Snippet Zone

GLSL Sierpiński Glitch Texture #3

```
const vert = `#version 300 es
```
```
layout(location = 0) in vec3 position;
```
```
out vec2 uv;
```
```
void main(void) {
```
```
  uv = position.xy * 0.5 + 0.5;
```
```
  gl_Position = vec4(position, 1.0);
```
```
}
```
```
`;
```
```
 
```
```
const frag1 = `#version 300 es
```
```
precision highp float;
```
```
uniform float time;
```
```
uniform float dx;
```
```
uniform float dy;
```
```
 
```

float w2 = 1.0 / float(${innerWidth * 2});

float w10 = 1.0 / (float(${innerWidth * 2}) * 100.);

```
float convert = 3.141592653589 / 180.;
```
```
 
```
```
float sn;
```
```
float cs;
```
```
 
```
```
out vec4 fragColor;
```
```
 
```
```
void main(void) {
```

  vec2 uv = gl_FragCoord.xy / vec2(float(${innerWidth * 2}), float(${innerHeight * 2}));

```
 
```

  float xp = uv.x * float(${innerWidth * 2});

  float yp = (1. - uv.y) * float(${innerHeight * 2});

```
  int x = 10 | 2;
```
```
  int xp2 = int(xp) << 1; 
```

  float t = mod(float(int(yp) | int(xp + yp * .1) ) * (xp + dx) * (w10), 6.283185307179586);

```
 
```
```
  if (t < 0.) {
```

    sn = 1.27323954 * t + .405284735 * t * t;

```
  } else {
```

    sn = 1.27323954 * t - 0.405284735 * t * t;

```
  }
```
```
 
```

  t = mod(float( (xp2 | int(yp + xp * .1 + dy) )) * convert, 6.283185307179586);

```
 
```
```
  t += 1.57079632;
```
```
  if (t > 3.14159265) {
```
```
    t -= 6.28318531;
```
```
  }
```
```
  if (t < 0.) {
```

    cs = 1.27323954 * t + 0.405284735 * t * t;

```
  } else {
```

    cs = 1.27323954 * t - 0.405284735 * t * t;

```
  }
```
```
 
```
```
  float c1 = 30. * (sn - cs);
```
```
 
```
```
  if (c1 < 0.) c1 = 255. - c1;
```

  c1 = float((int(c1) << 4 | int(c1)) & 255) / 255.;

```
 
```
```
  fragColor = vec4(c1, c1, c1, 1.0);
```
```
} 
```
```
`;
```
```
 
```
```
const frag2 = `#version 300 es
```
```
precision highp float;
```
```
in vec2 uv;
```
```
 
```

  // The max kernel size (impacts performance)

```
#define maxKernel 1.0
```
```
 
```

// The max offset (doesn't impact performance)

```
#define maxOffset 34.0
```
```
uniform sampler2D uTexture; 
```
```
 
```
```
 
```

// https://www.shadertoy.com/view/mdGcRh

vec3 fastBlur(vec2 uv, vec2 texel, vec2 kd)

```
{
```
```
float r = kd.x * kd.y;
```
```
float rr = 1.0/r;
```
```
vec3 col = vec3(0.0);
```
```
float a = 1.0;
```
```
 
```

for (float x = -r; x <= r; x += kd.y) {

for (float y = -r; y <= r; y += kd.y)  {

```
a++;
```
```
vec2 c = uv + vec2(x,y) * texel;
```

col += texture(uTexture, c + fract(sin(dot(c, vec2(12.9898, 78.233))) * 43758.5453) * texel * kd.y * 2.0 - kd.yy * texel).rgb * (2.0 - distance(vec2(x,y) * rr, vec2(0.0)));

```
}
```
```
}
```
```
 
```
```
return col / a;
```
```
}
```
```
 
```
```
 
```
```
out vec4 fragColor;
```
```
void main(void) {
```
```
  vec4 color = texture(uTexture, uv);
```

  vec4 colorB = texture(uTexture, vec2(uv.x, 1. - uv.y));

  vec3 result = (color.rgb - colorB.rgb) * 1.2;

```
 
```
```
    float amt = .4;
```

    vec2 texel = vec2(1.0)/ vec2(float(${innerWidth * 2}), float(${innerHeight * 2}));

```
 
```

    vec2 kd = round(vec2(amt * maxKernel + 1.0, amt * maxOffset + 1.0));

```
 
```

    vec3 blur = fastBlur(uv, texel, kd);

```
 
```
```
  fragColor = vec4(result, color.a);
```
```
}
```
```
`;
```
```
 
```
```
  const frag3 = `#version 300 es
```
```
precision highp float;
```
```
in vec2 uv;
```
```
 
