller/renderer/renderer_unittests.cc                   | 8 ++++----
 9 files changed, 20 insertions(+), 13 deletions(-)

diff --git a/impeller/aiks/picture.cc b/impeller/aiks/picture.cc
index bd32f9068f895..8fc31dc31f45b 100644
--- a/impeller/aiks/picture.cc
+++ b/impeller/aiks/picture.cc
@@ -72,9 +72,10 @@ std::shared_ptr<Texture> Picture::RenderToTexture(
     );
   } else {
     target = RenderTarget::CreateOffscreen(
-        *impeller_context,                            // context
-        render_target_allocator,                      // allocator
-        size,                                         // size
+        *impeller_context,        // context
+        render_target_allocator,  // allocator
+        size,                     // size
+        /*mip_count=*/1,
         "Picture Snapshot",                           // label
         RenderTarget::kDefaultColorAttachmentConfig,  // color_attachment_config
         std::nullopt  // stencil_attachment_config
diff --git a/impeller/entity/contents/content_context.cc b/impeller/entity/contents/content_context.cc
index 6cd649eaa582d..7680481181b25 100644
--- a/impeller/entity/contents/content_context.cc
+++ b/impeller/entity/contents/content_context.cc
@@ -425,7 +425,7 @@ fml::StatusOr<RenderTarget> ContentContext::MakeSubpass(
     );
   } else {
     subpass_target = RenderTarget::CreateOffscreen(
-        *context, *GetRenderTargetCache(), texture_size,
+        *context, *GetRenderTargetCache(), texture_size, /*mip_count=*/1,
         SPrintF("%s Offscreen", label.c_str()),
         RenderTarget::kDefaultColorAttachmentConfig,  //
         std::nullopt  // stencil_attachment_config
diff --git a/impeller/entity/contents/tiled_texture_contents_unittests.cc b/impeller/entity/contents/tiled_texture_contents_unittests.cc
index 8fc5fecd99fb7..4715eaad79133 100644
--- a/impeller/entity/contents/tiled_texture_contents_unittests.cc
+++ b/impeller/entity/contents/tiled_texture_contents_unittests.cc
@@ -69,7 +69,8 @@ TEST_P(EntityTest, TiledTextureContentsRendersWithCorrectPipelineExternalOES) {
   auto buffer = content_context->GetContext()->CreateCommandBuffer();
   auto render_target = RenderTarget::CreateOffscreenMSAA(
       *content_context->GetContext(),
-      *GetContentContext()->GetRenderTargetCache(), {100, 100});
+      *GetContentContext()->GetRenderTargetCache(), {100, 100},
+      /*mip_count=*/1);
   auto render_pass = buffer->CreateRenderPass(render_target);
 
   ASSERT_TRUE(contents.Render(*GetContentContext(), {}, *render_pass));
diff --git a/impeller/entity/entity_pass.cc b/impeller/entity/entity_pass.cc
index 789c5615a5fab..5d98e94cf7d63 100644
--- a/impeller/entity/entity_pass.cc
+++ b/impeller/entity/entity_pass.cc
@@ -278,7 +278,8 @@ static EntityPassTarget CreateRenderTarget(ContentContext& renderer,
         *context,                          // context
         *renderer.GetRenderTargetCache(),  // allocator
         size,                              // size
-        "EntityPass",                      // label
+        /*mip_count=*/mip_count,
+        "EntityPass",  // label
         RenderTarget::AttachmentConfig{
             .storage_mode = StorageMode::kDevicePrivate,
             .load_action = LoadAction::kDontCare,
diff --git a/impeller/entity/entity_unittests.cc b/impeller/entity/entity_unittests.cc
index 520d2ee9ee3db..a24e8e2b59931 100644
--- a/impeller/entity/entity_unittests.cc
+++ b/impeller/entity/entity_unittests.cc
@@ -2511,8 +2511,9 @@ TEST_P(EntityTest, AdvancedBlendCoverageHintIsNotResetByEntityPass) {
       .store_action = StoreAction::kDontCare,
       .clear_color = Color::BlackTransparent()};
   auto rt = RenderTarget::CreateOffscreen(
-      *GetContext(), *test_allocator, ISize::MakeWH(1000, 1000), "Offscreen",
-      RenderTarget::kDefaultColorAttachmentConfig, stencil_config);
+      *GetContext(), *test_allocator, ISize::MakeWH(1000, 1000),
+      /*mip_count=*/1, "Offscreen", RenderTarget::kDefaultColorAttachmentConfig,
+      stencil_config);
   auto content_context = ContentContext(
       GetContext(), TypographerContextSkia::Make(), test_allocator);
   pass->AddEntity(std::move(entity));
diff --git a/impeller/entity/inline_pass_context.cc b/impeller/entity/inline_pass_context.cc
index 20ffc7190cd86..73aeff1735c7a 100644
--- a/impeller/entity/inline_pass_context.cc
+++ b/impeller/entity/inline_pass_context.cc
@@ -6,8 +6,8 @@
 
 #include <utility>
 
-#include "impeller/base/allocation.h"
 #include "flutter/fml/status.h"
+#include "impeller/base/allocation.h"
 #include "impeller/base/validation.h"
 #include "impeller/core/formats.h"
 #include "impeller/entity/entity_pass_target.h"
diff --git a/impeller/renderer/render_target.cc b/impeller/renderer/render_target.cc
index f2aca7f44d5d2..d4a1e3c6cf0bb 100644
--- a/impeller/renderer/render_target.cc
+++ b/impeller/renderer/render_target.cc
@@ -224,6 +224,7 @@ RenderTarget RenderTarget::CreateOffscreen(
     const Context& context,
     RenderTargetAllocator& allocator,
     ISize size,
+    int mip_count,
     const std::string& label,
     AttachmentConfig color_attachment_config,
     std::optional<AttachmentConfig> stencil_attachment_config) {
@@ -237,6 +238,7 @@ RenderTarget RenderTarget::CreateOffscreen(
   color_tex0.storage_mode = color_attachment_config.storage_mode;
   color_tex0.format = pixel_format;
   color_tex0.size = size;
+  color_tex0.mip_count = mip_count;
   color_tex0.usage = static_cast<uint64_t>(TextureUsage::kRenderTarget) |
                      static_cast<uint64_t>(TextureUsage::kShaderRead);
 
diff --git a/impeller/renderer/render_target.h b/impeller/renderer/render_target.h
index 388cfb7029fa8..997ebac1b7eab 100644
--- a/impeller/renderer/render_target.h
+++ b/impeller/renderer/render_target.h
@@ -86,6 +86,7 @@ class RenderTarget final {
       const Context& context,
       RenderTargetAllocator& allocator,
       ISize size,
+      int mip_count,
       const std::string& label = "Offscreen",
       AttachmentConfig color_attachment_config = kDefaultColorAttachmentConfig,
       std::optional<AttachmentConfig> stencil_attachment_config =
diff --git a/impeller/renderer/renderer_unittests.cc b/impeller/renderer/renderer_unittests.cc
index dcc40359f9d27..f34b2440b6b6b 100644
--- a/impeller/renderer/renderer_unittests.cc
+++ b/impeller/renderer/renderer_unittests.cc
@@ -1286,8 +1286,8 @@ TEST_P(RendererTest, CanPreAllocateCommands) {
   auto render_target_cache = std::make_shared<RenderTargetAllocator>(
       GetContext()->GetResourceAllocator());
 
