[Impeller] Add support for VK_EXT_blend_operation_advanced.

impeller/core/formats.h

@@ -502,6 +502,13 @@ struct ColorAttachmentDescriptor {
   BlendOperation alpha_blend_op = BlendOperation::kAdd;
   BlendFactor dst_alpha_blend_factor = BlendFactor::kOneMinusSourceAlpha;
 
+  /// @brief If the advanced blend override is specified, then all other fields
+  ///        are ignored.
+  ///
+  ///        This is only valid if the platform has native support for advanced
+  ///        blend modes.
+  std::optional<BlendMode> advanced_blend_override = std::nullopt;
+
   std::underlying_type_t<ColorWriteMask> write_mask =
       static_cast<uint64_t>(ColorWriteMask::kAll);
 
@@ -514,14 +521,17 @@ struct ColorAttachmentDescriptor {
            src_alpha_blend_factor == o.src_alpha_blend_factor &&  //
            alpha_blend_op == o.alpha_blend_op &&                  //
            dst_alpha_blend_factor == o.dst_alpha_blend_factor &&  //
-           write_mask == o.write_mask;
+           write_mask == o.write_mask &&                          //
+           advanced_blend_override.value_or(BlendMode::kClear) ==
+               o.advanced_blend_override.value_or(BlendMode::kClear);
   }
 
   constexpr size_t Hash() const {
-    return fml::HashCombine(format, blending_enabled, src_color_blend_factor,
-                            color_blend_op, dst_color_blend_factor,
-                            src_alpha_blend_factor, alpha_blend_op,
-                            dst_alpha_blend_factor, write_mask);
+    return fml::HashCombine(
+        format, blending_enabled, src_color_blend_factor, color_blend_op,
+        dst_color_blend_factor, src_alpha_blend_factor, alpha_blend_op,
+        dst_alpha_blend_factor, write_mask,
+        advanced_blend_override.value_or(BlendMode::kClear));
   }
 };
 

impeller/entity/contents/content_context.cc

@@ -9,7 +9,6 @@
 #include "impeller/base/strings.h"
 #include "impeller/core/formats.h"
 #include "impeller/entity/contents/framebuffer_blend_contents.h"
-#include "impeller/entity/entity.h"
 #include "impeller/entity/render_target_cache.h"
 #include "impeller/renderer/command_buffer.h"
 #include "impeller/renderer/pipeline_descriptor.h"
@@ -23,14 +22,8 @@ namespace impeller {
 void ContentContextOptions::ApplyToPipelineDescriptor(
     PipelineDescriptor& desc) const {
   auto pipeline_blend = blend_mode;
-  if (blend_mode > Entity::kLastPipelineBlendMode) {
-    VALIDATION_LOG << "Cannot use blend mode " << static_cast<int>(blend_mode)
-                   << " as a pipeline blend.";
-    pipeline_blend = BlendMode::kSourceOver;
-  }
 
   desc.SetSampleCount(sample_count);
-
   ColorAttachmentDescriptor color0 = *desc.GetColorAttachmentDescriptor(0u);
   color0.format = color_attachment_pixel_format;
   color0.alpha_blend_op = BlendOperation::kAdd;
@@ -132,7 +125,13 @@ void ContentContextOptions::ApplyToPipelineDescriptor(
       color0.src_color_blend_factor = BlendFactor::kZero;
       break;
     default:
-      FML_UNREACHABLE();
+      // This is an advanced blend, set the override.
+      color0.advanced_blend_override = blend_mode;
+      color0.dst_alpha_blend_factor = BlendFactor::kOne;
+      color0.dst_color_blend_factor = BlendFactor::kOne;
+      color0.src_alpha_blend_factor = BlendFactor::kOne;
+      color0.src_color_blend_factor = BlendFactor::kOne;
+      break;
   }
   desc.SetColorAttachmentDescriptor(0u, color0);
 
