Add non-zero aperture

src/bin/minitracer/main.rs

@@ -161,6 +161,10 @@ fn main() {
 									seed: frame,
 								},
 								viewport,
+								trace::Aperture {
+									radius: 0.001,
+									focal_distance: std::f32::INFINITY,
+								},
 								location,
 							);
 						}

src/bin/minitracer/trace.rs

@@ -18,6 +18,11 @@ pub struct Viewport {
 	pub corner: Vec3,
 }
 
+pub struct Aperture {
+	pub radius: f32,
+	pub focal_distance: f32, // from 0 (exclusive) to +∞ (inclusive)
+}
+
 #[derive(Debug, Clone, Copy)]
 pub struct CameraLocation {
 	pub eye: Vec3,
@@ -39,13 +44,13 @@ struct CameraData {
 	v: Vec3,
 	height: f32,
 	w: Vec3,
-	pad3: f32,
+	aperture: f32,
 	eye: Vec3,
-	pad4: f32,
+	antifocal: f32,
 }
 
-impl From<(Viewport, CameraLocation)> for CameraData {
+impl From<(Viewport, CameraLocation, Aperture)> for CameraData {
-	fn from(value: (Viewport, CameraLocation)) -> Self {
+	fn from(value: (Viewport, CameraLocation, Aperture)) -> Self {
 		CameraData {
 			u: value.1.view.x_axis,
 			v: value.1.view.y_axis,
@@ -53,8 +58,8 @@ impl From<(Viewport, CameraLocation)> for CameraData {
 			eye: value.1.eye,
 			width: value.0.corner.x / value.0.corner.z,
 			height: value.0.corner.y / value.0.corner.z,
-			pad3: 0.,
+			aperture: value.2.radius,
-			pad4: 0.,
+			antifocal: 1. / value.2.focal_distance,
 		}
 	}
 }
@@ -228,6 +233,7 @@ impl Tracer {
 		env: &TracerEnv,
 		params: Params,
 		viewport: Viewport,
+		aperture: Aperture,
 		camera: CameraLocation,
 	) {
 		pass.set_pipeline(&self.pipeline);
@@ -236,7 +242,7 @@ impl Tracer {
 			0,
 			bytes_of(&ParamsData {
 				params,
-				camera: (viewport, camera).into(),
+				camera: (viewport, camera, aperture).into(),
 			}),
 		);
 		pass.set_vertex_buffer(0, self.view_buf.slice(..));

src/bin/minitracer/trace.wgsl

@@ -9,7 +9,9 @@ struct Params {
 	up: vec3f,
 	height: f32,
 	forward: vec3f,
+	aperture: f32,
 	eye: vec3f,
+	antifocal: f32,
 }
 
 struct Sphere {
@@ -73,10 +75,14 @@ fn trace_fragment(in: Varying) -> vec3f {
 
 	var result = vec3(0.);
 	var color = vec3(1.);
-	pos = params.eye;
+	let view_mtx = mat3x3(params.right, params.up, params.forward);
+	let aperture_offset_rel = params.aperture * rand_disc();
+	let aperture_offset_abs = view_mtx * vec3(aperture_offset_rel, 0.);
+	pos = params.eye + aperture_offset_abs;
 	let off_px = vec2(rand_float(), rand_float()) - .5;
 	let off_w = mat2x3(dpdx(in.dir), dpdy(in.dir));
-	ray = normalize(in.dir + off_w * off_px);
+	let dir = in.dir + off_w * off_px;
+	ray = normalize(dir - params.antifocal * aperture_offset_abs);
 
 	for (var k = 0; k < params.max_reflections; k++) {
 		var sphere = -1;
@@ -140,6 +146,16 @@ fn rand_float() -> f32 {
 	return f32(rand_next()) / 0x1p32;
 }
 
+fn rand_disc() -> vec2f {
+	for (var k = 0; k < 16; k++) {
+		let v = vec2f(rand_float(), rand_float()) - 0.5;
+		if (length(v) <= 0.5) {
+			return 2. * v;
+		}
+	}
+	return vec2f(0.0); // safeguard
+}
+
 fn rand_sphere() -> vec3f {
 	for (var k = 0; k < 16; k++) {
 		let v = vec3f(rand_float(), rand_float(), rand_float()) - 0.5;