-  auto render_target =
-      RenderTarget::CreateOffscreen(*context, *render_target_cache, {100, 100});
+  auto render_target = RenderTarget::CreateOffscreen(
+      *context, *render_target_cache, {100, 100}, /*mip_count=*/1);
   auto render_pass = cmd_buffer->CreateRenderPass(render_target);
 
   render_pass->ReserveCommands(100u);
@@ -1301,8 +1301,8 @@ TEST_P(RendererTest, CanLookupRenderTargetProperties) {
   auto render_target_cache = std::make_shared<RenderTargetAllocator>(
       GetContext()->GetResourceAllocator());
 
-  auto render_target =
-      RenderTarget::CreateOffscreen(*context, *render_target_cache, {100, 100});
+  auto render_target = RenderTarget::CreateOffscreen(
+      *context, *render_target_cache, {100, 100}, /*mip_count=*/1);
   auto render_pass = cmd_buffer->CreateRenderPass(render_target);
 
   EXPECT_EQ(render_pass->GetSampleCount(), render_target.GetSampleCount());

From 6896e32886c0cf466922832ff643321566a40d8d Mon Sep 17 00:00:00 2001
From: Aaron Clarke <aaclarke@google.com>
Date: Thu, 11 Jan 2024 10:25:00 -0800
Subject: [PATCH 14/28] added todo

---
 impeller/entity/shaders/gaussian_blur/kernel.glsl | 1 +
 1 file changed, 1 insertion(+)

diff --git a/impeller/entity/shaders/gaussian_blur/kernel.glsl b/impeller/entity/shaders/gaussian_blur/kernel.glsl
index 7a6ff6f376d56..7667b6a34da56 100644
--- a/impeller/entity/shaders/gaussian_blur/kernel.glsl
+++ b/impeller/entity/shaders/gaussian_blur/kernel.glsl
@@ -23,6 +23,7 @@ blur_info;
 
 f16vec4 Sample(f16sampler2D tex, vec2 coords, float lod) {
 #if ENABLE_DECAL_SPECIALIZATION
+  // TODO(gaaclarke): Make a LOD variant here.
   return IPHalfSampleDecal(tex, coords);
 #else
   return textureLod(tex, coords, lod);

From e59dc8c6e4ac480f889dcedc977f2b7b3eb4a247 Mon Sep 17 00:00:00 2001
From: Aaron Clarke <aaclarke@google.com>
Date: Thu, 11 Jan 2024 11:48:46 -0800
Subject: [PATCH 15/28] license

---
 ci/licenses_golden/licenses_flutter | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/ci/licenses_golden/licenses_flutter b/ci/licenses_golden/licenses_flutter
index 8b069e99fc686..8addf725c1d76 100644
--- a/ci/licenses_golden/licenses_flutter
+++ b/ci/licenses_golden/licenses_flutter
@@ -5553,6 +5553,8 @@ ORIGIN: ../../../flutter/impeller/renderer/snapshot.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/impeller/renderer/stroke.comp + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/impeller/renderer/surface.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/impeller/renderer/surface.h + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/impeller/renderer/texture_mipmap.cc + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/impeller/renderer/texture_mipmap.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/impeller/renderer/threadgroup_sizing_test.comp + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/impeller/renderer/vertex_buffer_builder.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/impeller/renderer/vertex_buffer_builder.h + ../../../flutter/LICENSE
@@ -8381,6 +8383,8 @@ FILE: ../../../flutter/impeller/renderer/snapshot.h
 FILE: ../../../flutter/impeller/renderer/stroke.comp
 FILE: ../../../flutter/impeller/renderer/surface.cc
 FILE: ../../../flutter/impeller/renderer/surface.h
+FILE: ../../../flutter/impeller/renderer/texture_mipmap.cc
+FILE: ../../../flutter/impeller/renderer/texture_mipmap.h
 FILE: ../../../flutter/impeller/renderer/threadgroup_sizing_test.comp
 FILE: ../../../flutter/impeller/renderer/vertex_buffer_builder.cc
 FILE: ../../../flutter/impeller/renderer/vertex_buffer_builder.h

From 3f52295d3fee601227e16aedad137659b6f86a9c Mon Sep 17 00:00:00 2001
From: Aaron Clarke <aaclarke@google.com>
Date: Thu, 11 Jan 2024 11:56:43 -0800
Subject: [PATCH 16/28] added decal lod support

---
 impeller/compiler/shader_lib/impeller/texture.glsl | 9 +++++++++
 impeller/entity/shaders/gaussian_blur/kernel.glsl  | 3 +--
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/impeller/compiler/shader_lib/impeller/texture.glsl b/impeller/compiler/shader_lib/impeller/texture.glsl
index 56be817085db3..d8673ab52e6b7 100644
--- a/impeller/compiler/shader_lib/impeller/texture.glsl
+++ b/impeller/compiler/shader_lib/impeller/texture.glsl
@@ -140,6 +140,15 @@ f16vec4 IPHalfSampleDecal(f16sampler2D texture_sampler, vec2 coords) {
   return texture(texture_sampler, coords, kDefaultMipBiasHalf);
 }
 
+/// Sample a texture with decal tile mode at specified LOD.
+f16vec4 IPHalfSampleDecalLod(f16sampler2D texture_sampler, vec2 coords, float lod) {
+  if (any(lessThan(coords, vec2(0))) ||
+      any(greaterThanEqual(coords, vec2(1)))) {
+    return f16vec4(0.0);
+  }
+  return textureLod(texture_sampler, coords, lod);
+}
+
 /// Sample a texture, emulating a specific tile mode.
 ///
 /// This is useful for Impeller graphics backend that don't have native support
diff --git a/impeller/entity/shaders/gaussian_blur/kernel.glsl b/impeller/entity/shaders/gaussian_blur/kernel.glsl
index 7667b6a34da56..a45b874b581c1 100644
--- a/impeller/entity/shaders/gaussian_blur/kernel.glsl
+++ b/impeller/entity/shaders/gaussian_blur/kernel.glsl
@@ -23,8 +23,7 @@ blur_info;
 
 f16vec4 Sample(f16sampler2D tex, vec2 coords, float lod) {
 #if ENABLE_DECAL_SPECIALIZATION
-  // TODO(gaaclarke): Make a LOD variant here.
-  return IPHalfSampleDecal(tex, coords);
+  return IPHalfSampleDecalLod(tex, coords, lod);
 #else
   return textureLod(tex, coords, lod);
 #endif

From a61094b5e0b9abf6d5f433a5064d38a632f8a680 Mon Sep 17 00:00:00 2001
From: Aaron Clarke <aaclarke@google.com>
Date: Thu, 11 Jan 2024 16:08:15 -0800
Subject: [PATCH 17/28] removed check for needsmipmapgeneration

