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04a-color-matrix.html
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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>WebGL</title>
</head>
<body>
<canvas id="c"></canvas>
<div>
<input type="range" id="brightness" min="-1" max="1" step="0.01" /> Brightness<br />
<input type="range" id="contrast" min="0" max="2" step="0.01" /> Contrast<br />
<input type="range" id="exposure" min="0" max="2" step="0.01" /> Exposure<br />
<input type="range" id="saturation" min="0" max="2" step="0.01" /> Saturation<br />
</div>
<script>
{
const createShader = (gl, type, source) => {
const shader = gl.createShader(type);
gl.shaderSource(shader, source);
gl.compileShader(shader);
const success = gl.getShaderParameter(shader, gl.COMPILE_STATUS);
if (success) {
return shader;
}
console.error(gl.getShaderInfoLog(shader));
gl.deleteShader(shader);
};
const createProgram = (gl, vertexShader, fragmentShader) => {
const program = gl.createProgram();
gl.attachShader(program, vertexShader);
gl.attachShader(program, fragmentShader);
gl.linkProgram(program);
const success = gl.getProgramParameter(program, gl.LINK_STATUS);
if (success) {
return program;
}
console.error(gl.getProgramInfoLog(program));
gl.deleteProgram(program);
};
const canvas = document.querySelector('#c');
const $brightness = document.querySelector('#brightness');
const $contrast = document.querySelector('#contrast');
const $exposure = document.querySelector('#exposure');
const $saturation = document.querySelector('#saturation');
const gl = canvas.getContext('webgl');
const vertexShader = createShader(gl, gl.VERTEX_SHADER, `
precision mediump float;
attribute vec2 a_position;
attribute vec2 a_texCoord;
varying vec2 uv;
void main() {
gl_Position = vec4(a_position, 1, 1);
uv = a_texCoord;
}
`);
const fragmentShader = createShader(gl, gl.FRAGMENT_SHADER, `
precision mediump float;
uniform sampler2D texture;
uniform mat4 u_brightnessMatrix;
uniform vec4 u_brightnessOffset;
uniform mat4 u_contrastMatrix;
uniform vec4 u_contrastOffset;
uniform mat4 u_exposureMatrix;
uniform vec4 u_exposureOffset;
uniform mat4 u_saturationMatrix;
uniform vec4 u_saturationOffset;
varying vec2 uv;
void main() {
vec4 texel = texture2D(texture, uv);
mat4 matrix = u_brightnessMatrix * u_contrastMatrix * u_exposureMatrix * u_saturationMatrix;
vec4 offset = u_brightnessOffset + u_contrastOffset + u_exposureOffset + u_saturationOffset;
gl_FragColor = matrix * texel + offset;
}
`);
const program = createProgram(gl, vertexShader, fragmentShader);
const positionAttributeLocation = gl.getAttribLocation(program, "a_position");
const positionBuffer = gl.createBuffer();
const texCoordAttributeLocation = gl.getAttribLocation(program, "a_texCoord");
const texCoordBuffer = gl.createBuffer();
const u_brightnessMatrixLocation = gl.getUniformLocation(program, "u_brightnessMatrix");
const u_brightnessOffsetLocation = gl.getUniformLocation(program, "u_brightnessOffset");
const u_contrastMatrixLocation = gl.getUniformLocation(program, "u_contrastMatrix");
const u_contrastOffsetLocation = gl.getUniformLocation(program, "u_contrastOffset");
const u_exposureMatrixLocation = gl.getUniformLocation(program, "u_exposureMatrix");
const u_exposureOffsetLocation = gl.getUniformLocation(program, "u_exposureOffset");
const u_saturationMatrixLocation = gl.getUniformLocation(program, "u_saturationMatrix");
const u_saturationOffsetLocation = gl.getUniformLocation(program, "u_saturationOffset");
const u_brightnessMatrix = [
1, 0, 0, 0,
0, 1, 0, 0,
0, 0, 1, 0,
0, 0, 0, 1
];
const u_brightnessOffset = [0, 0, 0, 1];
const u_contrastMatrix = [
1, 0, 0, 0,
0, 1, 0, 0,
0, 0, 1, 0,
0, 0, 0, 1
];
const u_contrastOffset = [0, 0, 0, 1];
const u_exposureMatrix = [
1, 0, 0, 0,
0, 1, 0, 0,
0, 0, 1, 0,
0, 0, 0, 1
];
const u_exposureOffset = [0, 0, 0, 1];
const u_saturationMatrix = [
1, 0, 0, 0,
0, 1, 0, 0,
0, 0, 1, 0,
0, 0, 0, 1
];
const u_saturationOffset = [0, 0, 0, 1];
const init = async () => {
const imgTexture = await loadImage("images/devine_selectie-087.jpg");
gl.useProgram(program);
gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
