Add 4-octave fractal noise implementation to noiseGLSL.glsl

src/webgl/shaders/functions/noiseGLSL.glsl

@@ -7,23 +7,34 @@ vec2 random2(vec2 st) {
   return -1.0 + 2.0 * fract(sin(st) * 43758.5453123);
 }
 
-float noise(vec2 st) {
+float baseNoise(vec2 st) {
   vec2 i = floor(st);
   vec2 f = fract(st);
 
-  // Four corners in 2D of a tile
   vec2 a = random2(i);
   vec2 b = random2(i + vec2(1.0, 0.0));
   vec2 c = random2(i + vec2(0.0, 1.0));
   vec2 d = random2(i + vec2(1.0, 1.0));
 
-  // Smooth interpolation
   vec2 u = f * f * (3.0 - 2.0 * f);
 
-  // Mix the results
   return mix(mix(dot(a, f - vec2(0.0, 0.0)), 
                  dot(b, f - vec2(1.0, 0.0)), u.x),
              mix(dot(c, f - vec2(0.0, 1.0)), 
                  dot(d, f - vec2(1.0, 1.0)), u.x), u.y);
 }
 
+// Fractal noise using 4 octaves
+float noise(vec2 st) {
+  float result = 0.0;
+  float amplitude = 1.0;
+  float frequency = 1.0;
+
+  for (int i = 0; i < 4; i++) {
+    result += amplitude * baseNoise(st * frequency);
+    frequency *= 2.0;
+    amplitude *= 0.5;
+  }
+
+  return result;
+}