---
 impeller/entity/inline_pass_context.cc |  2 +-
 impeller/renderer/texture_mipmap.cc    | 30 ++++++++++++--------------
 2 files changed, 15 insertions(+), 17 deletions(-)

diff --git a/impeller/entity/inline_pass_context.cc b/impeller/entity/inline_pass_context.cc
index 73aeff1735c7a..1a4589c24d32f 100644
--- a/impeller/entity/inline_pass_context.cc
+++ b/impeller/entity/inline_pass_context.cc
@@ -68,7 +68,7 @@ bool InlinePassContext::EndPass() {
 
   std::shared_ptr<Texture> target_texture =
       GetPassTarget().GetRenderTarget().GetRenderTargetTexture();
-  if (target_texture->NeedsMipmapGeneration()) {
+  if (target_texture->GetMipCount() > 1) {
     fml::Status mip_status = AddMipmapGeneration(context_, target_texture);
     if (!mip_status.ok()) {
       return false;
diff --git a/impeller/renderer/texture_mipmap.cc b/impeller/renderer/texture_mipmap.cc
index 823b80d662b25..0a633c645958a 100644
--- a/impeller/renderer/texture_mipmap.cc
+++ b/impeller/renderer/texture_mipmap.cc
@@ -10,22 +10,20 @@ namespace impeller {
 
 fml::Status AddMipmapGeneration(const std::shared_ptr<Context>& context,
                                 const std::shared_ptr<Texture>& texture) {
-  if (texture->NeedsMipmapGeneration()) {
-    std::shared_ptr<CommandBuffer> mip_cmd_buffer =
-        context->CreateCommandBuffer();
-    std::shared_ptr<BlitPass> blit_pass = mip_cmd_buffer->CreateBlitPass();
-    bool success = blit_pass->GenerateMipmap(texture);
-    if (!success) {
-      return fml::Status(fml::StatusCode::kUnknown, "");
-    }
-    success = blit_pass->EncodeCommands(context->GetResourceAllocator());
-    if (!success) {
-      return fml::Status(fml::StatusCode::kUnknown, "");
-    }
-    success = mip_cmd_buffer->SubmitCommands(/*callback=*/nullptr);
-    if (!success) {
-      return fml::Status(fml::StatusCode::kUnknown, "");
-    }
+  std::shared_ptr<CommandBuffer> mip_cmd_buffer =
+      context->CreateCommandBuffer();
+  std::shared_ptr<BlitPass> blit_pass = mip_cmd_buffer->CreateBlitPass();
+  bool success = blit_pass->GenerateMipmap(texture);
+  if (!success) {
+    return fml::Status(fml::StatusCode::kUnknown, "");
+  }
+  success = blit_pass->EncodeCommands(context->GetResourceAllocator());
+  if (!success) {
+    return fml::Status(fml::StatusCode::kUnknown, "");
+  }
+  success = mip_cmd_buffer->SubmitCommands(/*callback=*/nullptr);
+  if (!success) {
+    return fml::Status(fml::StatusCode::kUnknown, "");
   }
   return {};
 }

From 1930bfd62901938c59a929964b8936992e5f8851 Mon Sep 17 00:00:00 2001
From: Aaron Clarke <aaclarke@google.com>
Date: Thu, 11 Jan 2024 16:30:05 -0800
Subject: [PATCH 18/28] Revert "added decal lod support"

This reverts commit 423b717e0fde6e3dc3551eb8f8f17c8c1a60c222.
---
 impeller/compiler/shader_lib/impeller/texture.glsl | 9 ---------
 impeller/entity/shaders/gaussian_blur/kernel.glsl  | 3 ++-
 2 files changed, 2 insertions(+), 10 deletions(-)

diff --git a/impeller/compiler/shader_lib/impeller/texture.glsl b/impeller/compiler/shader_lib/impeller/texture.glsl
index d8673ab52e6b7..56be817085db3 100644
--- a/impeller/compiler/shader_lib/impeller/texture.glsl
+++ b/impeller/compiler/shader_lib/impeller/texture.glsl
@@ -140,15 +140,6 @@ f16vec4 IPHalfSampleDecal(f16sampler2D texture_sampler, vec2 coords) {
   return texture(texture_sampler, coords, kDefaultMipBiasHalf);
 }
 
-/// Sample a texture with decal tile mode at specified LOD.
-f16vec4 IPHalfSampleDecalLod(f16sampler2D texture_sampler, vec2 coords, float lod) {
-  if (any(lessThan(coords, vec2(0))) ||
-      any(greaterThanEqual(coords, vec2(1)))) {
-    return f16vec4(0.0);
-  }
-  return textureLod(texture_sampler, coords, lod);
-}
-
 /// Sample a texture, emulating a specific tile mode.
 ///
 /// This is useful for Impeller graphics backend that don't have native support
diff --git a/impeller/entity/shaders/gaussian_blur/kernel.glsl b/impeller/entity/shaders/gaussian_blur/kernel.glsl
index a45b874b581c1..7667b6a34da56 100644
--- a/impeller/entity/shaders/gaussian_blur/kernel.glsl
+++ b/impeller/entity/shaders/gaussian_blur/kernel.glsl
@@ -23,7 +23,8 @@ blur_info;
 
 f16vec4 Sample(f16sampler2D tex, vec2 coords, float lod) {
 #if ENABLE_DECAL_SPECIALIZATION
-  return IPHalfSampleDecalLod(tex, coords, lod);
+  // TODO(gaaclarke): Make a LOD variant here.
+  return IPHalfSampleDecal(tex, coords);
 #else
   return textureLod(tex, coords, lod);
 #endif

From c42daef3476053dd3027a063882264d065368f01 Mon Sep 17 00:00:00 2001
From: Aaron Clarke <aaclarke@google.com>
Date: Thu, 11 Jan 2024 16:33:56 -0800
Subject: [PATCH 19/28] removed explicit lod

---
 .../contents/filters/gaussian_blur_filter_contents.cc     | 8 --------
 .../contents/filters/gaussian_blur_filter_contents.h      | 1 -
 .../filters/gaussian_blur_filter_contents_unittests.cc    | 5 +----
 impeller/entity/shaders/gaussian_blur/kernel.glsl         | 8 +++-----
 4 files changed, 4 insertions(+), 18 deletions(-)

diff --git a/impeller/entity/contents/filters/gaussian_blur_filter_contents.cc b/impeller/entity/contents/filters/gaussian_blur_filter_contents.cc
index 2f48013dd82b2..11d192c0357e3 100644
--- a/impeller/entity/contents/filters/gaussian_blur_filter_contents.cc
+++ b/impeller/entity/contents/filters/gaussian_blur_filter_contents.cc
@@ -193,10 +193,6 @@ Rect MakeReferenceUVs(const Rect& reference, const Rect& rect) {
                                      rect.GetSize());
   return result.Scale(1.0f / Vector2(reference.GetSize()));
 }
-
-Scalar CalculateLOD(Scalar scalar) {
-  return fabsf(log2f(1.f / scalar));
-}
 }  // namespace
 
