Merge pull request #7921 from LalitNarayanYadav/patch-8

Add GLSL-based noise(vec2) function to p5.strands (#7897)

Author: perminder-17

src/webgl/ShaderGenerator.js

@@ -7,6 +7,7 @@
 import { parse } from 'acorn';
 import { ancestor } from 'acorn-walk';
 import escodegen from 'escodegen';
+import noiseGLSL from './shaders/functions/noiseGLSL.glsl';
 
 function shadergenerator(p5, fn) {
 
@@ -1578,6 +1579,7 @@ function shadergenerator(p5, fn) {
     ],
     'sqrt': { args: ['genType'], returnType: 'genType', isp5Function: true},
     'step': { args: ['genType', 'genType'], returnType: 'genType', isp5Function: false},
+    'noise': { args: ['vec2'], returnType: 'float', isp5Function: false },
     'trunc': { args: ['genType'], returnType: 'genType', isp5Function: false},
 
     ////////// Vector //////////
@@ -1629,10 +1631,19 @@ function shadergenerator(p5, fn) {
       return originalLerp.apply(this, args); // Fallback to normal p5.js lerp
     }
   };
+  const originalNoise = fn.noise;
+  fn.noise = function (...args) {
+    if (!GLOBAL_SHADER?.isGenerating) {
+      return originalNoise.apply(this, args); // fallback to regular p5.js noise
+    }
+    
+    GLOBAL_SHADER.output.vertexDeclarations.add(noiseGLSL);
+    GLOBAL_SHADER.output.fragmentDeclarations.add(noiseGLSL);
+    return fnNodeConstructor('noise', args, { args: ['vec2'], returnType: 'float' });
+  };
 }
 
 
-
 export default shadergenerator;
 
 if (typeof p5 !== 'undefined') {

src/webgl/shaders/functions/noiseGLSL.glsl

@@ -0,0 +1,29 @@
+// Based on https://github.com/patriciogonzalezvivo/lygia/blob/main/generative/noise.glsl (MIT)
+// Adapted for use in p5.strands
+
+vec2 random2(vec2 st) {
+  st = vec2(dot(st, vec2(127.1, 311.7)),
+            dot(st, vec2(269.5, 183.3)));
+  return -1.0 + 2.0 * fract(sin(st) * 43758.5453123);
+}
+
+float noise(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);
+}
+