```

  // The max kernel size (impacts performance)

```
#define maxKernel 4.0
```
```
 
```

// The max offset (doesn't impact performance)

```
#define maxOffset 34.0
```
```
uniform sampler2D uTexture; 
```
```
 
```
```
 
```

// https://www.shadertoy.com/view/mdGcRh

vec3 fastBlur(vec2 uv, vec2 texel, vec2 kd)

```
{
```
```
float r = kd.x * kd.y;
```
```
float rr = 1.0/r;
```
```
vec3 col = vec3(0.0);
```
```
float a = 1.0;
```
```
 
```

for (float x = -r; x <= r; x += kd.y) {

for (float y = -r; y <= r; y += kd.y)  {

```
a++;
```
```
      vec2 c = uv + vec2(x,y) * texel;
```
```
 
```
```
      col += texture(
```
```
 
```
```
      uTexture, 
```
```
 
```
```
      c 
```

      + fract(sin(dot(c, vec2(2.9898, 78.233))) * 13758.5453) * texel * kd.y * 2.4

```
      - kd.yy * texel
```
```
 
```

      ).rgb * (2.0 - distance(vec2(x,y) * rr, vec2(0.0)));

```
}
```
```
}
```
```
 
```
```
return col / a;
```
```
}
```
```
 
```
```
 
```
```
out vec4 fragColor;
```
```
void main(void) {
```
```
  vec4 color = texture(uTexture, uv);
```
```
 
```
```
    float amt = .4;
```

    vec2 texel = vec2(1.0)/ vec2(float(${innerWidth * 2}), float(${innerHeight * 2}));

```
 
```

    vec2 kd = round(vec2(amt * maxKernel + 1.0, amt * maxOffset + 1.0));

```
 
```

  vec4 blur = vec4(fastBlur(uv, texel, kd), 1.);

```
    //1-(1-A)*(1-B)
```

  vec3 f = 1. - (1. - color.rgb) * (1. - blur.rgb);

```
 
```
```
 
```
```
  fragColor = vec4(f.rgb, 1.);
```
```
} 
```
```
`;
```
```
 
```
```
 
```
```
 
```

document.body.style.background = '#000';

```
const gl = document.body
```

  .appendChild(document.createElement('canvas'))

```
  .getContext('webgl2');
```
```
 
```
```
Object.assign(gl.canvas.style, {
```
```
  position: 'absolute',
```
```
  left: 0,
```
```
  top: 0
```
```
});
```
```
 
```
```
const s = 1;
```
```
const verts = new Float32Array([
```
```
  -s, -s, 0,
```
```
  s, -s, 0,
```
```
  -s, s, 0,
```
```
  s, s, 0,
```
```
]);
```
```
 
```
```
const buffer = gl.createBuffer();
```
```
gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
```

gl.bufferData(gl.ARRAY_BUFFER, verts, gl.STATIC_DRAW);

```
 
```

function createShaderProgram(vertexSource, fragmentSource) {

  const vs = gl.createShader(gl.VERTEX_SHADER);

```
  gl.shaderSource(vs, vertexSource);
```
```
  gl.compileShader(vs);
```
```
 
```

  const fs = gl.createShader(gl.FRAGMENT_SHADER);

```
  gl.shaderSource(fs, fragmentSource);
```
```
  gl.compileShader(fs);
```
```
 
```
```
  const program = gl.createProgram();
```
```
  gl.attachShader(program, vs);
```
```
  gl.attachShader(program, fs);
```
```
  gl.linkProgram(program);
```
```
 
```

  if (!gl.getProgramParameter(program, gl.LINK_STATUS)) {

    console.error('Could not link program:', gl.getProgramInfoLog(program));

```
  }
```
```
 
```
```
  return program;
```
```
}
```
```
 
```

const program1 = createShaderProgram(vert, frag1);

const program2 = createShaderProgram(vert, frag2);

const program3 = createShaderProgram(vert, frag3);

```
 
```

const framebuffer1 = gl.createFramebuffer();

const framebuffer2 = gl.createFramebuffer();

```
const texture1 = gl.createTexture();
```
```
const texture2 = gl.createTexture();
```
```
 