 GaussianBlurFilterContents::GaussianBlurFilterContents(
@@ -296,7 +292,6 @@ std::optional<Entity> GaussianBlurFilterContents::RenderFilter(
 
   Scalar desired_scalar =
       std::min(CalculateScale(scaled_sigma.x), CalculateScale(scaled_sigma.y));
-  Scalar lod = CalculateLOD(desired_scalar);
   // TODO(jonahwilliams): If desired_scalar is 1.0 and we fully acquired the
   // gutter from the expanded_coverage_hint, we can skip the downsample pass.
   // pass.
@@ -364,7 +359,6 @@ std::optional<Entity> GaussianBlurFilterContents::RenderFilter(
           .blur_radius =
               static_cast<int>(std::round(blur_radius.y * effective_scalar.y)),
           .step_size = 1,
-          .lod = lod,
       },
       /*destination_target=*/std::nullopt, blur_uvs);
 
@@ -387,7 +381,6 @@ std::optional<Entity> GaussianBlurFilterContents::RenderFilter(
           .blur_radius =
               static_cast<int>(std::round(blur_radius.x * effective_scalar.x)),
           .step_size = 1,
-          .lod = lod,
       },
       pass3_destination, blur_uvs);
 
@@ -448,7 +441,6 @@ Scalar GaussianBlurFilterContents::ScaleSigma(Scalar sigma) {
 KernelPipeline::FragmentShader::KernelSamples GenerateBlurInfo(
     BlurParameters parameters) {
   KernelPipeline::FragmentShader::KernelSamples result;
-  result.lod = parameters.lod;
   result.sample_count =
       ((2 * parameters.blur_radius) / parameters.step_size) + 1;
   // 32 comes from kernel.glsl.
diff --git a/impeller/entity/contents/filters/gaussian_blur_filter_contents.h b/impeller/entity/contents/filters/gaussian_blur_filter_contents.h
index fdcd9ba3a6143..1bb594f3e4ae6 100644
--- a/impeller/entity/contents/filters/gaussian_blur_filter_contents.h
+++ b/impeller/entity/contents/filters/gaussian_blur_filter_contents.h
@@ -16,7 +16,6 @@ struct BlurParameters {
   Scalar blur_sigma;
   int blur_radius;
   int step_size;
-  Scalar lod;
 };
 
 KernelPipeline::FragmentShader::KernelSamples GenerateBlurInfo(
diff --git a/impeller/entity/contents/filters/gaussian_blur_filter_contents_unittests.cc b/impeller/entity/contents/filters/gaussian_blur_filter_contents_unittests.cc
index c2dddf4052c07..ba3053483181f 100644
--- a/impeller/entity/contents/filters/gaussian_blur_filter_contents_unittests.cc
+++ b/impeller/entity/contents/filters/gaussian_blur_filter_contents_unittests.cc
@@ -462,8 +462,7 @@ TEST(GaussianBlurFilterContentsTest, Coefficients) {
   BlurParameters parameters = {.blur_uv_offset = Point(1, 0),
                                .blur_sigma = 1,
                                .blur_radius = 5,
-                               .step_size = 1,
-                               .lod = -1.f};
+                               .step_size = 1};
   KernelPipeline::FragmentShader::KernelSamples samples =
       GenerateBlurInfo(parameters);
   EXPECT_EQ(samples.sample_count, 9);
@@ -482,8 +481,6 @@ TEST(GaussianBlurFilterContentsTest, Coefficients) {
     EXPECT_TRUE(samples.samples[i + 1].coefficient >
                 samples.samples[i].coefficient);
   }
-
-  EXPECT_FLOAT_EQ(samples.lod, -1.f);
 }
 
 }  // namespace testing
diff --git a/impeller/entity/shaders/gaussian_blur/kernel.glsl b/impeller/entity/shaders/gaussian_blur/kernel.glsl
index 7667b6a34da56..c491acbbb0fc4 100644
--- a/impeller/entity/shaders/gaussian_blur/kernel.glsl
+++ b/impeller/entity/shaders/gaussian_blur/kernel.glsl
@@ -17,16 +17,15 @@ struct KernelSample {
 uniform KernelSamples {
   int sample_count;
   KernelSample samples[32];
-  float lod;
 }
 blur_info;
 
-f16vec4 Sample(f16sampler2D tex, vec2 coords, float lod) {
+f16vec4 Sample(f16sampler2D tex, vec2 coords) {
 #if ENABLE_DECAL_SPECIALIZATION
   // TODO(gaaclarke): Make a LOD variant here.
   return IPHalfSampleDecal(tex, coords);
 #else
-  return textureLod(tex, coords, lod);
+  return texture(tex, coords);
 #endif
 }
 
@@ -41,8 +40,7 @@ void main() {
     float16_t coefficient = float16_t(blur_info.samples[i].coefficient);
     total_color +=
         coefficient * Sample(texture_sampler,
-                             v_texture_coords + blur_info.samples[i].uv_offset,
-                             blur_info.lod);
+                             v_texture_coords + blur_info.samples[i].uv_offset);
   }
 
   frag_color = total_color;

From eb8496463c201e8ffef6d6099cf7b6636b4c1129 Mon Sep 17 00:00:00 2001
From: Aaron Clarke <aaclarke@google.com>
Date: Thu, 11 Jan 2024 17:32:11 -0800
Subject: [PATCH 20/28] only started incrementing the mip_count if we are using
 blur

---
 impeller/aiks/canvas.cc             | 32 ++++++++++++++++++++
 impeller/entity/entity_pass.cc      | 45 ++++++++++++++++++++++++-----
 impeller/entity/entity_pass.h       | 10 +++++++
 impeller/entity/entity_unittests.cc |  1 +
 4 files changed, 80 insertions(+), 8 deletions(-)

diff --git a/impeller/aiks/canvas.cc b/impeller/aiks/canvas.cc
index c5b9ae9e598b7..49c6851bd3284 100644
--- a/impeller/aiks/canvas.cc
+++ b/impeller/aiks/canvas.cc
@@ -133,6 +133,35 @@ void Canvas::Save() {
   Save(false);
 }
 
