Layered noise

src/bin/envmap/main.rs

@@ -37,8 +37,9 @@ fn main() {
 		&queue,
 		perlin::Params {
 			seed: 42,
-			layers: 4,
-			persistence: 0.5,
+			layers: 8,
+			roughness: 0.9,
+			scale: 1.7,
 		},
 	);
 

src/bin/envmap/perlin.rs

@@ -8,7 +8,8 @@ use glam::{Vec2, Vec3};
 pub struct Params {
 	pub seed: u32,
 	pub layers: u32,
-	pub persistence: f32,
+	pub roughness: f32,
+	pub scale: f32,
 }
 
 #[derive(Debug, Clone, Copy, Pod, Zeroable)]

src/bin/envmap/perlin.wgsl

@@ -1,7 +1,8 @@
 struct Params {
 	seed: u32,
 	layers: u32,
-	persistence: f32,
+	roughness: f32,
+	scale: f32,
 }
 
 struct Vertex {
@@ -23,16 +24,26 @@ fn on_vertex(in: Vertex) -> Varying {
 
 @fragment
 fn on_fragment(in: Varying) -> @location(0) vec4f {
-	return vec4(0.5 + 0.5 * noise(in.world));
+	var result = 0.0;
+	var hscale = 1.0;
+	var vscale = 1.0;
+	var seed = params.seed;
+	for (var layer = 0u; layer < params.layers; layer++) {
+		result += vscale * noise(seed, hscale * in.world);
+		hscale *= params.scale;
+		vscale *= params.roughness;
+		seed = hash(seed);
+	}
+	return vec4(0.5 + 0.25 * result);
 }
 
-fn noise(coords: vec3f) -> f32 {
+fn noise(seed: u32, coords: vec3f) -> f32 {
 	let s = split(coords);
 	var ret = 0.0;
 	for (var i = 0u; i < 2; i++) {
 		for (var j = 0u; j < 2; j++) {
 			for (var k = 0u; k < 2; k++) {
-				ret += part(params.seed, s, vec3u(i, j, k));
+				ret += part(seed, s, vec3u(i, j, k));
 			}
 		}
 	}