gl.bufferData(
gl.ARRAY_BUFFER,
new Float32Array([
-1.0, 1.0,
1.0, 1.0,
-1.0, -1.0,
-1.0, -1.0,
1.0, 1.0,
1.0, -1.0
]),
gl.STATIC_DRAW);
gl.enableVertexAttribArray(positionAttributeLocation);
gl.vertexAttribPointer(positionAttributeLocation, 2, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ARRAY_BUFFER, texCoordBuffer);
gl.bufferData(
gl.ARRAY_BUFFER,
new Float32Array([
0.0, 0.0,
1.0, 0.0,
0.0, 1.0,
0.0, 1.0,
1.0, 0.0,
1.0, 1.0,
]),
gl.STATIC_DRAW);
gl.enableVertexAttribArray(texCoordAttributeLocation);
gl.vertexAttribPointer(texCoordAttributeLocation, 2, gl.FLOAT, false, 0, 0);
uploadImageToTexture(imgTexture, "texture", 0);
canvas.width = imgTexture.width;
canvas.height = imgTexture.height;
$brightness.addEventListener('input', (e) => {
const y = parseFloat(e.target.value);
u_brightnessOffset[0] = y;
u_brightnessOffset[1] = y;
u_brightnessOffset[2] = y;
});
$contrast.addEventListener('input', (e) => {
const value = parseFloat(e.target.value);
const y = (1 - value) / 2
u_contrastMatrix[0] = value;
u_contrastMatrix[5] = value;
u_contrastMatrix[10] = value;
u_contrastOffset[0] = y;
u_contrastOffset[1] = y;
u_contrastOffset[2] = y;
});
$exposure.addEventListener('input', (e) => {
const value = parseFloat(e.target.value);
u_exposureMatrix[0] = value;
u_exposureMatrix[5] = value;
u_exposureMatrix[10] = value;
});
$saturation.addEventListener('input', (e) => {
const s = parseFloat(e.target.value);
// https://www.w3.org/TR/WCAG20/#relativeluminancedef
const lr = 0.2126;
const lg = 0.7152;
const lb = 0.0722;
const sr = (1 - s) * lr;
const sg = (1 - s) * lg;
const sb = (1 - s) * lb;
transpose(u_saturationMatrix, [
sr + s, sg , sb , 0,
sr , sg + s, sb , 0,
sr , sg , sb + s, 0,
0 , 0 , 0 , 1,
]);
});
drawScene();
};
const map = (value, x1, y1, x2, y2) => (value - x1) * (y2 - x2) / (y1 - x1) + x2;
const transpose = (out, a) => {
// If we are transposing ourselves we can skip a few steps but have to cache some values
if (out === a) {
let a01 = a[1],
a02 = a[2],
a03 = a[3];
let a12 = a[6],
a13 = a[7];
let a23 = a[11];
out[1] = a[4];
out[2] = a[8];
out[3] = a[12];
out[4] = a01;
out[6] = a[9];
out[7] = a[13];
out[8] = a02;
out[9] = a12;
out[11] = a[14];
out[12] = a03;
out[13] = a13;
out[14] = a23;
} else {
out[0] = a[0];
out[1] = a[4];
out[2] = a[8];
out[3] = a[12];
out[4] = a[1];
out[5] = a[5];
out[6] = a[9];
out[7] = a[13];
out[8] = a[2];
out[9] = a[6];
out[10] = a[10];
out[11] = a[14];
out[12] = a[3];
out[13] = a[7];
out[14] = a[11];
out[15] = a[15];
}
return out;
}
const drawScene = () => {
gl.viewport(0, 0, gl.canvas.width, gl.canvas.height);
gl.clearColor(0, 0, 0, 0);
gl.clear(gl.COLOR_BUFFER_BIT);
gl.useProgram(program);
gl.uniformMatrix4fv(u_brightnessMatrixLocation, false, u_brightnessMatrix);
gl.uniform4fv(u_brightnessOffsetLocation, u_brightnessOffset);
gl.uniformMatrix4fv(u_contrastMatrixLocation, false, u_contrastMatrix);
gl.uniform4fv(u_contrastOffsetLocation, u_contrastOffset);
gl.uniformMatrix4fv(u_exposureMatrixLocation, false, u_exposureMatrix);
gl.uniform4fv(u_exposureOffsetLocation, u_exposureOffset);
gl.uniformMatrix4fv(u_saturationMatrixLocation, false, u_saturationMatrix);
gl.uniform4fv(u_saturationOffsetLocation, u_saturationOffset);
gl.drawArrays(gl.TRIANGLES, 0, 6);
requestAnimationFrame(drawScene);
};
const loadImage = (src) => {
return new Promise((resolve, reject) => {
const img = new Image();
img.addEventListener("load", () => resolve(img));
img.addEventListener("error", err => reject(err));
img.src = src;
});
};
const uploadImageToTexture = (img, uniformName, textureUnitIndex) => {
const u_imageLoc = gl.getUniformLocation(program, uniformName);
gl.uniform1i(u_imageLoc, textureUnitIndex);
const texture = gl.createTexture();
gl.activeTexture(gl.TEXTURE0 + textureUnitIndex);
gl.bindTexture(gl.TEXTURE_2D, texture);
// Set the parameters so we can render any size image.
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.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
// Upload the image into the texture.
gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, img);
};
init();
}
</script>
</body>
</html>