+namespace {
+class MipCountVisitor : public ImageFilterVisitor {
+ public:
+  virtual void Visit(const BlurImageFilter& filter) { required_mip_count_ = 4; }
+  virtual void Visit(const LocalMatrixImageFilter& filter) {
+    required_mip_count_ = 1;
+  }
+  virtual void Visit(const DilateImageFilter& filter) {
+    required_mip_count_ = 1;
+  }
+  virtual void Visit(const ErodeImageFilter& filter) {
+    required_mip_count_ = 1;
+  }
+  virtual void Visit(const MatrixImageFilter& filter) {
+    required_mip_count_ = 1;
+  }
+  virtual void Visit(const ComposeImageFilter& filter) {
+    required_mip_count_ = 1;
+  }
+  virtual void Visit(const ColorImageFilter& filter) {
+    required_mip_count_ = 1;
+  }
+  int32_t GetRequiredMipCount() const { return required_mip_count_; }
+
+ private:
+  int32_t required_mip_count_ = -1;
+};
+}  // namespace
+
 void Canvas::Save(bool create_subpass,
                   BlendMode blend_mode,
                   const std::shared_ptr<ImageFilter>& backdrop_filter) {
@@ -156,6 +185,9 @@ void Canvas::Save(bool create_subpass,
             return filter;
           };
       subpass->SetBackdropFilter(backdrop_filter_proc);
+      MipCountVisitor mip_count_visitor;
+      backdrop_filter->Visit(mip_count_visitor);
+      subpass->SetRequiredMipCount(mip_count_visitor.GetRequiredMipCount());
     }
     subpass->SetBlendMode(blend_mode);
     current_pass_ = GetCurrentPass().AddSubpass(std::move(subpass));
diff --git a/impeller/entity/entity_pass.cc b/impeller/entity/entity_pass.cc
index 5d98e94cf7d63..576c3a97a6ff9 100644
--- a/impeller/entity/entity_pass.cc
+++ b/impeller/entity/entity_pass.cc
@@ -325,13 +325,23 @@ bool EntityPass::Render(ContentContext& renderer,
                   Rect::MakeSize(root_render_target.GetRenderTargetSize()),
                   {.readonly = true});
 
-  IterateAllEntities([lazy_glyph_atlas =
-                          renderer.GetLazyGlyphAtlas()](const Entity& entity) {
-    if (const auto& contents = entity.GetContents()) {
-      contents->PopulateGlyphAtlas(lazy_glyph_atlas, entity.DeriveTextScale());
-    }
-    return true;
-  });
+  int32_t required_mip_count = 1;
+  IterateAllElements(
+      [&required_mip_count, lazy_glyph_atlas = renderer.GetLazyGlyphAtlas()](
+          const Element& element) {
+        if (auto entity = std::get_if<Entity>(&element)) {
+          if (const auto& contents = entity->GetContents()) {
+            contents->PopulateGlyphAtlas(lazy_glyph_atlas,
+                                         entity->DeriveTextScale());
+          }
+        }
+        if (auto subpass = std::get_if<std::unique_ptr<EntityPass>>(&element)) {
+          const EntityPass* entity_pass = subpass->get();
+          required_mip_count =
+              std::max(required_mip_count, entity_pass->GetRequiredMipCount());
+        }
+        return true;
+      });
 
   ClipCoverageStack clip_coverage_stack = {ClipCoverageLayer{
       .coverage = Rect::MakeSize(root_render_target.GetRenderTargetSize()),
@@ -343,7 +353,7 @@ bool EntityPass::Render(ContentContext& renderer,
   // there's no need to set up a stencil attachment on the root render target.
   if (reads_from_onscreen_backdrop) {
     EntityPassTarget offscreen_target = CreateRenderTarget(
-        renderer, root_render_target.GetRenderTargetSize(), /*mip_count=*/4,
+        renderer, root_render_target.GetRenderTargetSize(), required_mip_count,
         GetClearColorOrDefault(render_target.GetRenderTargetSize()));
 
     if (!OnRender(renderer,  // renderer
@@ -1020,6 +1030,25 @@ void EntityPass::IterateAllElements(
   }
 }
 
+void EntityPass::IterateAllElements(
+    const std::function<bool(const Element&)>& iterator) const {
+  /// TODO(gaaclarke): Remove duplication here between const and non-const
+  /// versions.
+  if (!iterator) {
+    return;
+  }
+
+  for (auto& element : elements_) {
+    if (!iterator(element)) {
+      return;
+    }
+    if (auto subpass = std::get_if<std::unique_ptr<EntityPass>>(&element)) {
+      const EntityPass* entity_pass = subpass->get();
+      entity_pass->IterateAllElements(iterator);
+    }
+  }
+}
+
 void EntityPass::IterateAllEntities(
     const std::function<bool(Entity&)>& iterator) {
   if (!iterator) {
diff --git a/impeller/entity/entity_pass.h b/impeller/entity/entity_pass.h
index 39f5449ff323b..7de68d0d9ad11 100644
--- a/impeller/entity/entity_pass.h
+++ b/impeller/entity/entity_pass.h
@@ -101,6 +101,9 @@ class EntityPass {
   ///         it's included in the stream before its children.
   void IterateAllElements(const std::function<bool(Element&)>& iterator);
 
+  void IterateAllElements(
+      const std::function<bool(const Element&)>& iterator) const;
+
   //----------------------------------------------------------------------------
   /// @brief  Iterate all entities in this pass, recursively including entities
   ///         of child passes. The iteration order is depth-first.
@@ -148,6 +151,12 @@ class EntityPass {
 
   void SetEnableOffscreenCheckerboard(bool enabled);
 
+  int32_t GetRequiredMipCount() const { return required_mip_count_; }
+
+  void SetRequiredMipCount(int32_t mip_count) {
+    required_mip_count_ = mip_count;
+  }
+
   //----------------------------------------------------------------------------
   /// @brief  Computes the coverage of a given subpass. This is used to
   ///         determine the texture size of a given subpass before it's rendered
@@ -297,6 +306,7 @@ class EntityPass {
   std::optional<Rect> bounds_limit_;
   std::unique_ptr<EntityPassClipRecorder> clip_replay_ =
       std::make_unique<EntityPassClipRecorder>();
+  int32_t required_mip_count_ = 1;
 
   /// These values are incremented whenever something is added to the pass that
   /// requires reading from the backdrop texture. Currently, this can happen in
diff --git a/impeller/entity/entity_unittests.cc b/impeller/entity/entity_unittests.cc
index a24e8e2b59931..4bde8ea6799f7 100644
--- a/impeller/entity/entity_unittests.cc
+++ b/impeller/entity/entity_unittests.cc
@@ -48,6 +48,7 @@
 #include "impeller/renderer/command.h"
 #include "impeller/renderer/pipeline_descriptor.h"
 #include "impeller/renderer/render_pass.h"
+#include "impeller/renderer/testing/mocks.h"
 #include "impeller/renderer/vertex_buffer_builder.h"
 #include "impeller/typographer/backends/skia/text_frame_skia.h"
 #include "impeller/typographer/backends/skia/typographer_context_skia.h"

From 039b1b49027c4120cf907e56c56ad5ff72440793 Mon Sep 17 00:00:00 2001
From: Aaron Clarke <aaclarke@google.com>
Date: Thu, 11 Jan 2024 17:39:59 -0800
Subject: [PATCH 21/28] put the mipcount behind the flag for the new blur

