Raycasting

Cargo.toml

@@ -126,6 +126,10 @@ path = "examples/3d/texture.rs"
 name = "z_sort_debug"
 path = "examples/3d/z_sort_debug.rs"
 
+[[example]]
+name = "raycast"
+path = "examples/physics/raycast.rs"
+
 [[example]]
 name = "custom_loop"
 path = "examples/app/custom_loop.rs"

crates/bevy_internal/Cargo.toml

@@ -46,6 +46,7 @@ bevy_input = { path = "../bevy_input", version = "0.3.0" }
 bevy_log = { path = "../bevy_log", version = "0.3.0" }
 bevy_math = { path = "../bevy_math", version = "0.3.0" }
 bevy_reflect = { path = "../bevy_reflect", version = "0.3.0", features = ["bevy"] }
+bevy_physics = { path = "../bevy_physics", version = "0.3.0" }
 bevy_scene = { path = "../bevy_scene", version = "0.3.0" }
 bevy_transform = { path = "../bevy_transform", version = "0.3.0" }
 bevy_utils = { path = "../bevy_utils", version = "0.3.0" }

crates/bevy_internal/src/lib.rs

@@ -44,6 +44,11 @@ pub mod math {
     pub use bevy_math::*;
 }
 
+pub mod physics {
+    //! colliders and raycasting
+    pub use bevy_physics::*;
+}
+
 pub mod reflect {
     // TODO: remove these renames once TypeRegistryArc is no longer required
     //! Type reflection used for dynamically interacting with rust types.

crates/bevy_physics/Cargo.toml

@@ -0,0 +1,23 @@
+[package]
+name = "bevy_physics"
+version = "0.3.0"
+edition = "2018"
+authors = [
+    "Bevy Contributors <[email protected]>",
+    "Carter Anderson <[email protected]>",
+]
+description = "Provides physics functionality for Bevy Engine"
+homepage = "https://bevyengine.org"
+repository = "https://github.com/bevyengine/bevy"
+license = "MIT"
+keywords = ["bevy"]
+
+[dependencies]
+# bevy
+bevy_transform = { path = "../bevy_transform", version = "0.3.0" }
+bevy_render = { path = "../bevy_render", version = "0.3.0" }
+bevy_window = { path = "../bevy_window", version = "0.3.0" }
+
+# linear algebra
+glam = { version = "0.11.2", features = ["serde"] }
+

crates/bevy_physics/src/d3/geometry.rs

@@ -0,0 +1,55 @@
+use glam::Vec3;
+
+pub struct Plane {
+    center: Vec3,
+    normal: Vec3,
+}
+
+impl Plane {
+    pub fn new(center: Vec3, normal: Vec3) -> Self {
+        normal.normalize();
+        Self { center, normal }
+    }
+
+    pub fn center(&self) -> &Vec3 {
+        &self.center
+    }
+
+    pub fn center_mut(&mut self) -> &mut Vec3 {
+        &mut self.center
+    }
+
+    pub fn normal(&self) -> &Vec3 {
+        &self.normal
+    }
+
+    pub fn set_normal(&mut self, normal: Vec3) {
+        normal.normalize();
+        self.normal = normal;
+    }
+}
+
+impl Default for Plane {
+    fn default() -> Self {
+        Plane {
+            center: Vec3::zero(),
+            normal: Vec3::unit_y(),
+        }
+    }
+}
+
+pub struct Sphere {
+    pub center: Vec3,
+    pub radius: f32,
+}
+
+impl Default for Sphere {
+    fn default() -> Self {
+        Sphere {
+            center: Vec3::zero(),
+            radius: 1.0,
+        }
+    }
+}
+
+pub struct Triangle(pub Vec3, pub Vec3, pub Vec3);