```

gl.bindTexture(gl.TEXTURE_2D, texture1);

gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, innerWidth, innerHeight, 0, gl.RGBA, gl.UNSIGNED_BYTE, null);

gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);

gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);

gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);

```
 
```

gl.bindTexture(gl.TEXTURE_2D, texture2);

gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, innerWidth, innerHeight, 0, gl.RGBA, gl.UNSIGNED_BYTE, null);

gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);

gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);

gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);

```
 
```

gl.bindFramebuffer(gl.FRAMEBUFFER, framebuffer1);

gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, texture1, 0);

```
 
```

gl.bindFramebuffer(gl.FRAMEBUFFER, framebuffer2);

gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, texture2, 0);

```
 
```
```
const onResize = () => {
```
```
  gl.canvas.width = innerWidth * 2;
```
```
  gl.canvas.height = innerHeight * 2;
```

  gl.canvas.style.width = innerWidth + 'px'

  gl.canvas.style.height = innerHeight + 'px'

  gl.viewport(0, 0, innerWidth * 2, innerHeight * 2);

  gl.bindTexture(gl.TEXTURE_2D, texture1);

  gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, innerWidth * 2, innerHeight * 2, 0, gl.RGBA, gl.UNSIGNED_BYTE, null);

  gl.bindTexture(gl.TEXTURE_2D, texture2);

  gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, innerWidth * 2, innerHeight * 2, 0, gl.RGBA, gl.UNSIGNED_BYTE, null);

```
};
```
```
 
```
```
window.onresize = onResize;
```
```
onResize();
```
```
 
```
```
gl.disable(gl.DEPTH_TEST);
```
```
 
```
```
let mx = 0;
```
```
let my = 0;
```
```
let dx = 0;
```
```
let dy = 0;
```
```
 
```
```
window.onpointermove = e => {
```
```
  mx = e.clientX;
```
```
  my = e.clientY;
```
```
};
```
```
 
```
```
const loop = () => {
```
```
 
```

  dx += (mx * 2 - (innerWidth) - dx) / 8;

```
  dy += (my * 2 - dy) / 8;
```
```
 
```
```
  // first pass
```

  gl.bindFramebuffer(gl.FRAMEBUFFER, framebuffer1);

```
  gl.useProgram(program1);
```
```
 
```

  const mxUniform = gl.getUniformLocation(program1, 'dx');

```
  gl.uniform1f(mxUniform, dx);
```
```
 
```

  const myUniform = gl.getUniformLocation(program1, 'dy');

```
  gl.uniform1f(myUniform, dy);
```
```
 
```

  gl.bindBuffer(gl.ARRAY_BUFFER, buffer);

  const pos1 = gl.getAttribLocation(program1, 'position');

```
  gl.enableVertexAttribArray(pos1);
```

  gl.vertexAttribPointer(pos1, 3, gl.FLOAT, false, 0, 0);

```
  gl.clearColor(0, 0, 0, 1);
```
```
  gl.clear(gl.COLOR_BUFFER_BIT);
```

  gl.drawArrays(gl.TRIANGLE_STRIP, 0, 4);

```
 
```
```
  // second pass
```

  gl.bindFramebuffer(gl.FRAMEBUFFER, framebuffer2);

```
  gl.useProgram(program2);
```

  gl.bindBuffer(gl.ARRAY_BUFFER, buffer);

  const pos2 = gl.getAttribLocation(program2, 'position');

```
  gl.enableVertexAttribArray(pos2);
```

  gl.vertexAttribPointer(pos2, 3, gl.FLOAT, false, 0, 0);

  const uTexture = gl.getUniformLocation(program2, 'uTexture');

```
  gl.uniform1i(uTexture, 0);
```
```
  gl.activeTexture(gl.TEXTURE0);
```

  gl.bindTexture(gl.TEXTURE_2D, texture1);

```
  gl.clearColor(0, 0, 0, 1);
```
```
  gl.clear(gl.COLOR_BUFFER_BIT);
```

  gl.drawArrays(gl.TRIANGLE_STRIP, 0, 4);

```
 
```
```
  // third pass
```

  gl.bindFramebuffer(gl.FRAMEBUFFER, null);

```
  gl.useProgram(program3);
```

  gl.bindBuffer(gl.ARRAY_BUFFER, buffer);

  const pos3 = gl.getAttribLocation(program3, 'position');

```
  gl.enableVertexAttribArray(pos3);
```

  gl.vertexAttribPointer(pos3, 3, gl.FLOAT, false, 0, 0);

  const u2Texture = gl.getUniformLocation(program3, 'uTexture');

```
  gl.uniform1i(u2Texture, 0);
```
```
  gl.activeTexture(gl.TEXTURE0);
```

  gl.bindTexture(gl.TEXTURE_2D, texture2);

```
  gl.clearColor(0, 0, 0, 1);
```
```
  gl.clear(gl.COLOR_BUFFER_BIT);
```

  gl.drawArrays(gl.TRIANGLE_STRIP, 0, 4);

```
 
```
```
  requestAnimationFrame(loop);
```
```
};
```
```
loop();
```

this old thing was tricky to port to glsl, canvas port was easy (codepen here) – used gpt a bit for glsl version… got it eventually: take a look

February 16, 2025

// binary // color // filters // glsl // graphics // hacks // hex // javascript // math // webgl

GLSL Sierpiński Glitch Texture #3

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