---
 impeller/aiks/canvas.cc                             | 4 +++-
 impeller/entity/contents/filters/filter_contents.cc | 6 ++++++
 impeller/entity/contents/filters/filter_contents.h  | 2 ++
 3 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/impeller/aiks/canvas.cc b/impeller/aiks/canvas.cc
index 49c6851bd3284..f66da9a914cbf 100644
--- a/impeller/aiks/canvas.cc
+++ b/impeller/aiks/canvas.cc
@@ -136,7 +136,9 @@ void Canvas::Save() {
 namespace {
 class MipCountVisitor : public ImageFilterVisitor {
  public:
-  virtual void Visit(const BlurImageFilter& filter) { required_mip_count_ = 4; }
+  virtual void Visit(const BlurImageFilter& filter) {
+    required_mip_count_ = FilterContents::kBlurFilterRequiredMipCount;
+  }
   virtual void Visit(const LocalMatrixImageFilter& filter) {
     required_mip_count_ = 1;
   }
diff --git a/impeller/entity/contents/filters/filter_contents.cc b/impeller/entity/contents/filters/filter_contents.cc
index c4ffaff85726d..a9acd5ffd697d 100644
--- a/impeller/entity/contents/filters/filter_contents.cc
+++ b/impeller/entity/contents/filters/filter_contents.cc
@@ -52,6 +52,12 @@ std::shared_ptr<FilterContents> FilterContents::MakeDirectionalGaussianBlur(
 
 #define IMPELLER_ENABLE_NEW_GAUSSIAN_FILTER 1
 
+#ifdef IMPELLER_ENABLE_NEW_GAUSSIAN_FILTER
+const int32_t FilterContents::kBlurFilterRequiredMipCount = 4;
+#else
+const int32_t FilterContents::kBlurFilterRequiredMipCount = 1;
+#endif
+
 std::shared_ptr<FilterContents> FilterContents::MakeGaussianBlur(
     const FilterInput::Ref& input,
     Sigma sigma_x,
diff --git a/impeller/entity/contents/filters/filter_contents.h b/impeller/entity/contents/filters/filter_contents.h
index 3e210d8f0fb70..076593f644dab 100644
--- a/impeller/entity/contents/filters/filter_contents.h
+++ b/impeller/entity/contents/filters/filter_contents.h
@@ -20,6 +20,8 @@ namespace impeller {
 
 class FilterContents : public Contents {
  public:
+  static const int32_t kBlurFilterRequiredMipCount;
+
   enum class BlurStyle {
     /// Blurred inside and outside.
     kNormal,

From f13d449ee5379a007ff6d35f3aecb97372117b4b Mon Sep 17 00:00:00 2001
From: Aaron Clarke <aaclarke@google.com>
Date: Thu, 11 Jan 2024 18:57:48 -0800
Subject: [PATCH 22/28] added test

---
 impeller/aiks/aiks_unittests.cc               | 27 +++++++++++++++++++
 .../golden_playground_test_mac.cc             | 17 +++++++++++-
 2 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/impeller/aiks/aiks_unittests.cc b/impeller/aiks/aiks_unittests.cc
index e1f75aadc4099..620a59b19649f 100644
--- a/impeller/aiks/aiks_unittests.cc
+++ b/impeller/aiks/aiks_unittests.cc
@@ -3716,5 +3716,32 @@ TEST_P(AiksTest, SubpassWithClearColorOptimization) {
   // will be filled with NaNs and may produce a magenta texture on macOS or iOS.
   ASSERT_TRUE(OpenPlaygroundHere(canvas.EndRecordingAsPicture()));
 }
+
+TEST_P(AiksTest, GuassianBlurUpdatesMipmapContents) {
+  // This makes sure if mip maps are recycled across invocations of blurs the
+  // contents get updated each frame correctly. If they aren't updated the color
+  // inside the blur and outside the blur will be different.
+  //
+  // If there is some change to render target caching this could display a false
+  // positive in the future.
+  int32_t count = 0;
+  auto callback = [&](AiksContext& renderer) -> std::optional<Picture> {
+    Canvas canvas;
+    if (count++ == 0) {
+      canvas.DrawCircle({100, 100}, 50, {.color = Color::CornflowerBlue()});
+    } else {
+      canvas.DrawCircle({100, 100}, 50, {.color = Color::Chartreuse()});
+    }
+    canvas.ClipRRect(Rect::MakeLTRB(75, 50, 375, 275), {20, 20});
+    canvas.SaveLayer({.blend_mode = BlendMode::kSource}, std::nullopt,
+                     ImageFilter::MakeBlur(Sigma(30.0), Sigma(30.0),
+                                           FilterContents::BlurStyle::kNormal,
+                                           Entity::TileMode::kClamp));
+    canvas.Restore();
+    return canvas.EndRecordingAsPicture();
+  };
+
+  ASSERT_TRUE(OpenPlaygroundHere(callback));
+}
 }  // namespace testing
 }  // namespace impeller
diff --git a/impeller/golden_tests/golden_playground_test_mac.cc b/impeller/golden_tests/golden_playground_test_mac.cc
index 81cec2c283a10..ef7bff92ac2c1 100644
--- a/impeller/golden_tests/golden_playground_test_mac.cc
+++ b/impeller/golden_tests/golden_playground_test_mac.cc
@@ -55,6 +55,8 @@ static const std::vector<std::string> kSkipTests = {
     "impeller_Play_AiksTest_TextRotated_Vulkan",
     // Runtime stage based tests get confused with a Metal context.
     "impeller_Play_AiksTest_CanRenderClippedRuntimeEffects_Vulkan",
+    "impeller_Play_AiksTest_CaptureContext_Metal",
+    "impeller_Play_AiksTest_CaptureContext_Vulkan",
 };
 
 namespace {
@@ -153,7 +155,20 @@ bool GoldenPlaygroundTest::OpenPlaygroundHere(Picture picture) {
 bool GoldenPlaygroundTest::OpenPlaygroundHere(
     AiksPlaygroundCallback
         callback) {  // NOLINT(performance-unnecessary-value-param)
-  return false;
+  AiksContext renderer(GetContext(), typographer_context_);
+
+  std::optional<Picture> picture;
+  std::unique_ptr<testing::MetalScreenshot> screenshot;
+  for (int i = 0; i < 2; ++i) {
+    picture = callback(renderer);
+    if (!picture.has_value()) {
+      return false;
+    }
+    screenshot = pimpl_->screenshotter->MakeScreenshot(
+        renderer, picture.value(), pimpl_->window_size);
+  }
+
+  return SaveScreenshot(std::move(screenshot));
 }
 
 std::shared_ptr<Texture> GoldenPlaygroundTest::CreateTextureForFixture(

From 345cb30529e7fddbceb826243142b53a01e712fe Mon Sep 17 00:00:00 2001
From: Aaron Clarke <aaclarke@google.com>
Date: Thu, 11 Jan 2024 19:06:08 -0800
Subject: [PATCH 23/28] turned off hack

---
 impeller/entity/contents/filters/filter_contents.cc | 2 --
 1 file changed, 2 deletions(-)

diff --git a/impeller/entity/contents/filters/filter_contents.cc b/impeller/entity/contents/filters/filter_contents.cc
index a9acd5ffd697d..235a53134c5e3 100644
--- a/impeller/entity/contents/filters/filter_contents.cc
+++ b/impeller/entity/contents/filters/filter_contents.cc
@@ -50,8 +50,6 @@ std::shared_ptr<FilterContents> FilterContents::MakeDirectionalGaussianBlur(
   return blur;
 }
 
