uv test fix: no polar uv, fbm replacement

packages/shaders/src/shaders/smoke-ring.ts

@@ -35,23 +35,47 @@ export const smokeRingFragmentShader = `
     #define TWO_PI 6.28318530718
     #define PI 3.14159265358979323846
 
-    float rand(vec2 n) {
-        return fract(cos(dot(n, vec2(12.9898, 4.1414))) * 43758.5453);
-    }
-    float noise(vec2 n) {
-        const vec2 d = vec2(0.0, 1.0);
-        vec2 b = floor(n), f = smoothstep(vec2(0.0), vec2(1.0), fract(n));
-        return mix(mix(rand(b), rand(b + d.yx), f.x), mix(rand(b + d.xy), rand(b + d.yy), f.x), f.y);
-    }
-    float fbm(vec2 n) {
-        float total = 0.0, amplitude = .4;
-        for (int i = 0; i < 12; i++) {
-            total += noise(n) * amplitude;
-            n *= 1.8;
-            amplitude *= 0.6;
-        }
-        return total;
-    }
+  float random (in vec2 st) {
+      return fract(sin(dot(st.xy,
+                           vec2(12.9898,78.233)))*
+          43758.5453123);
+  }
+  
+  // Based on Morgan McGuire @morgan3d
+  // https://www.shadertoy.com/view/4dS3Wd
+  float noise (in vec2 st) {
+      vec2 i = floor(st);
+      vec2 f = fract(st);
+  
+      // Four corners in 2D of a tile
+      float a = random(i);
+      float b = random(i + vec2(1.0, 0.0));
+      float c = random(i + vec2(0.0, 1.0));
+      float d = random(i + vec2(1.0, 1.0));
+  
+      vec2 u = f * f * (3.0 - 2.0 * f);
+  
+      return mix(a, b, u.x) +
+              (c - a)* u.y * (1.0 - u.x) +
+              (d - b) * u.x * u.y;
+  }
+  
+  #define OCTAVES 10
+  float fbm (in vec2 st) {
+      // Initial values
+      float value = 0.0;
+      float amplitude = .5;
+      float frequency = 0.;
+      //
+      // Loop of octaves
+      for (int i = 0; i < OCTAVES; i++) {
+          value += amplitude * noise(st);
+          st *= 2.;
+          amplitude *= .5;
+      }
+      return value;
+  }
+
 
     void main() {
 
@@ -65,6 +89,6 @@ export const smokeRingFragmentShader = `
         float noise_left = fbm(uv + vec2(0., t));
 
                 
-        gl_FragColor = vec4(vec3(noise_left, noise_left, 0.), 1.);
+        gl_FragColor = vec4(vec3(noise_left, 0., 0.), 1.);
     }
 `;