crates/bevy_physics/src/d3/intersectors.rs

@@ -0,0 +1,105 @@
+use super::{geometry::*, ray::*};
+use glam::Vec3;
+
+pub struct RayHit {
+    distance: f32,
+    point: Vec3,
+}
+
+impl RayHit {
+    pub fn new(distance: f32, point: Vec3) -> Self {
+        Self { distance, point }
+    }
+
+    pub fn distance(&self) -> &f32 {
+        &self.distance
+    }
+
+    pub fn point(&self) -> &Vec3 {
+        &self.point
+    }
+}
+
+pub trait RayIntersector {
+    fn intersect_ray(&self, ray: &Ray) -> Option<RayHit>;
+}
+
+impl RayIntersector for Plane {
+    fn intersect_ray(&self, ray: &Ray) -> Option<RayHit> {
+        let denominator = self.normal().dot(*ray.direction());
+        if denominator.abs() > f32::EPSILON {
+            let distance = (*self.center() - *ray.origin()).dot(*self.normal()) / denominator;
+            if distance > 0.0 {
+                return Some(RayHit::new(
+                    distance,
+                    *ray.origin() + *ray.direction() * distance,
+                ));
+            }
+        }
+
+        None
+    }
+}
+
+impl RayIntersector for Sphere {
+    fn intersect_ray(&self, ray: &Ray) -> Option<RayHit> {
+        let oc = *ray.origin() - self.center;
+        let a = ray.direction().length_squared();
+        let b = 2.0 * oc.dot(*ray.direction());
+        let c = oc.length_squared() - self.radius.powi(2);
+
+        let d = b.powi(2) - 4.0 * a * c;
+
+        if d < 0.0 {
+            None
+        } else {
+            let distance = (-b - d.sqrt()) / (2.0 * a);
+
+            Some(RayHit::new(
+                distance,
+                *ray.origin() + *ray.direction() * distance,
+            ))
+        }
+    }
+}
+
+impl RayIntersector for Triangle {
+    // using the Moeller-Trumbore intersection algorithm
+    // Can anyone think of sensible names for theese?
+    #[allow(clippy::many_single_char_names)]
+    fn intersect_ray(&self, ray: &Ray) -> Option<RayHit> {
+        let edges = (self.1 - self.0, self.2 - self.0);
+        let h = ray.direction().cross(edges.1);
+        let a = edges.0.dot(h);
+
+        if a > -f32::EPSILON && a < f32::EPSILON {
+            return None;
+        }
+
+        let f = 1.0 / a;
+        let s = *ray.origin() - self.0;
+        let u = f * s.dot(h);
+
+        if !(0.0..=1.0).contains(&u) {
+            return None;
+        }
+
+        let q = s.cross(edges.0);
+        let v = f * ray.direction().dot(q);
+
+        if v < 0.0 || u + v > 1.0 {
+            return None;
+        }
+
+        let distance = f * edges.1.dot(q);
+
+        if distance > f32::EPSILON {
+            Some(RayHit::new(
+                distance,
+                *ray.origin() + *ray.direction() * distance,
+            ))
+        } else {
+            None
+        }
+    }
+}

crates/bevy_physics/src/d3/mod.rs

@@ -0,0 +1,7 @@
+pub mod geometry;
+pub mod intersectors;
+pub mod ray;
+
+pub mod prelude {
+    pub use super::{geometry::*, intersectors::*, ray::*};
+}

crates/bevy_physics/src/d3/ray.rs

@@ -0,0 +1,73 @@
+use bevy_render::camera::Camera;
+use bevy_transform::components::GlobalTransform;
+use bevy_window::Window;
+use glam::{Vec2, Vec3};
+
+pub struct Ray {
+    origin: Vec3,
+    direction: Vec3,
+}
+
+impl Ray {
+    pub fn new(origin: Vec3, direction: Vec3) -> Self {
+        direction.normalize();
+        Self { origin, direction }
+    }
+
+    pub fn from_window(
+        window: &Window,
+        camera: &Camera,
+        camera_transform: &GlobalTransform,
+    ) -> Self {
+        Self::from_mouse_position(
+            &window.cursor_position().unwrap(),
+            window,
+            camera,
+            camera_transform,
+        )
+    }
+
+    pub fn from_mouse_position(
+        mouse_position: &Vec2,
+        window: &Window,
+        camera: &Camera,
+        camera_transform: &GlobalTransform,
+    ) -> Self {
+        if window.id() != camera.window {
+            panic!("Generating Ray from Camera with wrong Window");
+        }
+
+        let x = 2.0 * (mouse_position.x / window.width() as f32) - 1.0;
+        let y = 2.0 * (mouse_position.y / window.height() as f32) - 1.0;
+
+        let camera_inverse_matrix =
+            camera_transform.compute_matrix() * camera.projection_matrix.inverse();
+        let near = camera_inverse_matrix * Vec3::new(x, y, 0.0).extend(1.0);
+        let far = camera_inverse_matrix * Vec3::new(x, y, 1.0).extend(1.0);
+
+        let near = near.truncate() / near.w;
+        let far = far.truncate() / far.w;
+
+        let direction: Vec3 = far - near;
+        let origin: Vec3 = near;
+
+        Self { origin, direction }
+    }
+
+    pub fn origin(&self) -> &Vec3 {
+        &self.origin
+    }
+
+    pub fn origin_mut(&mut self) -> &mut Vec3 {
+        &mut self.origin
+    }
+
+    pub fn direction(&self) -> &Vec3 {
+        &self.direction
+    }
+
+    pub fn set_direction(&mut self, direction: Vec3) {
+        direction.normalize();
+        self.direction = direction;
+    }
+}

crates/bevy_physics/src/lib.rs

@@ -0,0 +1 @@
+pub mod d3;