-#define IMPELLER_ENABLE_NEW_GAUSSIAN_FILTER 1
-
 #ifdef IMPELLER_ENABLE_NEW_GAUSSIAN_FILTER
 const int32_t FilterContents::kBlurFilterRequiredMipCount = 4;
 #else

From b04debfaecdf08e195d3e14230cd954ee80f26bd Mon Sep 17 00:00:00 2001
From: Aaron Clarke <aaclarke@google.com>
Date: Thu, 11 Jan 2024 20:26:47 -0800
Subject: [PATCH 24/28] fixed linux usage of mip_count

---
 impeller/entity/contents/scene_contents.cc | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/impeller/entity/contents/scene_contents.cc b/impeller/entity/contents/scene_contents.cc
index 54eb9f5cd29a4..5a0b68cd427e8 100644
--- a/impeller/entity/contents/scene_contents.cc
+++ b/impeller/entity/contents/scene_contents.cc
@@ -50,6 +50,7 @@ bool SceneContents::Render(const ContentContext& renderer,
         *renderer.GetContext(),             // context
         *renderer.GetRenderTargetCache(),   // allocator
         ISize(coverage.value().GetSize()),  // size
+        /*mip_count=*/1,
         "SceneContents",                    // label
         RenderTarget::AttachmentConfigMSAA{
             .storage_mode = StorageMode::kDeviceTransient,
@@ -68,6 +69,7 @@ bool SceneContents::Render(const ContentContext& renderer,
         *renderer.GetContext(),             // context
         *renderer.GetRenderTargetCache(),   // allocator
         ISize(coverage.value().GetSize()),  // size
+        /*mip_count=*/1,
         "SceneContents",                    // label
         RenderTarget::AttachmentConfig{
             .storage_mode = StorageMode::kDevicePrivate,

From 12a1d30ac709a9aa868a132d44ccaf0dd8fc3d02 Mon Sep 17 00:00:00 2001
From: Aaron Clarke <aaclarke@google.com>
Date: Thu, 11 Jan 2024 20:35:24 -0800
Subject: [PATCH 25/28] added another test for setting mip count levels

---
 impeller/aiks/aiks_unittests.cc | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/impeller/aiks/aiks_unittests.cc b/impeller/aiks/aiks_unittests.cc
index 620a59b19649f..91077989b7239 100644
--- a/impeller/aiks/aiks_unittests.cc
+++ b/impeller/aiks/aiks_unittests.cc
@@ -3743,5 +3743,29 @@ TEST_P(AiksTest, GuassianBlurUpdatesMipmapContents) {
 
   ASSERT_TRUE(OpenPlaygroundHere(callback));
 }
+
+TEST_P(AiksTest, GuassianBlurSetsMipCountOnPass) {
+  Canvas canvas;
+  canvas.DrawCircle({100, 100}, 50, {.color = Color::CornflowerBlue()});
+  canvas.SaveLayer({}, std::nullopt,
+                   ImageFilter::MakeBlur(Sigma(3), Sigma(3),
+                                         FilterContents::BlurStyle::kNormal,
+                                         Entity::TileMode::kClamp));
+  canvas.Restore();
+
+  Picture picture = canvas.EndRecordingAsPicture();
+
+  int32_t max_mip_count = 1;
+  picture.pass->IterateAllElements([&](EntityPass::Element& element) -> bool {
+    if (auto subpass = std::get_if<std::unique_ptr<EntityPass>>(&element)) {
+      max_mip_count =
+          std::max(max_mip_count, subpass->get()->GetRequiredMipCount());
+    }
+    return true;
+  });
+
+  EXPECT_EQ(1, max_mip_count);
+}
+
 }  // namespace testing
 }  // namespace impeller

From 4bea7dc29fc71fa6469cf645fcf381e4e69943e3 Mon Sep 17 00:00:00 2001
From: Aaron Clarke <aaclarke@google.com>
Date: Fri, 12 Jan 2024 08:49:25 -0800
Subject: [PATCH 26/28] added another test

---
 impeller/aiks/aiks_context.cc              |  8 ++++--
 impeller/aiks/aiks_context.h               |  6 ++++-
 impeller/aiks/aiks_unittests.cc            | 30 ++++++++++++++++++++--
 impeller/entity/contents/scene_contents.cc |  4 +--
 impeller/entity/render_target_cache.h      | 11 ++++++++
 5 files changed, 52 insertions(+), 7 deletions(-)

diff --git a/impeller/aiks/aiks_context.cc b/impeller/aiks/aiks_context.cc
index d001c189e3b0d..3be53f953713b 100644
--- a/impeller/aiks/aiks_context.cc
+++ b/impeller/aiks/aiks_context.cc
@@ -12,14 +12,18 @@ namespace impeller {
 
 AiksContext::AiksContext(
     std::shared_ptr<Context> context,
-    std::shared_ptr<TypographerContext> typographer_context)
+    std::shared_ptr<TypographerContext> typographer_context,
+    std::optional<std::shared_ptr<RenderTargetAllocator>>
+        render_target_allocator)
     : context_(std::move(context)) {
   if (!context_ || !context_->IsValid()) {
     return;
   }
 
   content_context_ = std::make_unique<ContentContext>(
-      context_, std::move(typographer_context));
+      context_, std::move(typographer_context),
+      render_target_allocator.has_value() ? render_target_allocator.value()
+                                          : nullptr);
   if (!content_context_->IsValid()) {
     return;
   }
diff --git a/impeller/aiks/aiks_context.h b/impeller/aiks/aiks_context.h
index ad8d6429c4d01..5b35b63def700 100644
--- a/impeller/aiks/aiks_context.h
+++ b/impeller/aiks/aiks_context.h
@@ -28,8 +28,12 @@ class AiksContext {
   ///                             `nullptr` is supplied, then attempting to draw
   ///                             text with Aiks will result in validation
   ///                             errors.
+  /// @param render_target_allocator Injects a render target allocator or
+  ///                                allocates its own if none is supplied.
   AiksContext(std::shared_ptr<Context> context,
-              std::shared_ptr<TypographerContext> typographer_context);
+              std::shared_ptr<TypographerContext> typographer_context,
+              std::optional<std::shared_ptr<RenderTargetAllocator>>
+                  render_target_allocator = std::nullopt);
 
   ~AiksContext();
 
diff --git a/impeller/aiks/aiks_unittests.cc b/impeller/aiks/aiks_unittests.cc
index 91077989b7239..b0c5f057264bf 100644
--- a/impeller/aiks/aiks_unittests.cc
+++ b/impeller/aiks/aiks_unittests.cc
@@ -4,6 +4,7 @@
 
 #include "flutter/impeller/aiks/aiks_unittests.h"
 