@@ -149,7 +148,6 @@ void ContentContextOptions::ApplyToPipelineDescriptor(
   }
 
   desc.SetPrimitiveType(primitive_type);
-
   desc.SetPolygonMode(wireframe ? PolygonMode::kLine : PolygonMode::kFill);
 }
 

impeller/entity/contents/content_context.h

@@ -12,7 +12,6 @@
 #include "flutter/fml/build_config.h"
 #include "flutter/fml/hash_combine.h"
 #include "flutter/fml/logging.h"
-#include "flutter/fml/macros.h"
 #include "impeller/base/validation.h"
 #include "impeller/core/formats.h"
 #include "impeller/entity/entity.h"

impeller/entity/entity_pass.cc

@@ -293,10 +293,12 @@ static EntityPassTarget CreateRenderTarget(ContentContext& renderer,
 }
 
 uint32_t EntityPass::GetTotalPassReads(ContentContext& renderer) const {
-  return renderer.GetDeviceCapabilities().SupportsFramebufferFetch()
-             ? backdrop_filter_reads_from_pass_texture_
-             : backdrop_filter_reads_from_pass_texture_ +
-                   advanced_blend_reads_from_pass_texture_;
+  if (renderer.GetDeviceCapabilities().SupportsFramebufferFetch() ||
+      renderer.GetDeviceCapabilities().SupportsNativeAdvancedBlends()) {
+    return backdrop_filter_reads_from_pass_texture_;
+  }
+  return backdrop_filter_reads_from_pass_texture_ +
+         advanced_blend_reads_from_pass_texture_;
 }
 
 bool EntityPass::Render(ContentContext& renderer,
@@ -915,7 +917,10 @@ bool EntityPass::OnRender(
     ///
 
     if (result.entity.GetBlendMode() > Entity::kLastPipelineBlendMode) {
-      if (renderer.GetDeviceCapabilities().SupportsFramebufferFetch()) {
+      if (renderer.GetDeviceCapabilities().SupportsNativeAdvancedBlends()) {
+        // If native support for advanced blends is present, pass the entity
+        // through as-is.
+      } else if (renderer.GetDeviceCapabilities().SupportsFramebufferFetch()) {
         auto src_contents = result.entity.GetContents();
         auto contents = std::make_shared<FramebufferBlendContents>();
         contents->SetChildContents(src_contents);

impeller/renderer/backend/gles/capabilities_gles.cc

@@ -176,6 +176,10 @@ bool CapabilitiesGLES::SupportsDeviceTransientTextures() const {
   return false;
 }
 
+bool CapabilitiesGLES::SupportsNativeAdvancedBlends() const {
+  return false;
+}
+
 PixelFormat CapabilitiesGLES::GetDefaultColorFormat() const {
   return PixelFormat::kR8G8B8A8UNormInt;
 }

impeller/renderer/backend/gles/capabilities_gles.h

@@ -106,6 +106,9 @@ class CapabilitiesGLES final
   // |Capabilities|
   bool SupportsDeviceTransientTextures() const override;
 
+  // |Capabilities|
+  bool SupportsNativeAdvancedBlends() const override;
+
   // |Capabilities|
   PixelFormat GetDefaultColorFormat() const override;
 

impeller/renderer/backend/gles/proc_table_gles.h

@@ -110,6 +110,7 @@ struct GLProc {
   PROC(BindTexture);                         \
   PROC(BlendEquationSeparate);               \
   PROC(BlendFuncSeparate);                   \
+  PROC(BlendEquation);                       \
   PROC(BufferData);                          \
   PROC(CheckFramebufferStatus);              \
   PROC(Clear);                               \

impeller/renderer/backend/gles/render_pass_gles.cc

@@ -12,6 +12,7 @@
 #include "fml/logging.h"
 #include "impeller/base/validation.h"
 #include "impeller/core/texture_descriptor.h"
+#include "impeller/geometry/color.h"
 #include "impeller/renderer/backend/gles/context_gles.h"
 #include "impeller/renderer/backend/gles/device_buffer_gles.h"
 #include "impeller/renderer/backend/gles/formats_gles.h"
@@ -44,6 +45,7 @@ void RenderPassGLES::OnSetLabel(std::string label) {
 void ConfigureBlending(const ProcTableGLES& gl,
                        const ColorAttachmentDescriptor* color) {
   if (color->blending_enabled) {
+    FML_DCHECK(!color->advanced_blend_override.has_value());
     gl.Enable(GL_BLEND);
     gl.BlendFuncSeparate(
         ToBlendFactor(color->src_color_blend_factor),  // src color

