Add glare

src/bin/minitracer/main.rs

@@ -143,9 +143,10 @@ fn main() {
 						for _ in 0..RAYS_PER_PIXEL {
 							frame += 1;
 							let time = frame as f32 / (60. * RAYS_PER_PIXEL as f32);
+							let target = sphere_params[0].to_sphere(time - 0.2).center;
 							let eye = camera_params.to_sphere(time).center;
 							let right = camera_params.deriv(time);
-							let forward = target_params.to_sphere(time).center - eye;
+							let forward = target - eye;
 							let viewport = make_viewport(size.width, size.height);
 							let location = convert_location(CamLoc { eye, forward, right });
 							let spheres: Vec<_> = sphere_params.iter().map(|p| p.to_sphere(time)).collect();
@@ -163,7 +164,9 @@ fn main() {
 								viewport,
 								trace::Aperture {
 									radius: 0.001,
-									focal_distance: std::f32::INFINITY,
+									focal_distance: forward.length(),
+									glare_strength: 0.1,
+									glare_radius: 0.1,
 								},
 								location,
 							);

src/bin/minitracer/trace.rs

@@ -18,9 +18,12 @@ pub struct Viewport {
 	pub corner: Vec3,
 }
 
+#[derive(Debug, Clone, Copy)]
 pub struct Aperture {
 	pub radius: f32,
 	pub focal_distance: f32, // from 0 (exclusive) to +∞ (inclusive)
+	pub glare_strength: f32,
+	pub glare_radius: f32, // at distance 1
 }
 
 #[derive(Debug, Clone, Copy)]
@@ -47,6 +50,8 @@ struct CameraData {
 	aperture: f32,
 	eye: Vec3,
 	antifocal: f32,
+	glare_strength: f32,
+	glare_radius: f32,
 }
 
 impl From<(Viewport, CameraLocation, Aperture)> for CameraData {
@@ -60,6 +65,8 @@ impl From<(Viewport, CameraLocation, Aperture)> for CameraData {
 			height: value.0.corner.y / value.0.corner.z,
 			aperture: value.2.radius,
 			antifocal: 1. / value.2.focal_distance,
+			glare_strength: value.2.glare_strength,
+			glare_radius: value.2.glare_radius,
 		}
 	}
 }

src/bin/minitracer/trace.wgsl

@@ -12,6 +12,9 @@ struct Params {
 	aperture: f32,
 	eye: vec3f,
 	antifocal: f32,
+
+	glare_strength: f32,
+	glare_radius: f32,
 }
 
 struct Sphere {
@@ -81,7 +84,13 @@ fn trace_fragment(in: Varying) -> vec3f {
 	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));
-	let dir = in.dir + off_w * off_px;
+	var dir = in.dir + off_w * off_px;
+	if (rand_float() < params.glare_strength) {
+		let p = rand_float();
+		let d = params.glare_radius * pow(p, 3.);
+		let glare_off = d * rand_disc();
+		dir += view_mtx * vec3(glare_off, 0.);
+	}
 	ray = normalize(dir - params.antifocal * aperture_offset_abs);
 
 	for (var k = 0; k < params.max_reflections; k++) {