Playing around with better random values in GPU.js

math-random-uniformly-distributed.js

// language=GLSL
const source = `// https://www.shadertoy.com/view/4t2SDh
//note: uniformly distributed, normalized rand, [0,1]
highp float randomSeedShift = 0.0;
highp float previousRandomSeedShift = 0.0;
bool flip = false;
const highp float factor = 9999.0;
uniform highp float randomSeed1;
uniform highp float randomSeed2;
highp float nrand(highp vec2 n) {
  previousRandomSeedShift = randomSeedShift;
  if (previousRandomSeedShift > 0.0) {
    if (flip) {
      flip = false;
      return randomSeedShift = fract(sin(dot(n.xy * vec2(randomSeedShift * factor, previousRandomSeedShift * factor), vec2(12.9898, 78.233))) * 43758.5453);
    }
    flip = true;
    return randomSeedShift = fract(sin(dot(n.xy * vec2(previousRandomSeedShift * factor, randomSeedShift * factor), vec2(12.9898, 78.233))) * 43758.5453);
  }
  if (randomSeedShift > 0.0) {
    return randomSeedShift = fract(sin(dot(n.xy * vec2(randomSeed1 * factor, randomSeedShift * factor), vec2(12.9898, 78.233))) * 43758.5453);  
  }
  return randomSeedShift = fract(sin(dot(n.xy * vec2(randomSeed1 * factor, randomSeed2 * factor), vec2(12.9898, 78.233))) * 43758.5453);
}`;

const name = 'math-random-uniformly-distributed';

// language=JavaScript
const functionMatch = `Math.random()`;

const functionReplace = `nrand(vTexCoord)`;

const functionReturnType = 'Number';
/**
 *
 * @param {Kernel} kernel
 */
const onBeforeRun = (kernel) => {
  kernel.setUniform1f('randomSeed1', Math.random());
  kernel.setUniform1f('randomSeed2', Math.random());
};

/**
 *
 * @type IPlugin
 */
module.exports = {
  name,
  onBeforeRun,
  functionMatch,
  functionReplace,
  functionReturnType,
  source
};