impeller/renderer/backend/metal/context_mtl.mm

@@ -68,6 +68,7 @@ static bool DeviceSupportsComputeSubgroups(id<MTLDevice> device) {
       .SetSupportsComputeSubgroups(DeviceSupportsComputeSubgroups(device))
       .SetSupportsReadFromResolve(true)
       .SetSupportsDeviceTransientTextures(true)
+      .SetSupportsNativeAdvancedBlends(false)
       .Build();
 }
 

impeller/renderer/backend/vulkan/allocator_vk.cc

@@ -172,6 +172,7 @@ static constexpr vk::ImageUsageFlags ToVKImageUsageFlags(
     bool supports_memoryless_textures,
     bool supports_framebuffer_fetch) {
   vk::ImageUsageFlags vk_usage;
+  bool supports_advanced_blends = true;
 
   switch (mode) {
     case StorageMode::kHostVisible:
@@ -192,6 +193,8 @@ static constexpr vk::ImageUsageFlags ToVKImageUsageFlags(
     }
     if (supports_framebuffer_fetch) {
       vk_usage |= vk::ImageUsageFlagBits::eInputAttachment;
+    } else if (supports_advanced_blends) {
+      vk_usage |= vk::ImageUsageFlagBits::eInputAttachment;
     }
   }
 

impeller/renderer/backend/vulkan/capabilities_vk.cc

@@ -157,6 +157,8 @@ static const char* GetDeviceExtensionName(OptionalDeviceExtensionVK ext) {
   switch (ext) {
     case OptionalDeviceExtensionVK::kEXTPipelineCreationFeedback:
       return VK_EXT_PIPELINE_CREATION_FEEDBACK_EXTENSION_NAME;
+    case OptionalDeviceExtensionVK::kEXTBlendOperationAdvanced:
+      return VK_EXT_BLEND_OPERATION_ADVANCED_EXTENSION_NAME;
     case OptionalDeviceExtensionVK::kARMRasterizationOrderAttachmentAccess:
       return VK_ARM_RASTERIZATION_ORDER_ATTACHMENT_ACCESS_EXTENSION_NAME;
     case OptionalDeviceExtensionVK::kEXTRasterizationOrderAttachmentAccess:
@@ -363,9 +365,9 @@ bool CapabilitiesVK::SetPhysicalDevice(const vk::PhysicalDevice& device) {
 
   device_properties_ = device.getProperties();
 
-  auto physical_properties_2 =
-      device.getProperties2<vk::PhysicalDeviceProperties2,
-                            vk::PhysicalDeviceSubgroupProperties>();
+  auto physical_properties_2 = device.getProperties2<
+      vk::PhysicalDeviceProperties2, vk::PhysicalDeviceSubgroupProperties,
+      vk::PhysicalDeviceBlendOperationAdvancedPropertiesEXT>();
 
   // Currently shaders only want access to arithmetic subgroup features.
   // If that changes this needs to get updated, and so does Metal (which right
@@ -407,6 +409,10 @@ bool CapabilitiesVK::SetPhysicalDevice(const vk::PhysicalDevice& device) {
   }
 
   {
+    supports_native_advanced_blends_ =
+        optional_device_extensions_.find(
+            OptionalDeviceExtensionVK::kEXTBlendOperationAdvanced) !=
+        optional_device_extensions_.end();
     supports_framebuffer_fetch_ =
         (optional_device_extensions_.find(
              OptionalDeviceExtensionVK::
@@ -472,6 +478,10 @@ bool CapabilitiesVK::SupportsDecalSamplerAddressMode() const {
   return true;
 }
 