+#include <algorithm>
 #include <array>
 #include <cmath>
 #include <cstdlib>
@@ -26,6 +27,7 @@
 #include "impeller/entity/contents/radial_gradient_contents.h"
 #include "impeller/entity/contents/solid_color_contents.h"
 #include "impeller/entity/contents/sweep_gradient_contents.h"
+#include "impeller/entity/render_target_cache.h"
 #include "impeller/geometry/color.h"
 #include "impeller/geometry/constants.h"
 #include "impeller/geometry/geometry_asserts.h"
@@ -3744,7 +3746,7 @@ TEST_P(AiksTest, GuassianBlurUpdatesMipmapContents) {
   ASSERT_TRUE(OpenPlaygroundHere(callback));
 }
 
-TEST_P(AiksTest, GuassianBlurSetsMipCountOnPass) {
+TEST_P(AiksTest, GaussianBlurSetsMipCountOnPass) {
   Canvas canvas;
   canvas.DrawCircle({100, 100}, 50, {.color = Color::CornflowerBlue()});
   canvas.SaveLayer({}, std::nullopt,
@@ -3755,7 +3757,7 @@ TEST_P(AiksTest, GuassianBlurSetsMipCountOnPass) {
 
   Picture picture = canvas.EndRecordingAsPicture();
 
-  int32_t max_mip_count = 1;
+  int32_t max_mip_count = 0;
   picture.pass->IterateAllElements([&](EntityPass::Element& element) -> bool {
     if (auto subpass = std::get_if<std::unique_ptr<EntityPass>>(&element)) {
       max_mip_count =
@@ -3767,5 +3769,29 @@ TEST_P(AiksTest, GuassianBlurSetsMipCountOnPass) {
   EXPECT_EQ(1, max_mip_count);
 }
 
+TEST_P(AiksTest, GaussianBlurAllocatesCorrectMipCountRenderTarget) {
+  Canvas canvas;
+  canvas.DrawCircle({100, 100}, 50, {.color = Color::CornflowerBlue()});
+  canvas.SaveLayer({}, std::nullopt,
+                   ImageFilter::MakeBlur(Sigma(3), Sigma(3),
+                                         FilterContents::BlurStyle::kNormal,
+                                         Entity::TileMode::kClamp));
+  canvas.Restore();
+
+  Picture picture = canvas.EndRecordingAsPicture();
+  std::shared_ptr<RenderTargetCache> cache =
+      std::make_shared<RenderTargetCache>(GetContext()->GetResourceAllocator());
+  AiksContext aiks_context(GetContext(), nullptr, cache);
+  picture.ToImage(aiks_context, {100, 100});
+
+  size_t max_mip_count = 0;
+  for (auto it = cache->GetTextureDataBegin(); it != cache->GetTextureDataEnd();
+       ++it) {
+    max_mip_count =
+        std::max(it->texture->GetTextureDescriptor().mip_count, max_mip_count);
+  }
+  EXPECT_EQ(max_mip_count, 1lu);
+}
+
 }  // namespace testing
 }  // namespace impeller
diff --git a/impeller/entity/contents/scene_contents.cc b/impeller/entity/contents/scene_contents.cc
index 5a0b68cd427e8..f5da62830ecbc 100644
--- a/impeller/entity/contents/scene_contents.cc
+++ b/impeller/entity/contents/scene_contents.cc
@@ -51,7 +51,7 @@ bool SceneContents::Render(const ContentContext& renderer,
         *renderer.GetRenderTargetCache(),   // allocator
         ISize(coverage.value().GetSize()),  // size
         /*mip_count=*/1,
-        "SceneContents",                    // label
+        "SceneContents",  // label
         RenderTarget::AttachmentConfigMSAA{
             .storage_mode = StorageMode::kDeviceTransient,
             .resolve_storage_mode = StorageMode::kDevicePrivate,
@@ -70,7 +70,7 @@ bool SceneContents::Render(const ContentContext& renderer,
         *renderer.GetRenderTargetCache(),   // allocator
         ISize(coverage.value().GetSize()),  // size
         /*mip_count=*/1,
-        "SceneContents",                    // label
+        "SceneContents",  // label
         RenderTarget::AttachmentConfig{
             .storage_mode = StorageMode::kDevicePrivate,
             .load_action = LoadAction::kClear,
diff --git a/impeller/entity/render_target_cache.h b/impeller/entity/render_target_cache.h
index b59bd43983711..382781b793b7b 100644
--- a/impeller/entity/render_target_cache.h
+++ b/impeller/entity/render_target_cache.h
@@ -43,6 +43,17 @@ class RenderTargetCache : public RenderTargetAllocator {
   RenderTargetCache(const RenderTargetCache&) = delete;
 
   RenderTargetCache& operator=(const RenderTargetCache&) = delete;
+
+ public:
+  /// Visible for testing.
+  std::vector<TextureData>::const_iterator GetTextureDataBegin() const {
+    return texture_data_.begin();
+  }
+
+  /// Visible for testing.
+  std::vector<TextureData>::const_iterator GetTextureDataEnd() const {
+    return texture_data_.end();
+  }
 };
 
 }  // namespace impeller

From 9bf4355ba78d0766106e9365bdb450bc3ee846e9 Mon Sep 17 00:00:00 2001
From: Aaron Clarke <aaclarke@google.com>
Date: Fri, 12 Jan 2024 08:52:28 -0800
Subject: [PATCH 27/28] removed todo

---
 impeller/entity/shaders/gaussian_blur/kernel.glsl | 1 -
 1 file changed, 1 deletion(-)

diff --git a/impeller/entity/shaders/gaussian_blur/kernel.glsl b/impeller/entity/shaders/gaussian_blur/kernel.glsl
index c491acbbb0fc4..d8a544bf070f6 100644
--- a/impeller/entity/shaders/gaussian_blur/kernel.glsl
+++ b/impeller/entity/shaders/gaussian_blur/kernel.glsl
@@ -22,7 +22,6 @@ blur_info;
 
 f16vec4 Sample(f16sampler2D tex, vec2 coords) {
 #if ENABLE_DECAL_SPECIALIZATION
-  // TODO(gaaclarke): Make a LOD variant here.
   return IPHalfSampleDecal(tex, coords);
 #else
   return texture(tex, coords);

From 7cba038210052527b0f67b38abe7ac9073fda77f Mon Sep 17 00:00:00 2001
From: Aaron Clarke <aaclarke@google.com>
Date: Fri, 12 Jan 2024 08:58:52 -0800
Subject: [PATCH 28/28] updated comment

---
 impeller/aiks/aiks_unittests.cc | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/impeller/aiks/aiks_unittests.cc b/impeller/aiks/aiks_unittests.cc
index b0c5f057264bf..c2b07397610a1 100644
--- a/impeller/aiks/aiks_unittests.cc
+++ b/impeller/aiks/aiks_unittests.cc
@@ -3725,7 +3725,8 @@ TEST_P(AiksTest, GuassianBlurUpdatesMipmapContents) {
   // inside the blur and outside the blur will be different.
   //
   // If there is some change to render target caching this could display a false
-  // positive in the future.
+  // positive in the future.  Also, if the LOD that is rendered is 1 it could
+  // present a false positive.
   int32_t count = 0;
   auto callback = [&](AiksContext& renderer) -> std::optional<Picture> {
     Canvas canvas;