+bool CapabilitiesVK::SupportsNativeAdvancedBlends() const {
+  return supports_native_advanced_blends_;
+}
+
 // |Capabilities|
 bool CapabilitiesVK::SupportsDeviceTransientTextures() const {
   return supports_device_transient_textures_;

impeller/renderer/backend/vulkan/capabilities_vk.h

@@ -21,6 +21,8 @@ class ContextVK;
 enum class OptionalDeviceExtensionVK : uint32_t {
   // https://registry.khronos.org/vulkan/specs/1.3-extensions/man/html/VK_EXT_pipeline_creation_feedback.html
   kEXTPipelineCreationFeedback,
+  // https://registry.khronos.org/vulkan/specs/1.3-extensions/man/html/VK_EXT_blend_operation_advanced.html
+  kEXTBlendOperationAdvanced,
   kARMRasterizationOrderAttachmentAccess,
   kEXTRasterizationOrderAttachmentAccess,
   kLast,
@@ -92,6 +94,9 @@ class CapabilitiesVK final : public Capabilities,
   // |Capabilities|
   bool SupportsDeviceTransientTextures() const override;
 
+  // |Capabilities|
+  bool SupportsNativeAdvancedBlends() const override;
+
   // |Capabilities|
   PixelFormat GetDefaultColorFormat() const override;
 
@@ -111,6 +116,7 @@ class CapabilitiesVK final : public Capabilities,
   vk::PhysicalDeviceProperties device_properties_;
   bool supports_compute_subgroups_ = false;
   bool supports_device_transient_textures_ = false;
+  bool supports_native_advanced_blends_ = false;
   bool supports_framebuffer_fetch_ = false;
   bool is_valid_ = false;
 

impeller/renderer/backend/vulkan/formats_vk.h

@@ -73,6 +73,45 @@ constexpr vk::BlendOp ToVKBlendOp(BlendOperation op) {
   FML_UNREACHABLE();
 }
 
+constexpr vk::BlendOp ToAdvancedVKBlendOp(BlendMode blend_mode) {
+  switch (blend_mode) {
+    case BlendMode::kScreen:
+      return vk::BlendOp::eScreenEXT;
+    case BlendMode::kOverlay:
+      return vk::BlendOp::eOverlayEXT;
+    case BlendMode::kDarken:
+      return vk::BlendOp::eDarkenEXT;
+    case BlendMode::kLighten:
+      return vk::BlendOp::eLightenEXT;
+    case BlendMode::kColorDodge:
+      return vk::BlendOp::eColordodgeEXT;
+    case BlendMode::kColorBurn:
+      return vk::BlendOp::eColorburnEXT;
+    case BlendMode::kHardLight:
+      return vk::BlendOp::eHardlightEXT;
+    case BlendMode::kSoftLight:
+      return vk::BlendOp::eSoftlightEXT;
+    case BlendMode::kDifference:
+      return vk::BlendOp::eDifferenceEXT;
+    case BlendMode::kExclusion:
+      return vk::BlendOp::eExclusionEXT;
+    case BlendMode::kMultiply:
+      return vk::BlendOp::eMultiplyEXT;
+    case BlendMode::kHue:
+      return vk::BlendOp::eHslHueEXT;
+    case BlendMode::kSaturation:
+      return vk::BlendOp::eHslSaturationEXT;
+    case BlendMode::kColor:
+      return vk::BlendOp::eHslColorEXT;
+    case BlendMode::kLuminosity:
+      return vk::BlendOp::eHslLuminosityEXT;
+      break;
+    default:
+      break;
+  }
+  FML_UNREACHABLE();
+}
+
 constexpr vk::ColorComponentFlags ToVKColorComponentFlags(
     std::underlying_type_t<ColorWriteMask> type) {
   using UnderlyingType = decltype(type);
@@ -105,13 +144,24 @@ ToVKPipelineColorBlendAttachmentState(const ColorAttachmentDescriptor& desc) {
   res.setBlendEnable(desc.blending_enabled);
 
   res.setSrcColorBlendFactor(ToVKBlendFactor(desc.src_color_blend_factor));
-  res.setColorBlendOp(ToVKBlendOp(desc.color_blend_op));
-  res.setDstColorBlendFactor(ToVKBlendFactor(desc.dst_color_blend_factor));
+  if (desc.advanced_blend_override.has_value()) {
+    res.setColorBlendOp(
+        ToAdvancedVKBlendOp(desc.advanced_blend_override.value()));
+  } else {
+    res.setColorBlendOp(ToVKBlendOp(desc.color_blend_op));
+  }
 
+  res.setDstColorBlendFactor(ToVKBlendFactor(desc.dst_color_blend_factor));
   res.setSrcAlphaBlendFactor(ToVKBlendFactor(desc.src_alpha_blend_factor));
-  res.setAlphaBlendOp(ToVKBlendOp(desc.alpha_blend_op));
-  res.setDstAlphaBlendFactor(ToVKBlendFactor(desc.dst_alpha_blend_factor));
 
+  if (desc.advanced_blend_override.has_value()) {
+    res.setAlphaBlendOp(
+        ToAdvancedVKBlendOp(desc.advanced_blend_override.value()));
+  } else {
+    res.setAlphaBlendOp(ToVKBlendOp(desc.alpha_blend_op));
+  }
+
+  res.setDstAlphaBlendFactor(ToVKBlendFactor(desc.dst_alpha_blend_factor));
   res.setColorWriteMask(ToVKColorComponentFlags(desc.write_mask));
 
   return res;

impeller/renderer/backend/vulkan/pipeline_library_vk.cc

@@ -86,6 +86,7 @@ static vk::UniqueRenderPass CreateCompatRenderPassForPipeline(
     bool supports_framebuffer_fetch) {
   std::vector<vk::AttachmentDescription> attachments;
 
+  bool supports_advanced_blend = true;
   std::vector<vk::AttachmentReference> color_refs;
   std::vector<vk::AttachmentReference> subpass_color_ref;
   vk::AttachmentReference depth_stencil_ref = kUnusedAttachmentReference;
@@ -137,6 +138,24 @@ static vk::UniqueRenderPass CreateCompatRenderPassForPipeline(
   subpass_desc.setColorAttachments(color_refs);
   subpass_desc.setPDepthStencilAttachment(&depth_stencil_ref);
 
+  // See
+  // https://github.com/google/angle/blob/46817856888e74d23169e79ac98064600fd00127/src/libANGLE/renderer/vulkan/vk_cache_utils.cpp#L672-L693
+  if (supports_advanced_blend) {
+    vk::SubpassDependency subpass_dependency;
+    subpass_dependency.setSrcSubpass(0);
+    subpass_dependency.setDstSubpass(0);
+    subpass_dependency.dependencyFlags = vk::DependencyFlagBits::eByRegion;
+    subpass_dependency.srcStageMask =
+        vk::PipelineStageFlagBits::eColorAttachmentOutput;
+    subpass_dependency.srcAccessMask =
+        vk::AccessFlagBits::eColorAttachmentWrite;
+    subpass_dependency.dstStageMask =
+        vk::PipelineStageFlagBits::eColorAttachmentOutput;
+    subpass_dependency.dstAccessMask =
+        vk::AccessFlagBits::eColorAttachmentReadNoncoherentEXT;
+    subpass_dependencies.emplace_back(subpass_dependency);
+  }
+
   vk::RenderPassCreateInfo render_pass_desc;
   render_pass_desc.setAttachments(attachments);
   render_pass_desc.setPSubpasses(&subpass_desc);
@@ -383,6 +402,15 @@ std::unique_ptr<PipelineVK> PipelineLibraryVK::CreatePipeline(
   blend_state.setAttachments(attachment_blend_state);
   pipeline_info.setPColorBlendState(&blend_state);
 
+  // vk::PipelineColorBlendAdvancedStateCreateInfoEXT state;
+  // if (desc.GetColorAttachmentDescriptors()
+  //         .find(0u)
+  //         ->second.advanced_blend_override.has_value()) {
+  //   state.setBlendOverlap(vk::BlendOverlapEXT::eUncorrelated);  // dunno
+  //   state.setSrcPremultiplied(true);                            // double
+  //   check state.setDstPremultiplied(true); blend_state.pNext = &state;
+  // }
+
   std::shared_ptr<DeviceHolder> strong_device = device_holder_.lock();
   if (!strong_device) {
     return nullptr;