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webglnoise.html
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webglnoise.html
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<!DOCTYPE html>
<!--check for more details about centroid: https://www.opengl.org/pipeline/article/vol003_6/-->
<html lang="en">
<head>
<title>WebGL 2 Noise</title>
<meta charset="utf-8">
</head>
<body style="margin: 0; overflow: hidden;"><canvas id="canvas"></canvas>
<!--
for most samples webgl-utils only provides shader compiling/linking and
canvas resizing because why clutter the examples with code that's the same in every sample.
See https://webglfundamentals.org/webgl/lessons/webgl-boilerplate.html
and https://webglfundamentals.org/webgl/lessons/webgl-resizing-the-canvas.html
for webgl-utils, m3, m4, and webgl-lessons-ui.
-->
<script src="https://webgl2fundamentals.org/webgl/resources/webgl-utils.js"></script>
<script>
"use strict";
function main() {
// Get A WebGL context
/** @type {HTMLCanvasElement} */
const canvas = document.querySelector("#canvas");
const gl = canvas.getContext("webgl2");
if (!gl) {
return;
}
gl.viewport(0, 0, canvas.width = window.innerWidth, canvas.height = window.innerHeight);
const vs = `#version 300 es
// an attribute is an input (in) to a vertex shader.
// It will receive data from a buffer
in vec4 a_position;
// all shaders have a main function
void main() {
// gl_Position is a special variable a vertex shader
// is responsible for setting
gl_Position = a_position;
}
`;
const fs = `#version 300 es
precision highp float;
// we need to declare an output for the fragment shader
out vec4 outColor;
uniform vec2 u_resolution;
uniform float u_time;
float random(in vec3 pos) {
return fract(sin(dot(pos.xyz, vec3(70.9898, 78.233, 32.4355))) * 43758.5453123);
}
float random(in vec4 pos) {
float dot_product = dot(pos, vec4(12.9898,78.233,45.164,94.673));
return fract(sin(dot_product) * 43758.5453);
}
void main() {
vec4 color = vec4(vec3(0.0), 1.0);
color += random(vec3(gl_FragCoord.xy / u_resolution * 5.0,u_time)); // return reddish-purple
//color += vec4(gl_PointCoord.xy,0.0,0.0);
outColor = color;
}
`;
// setup GLSL program
const program = webglUtils.createProgramFromSources(gl, [vs, fs]);
// look up where the vertex data needs to go.
const positionAttributeLocation = gl.getAttribLocation(program, "a_position");
// Create a vertex array object (attribute state)
const vao = gl.createVertexArray();
// and make it the one we're currently working with
gl.bindVertexArray(vao);
// Create a buffer to put three 2d clip space points in
const positionBuffer = gl.createBuffer();
// Bind it to ARRAY_BUFFER (think of it as ARRAY_BUFFER = positionBuffer)
gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
// fill it with a 2 triangles that cover clip space
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([
-1, -1, // first triangle
1, -1,
-1, 1,
-1, 1, // second triangle
1, -1,
1, 1,
]), gl.STATIC_DRAW);
// Turn on the attribute
gl.enableVertexAttribArray(positionAttributeLocation);
// Tell the attribute how to get data out of positionBuffer (ARRAY_BUFFER)
gl.vertexAttribPointer(
positionAttributeLocation,
2, // 2 components per iteration
gl.FLOAT, // the data is 32bit floats
false, // don't normalize the data
0, // 0 = move forward size * sizeof(type) each iteration to get the next position
0, // start at the beginning of the buffer
);
var start = Date.now();
function render(){
webglUtils.resizeCanvasToDisplaySize(gl.canvas);
// Tell WebGL how to convert from clip space to pixels
gl.viewport(0, 0, gl.canvas.width, gl.canvas.height);
// Tell it to use our program (pair of shaders)
gl.useProgram(program);
program.createUniform = function (type, name) {
var location = gl.getUniformLocation(program, name);
return function (v1, v2, v3, v4) {
gl['uniform' + type](location, v1, v2, v3, v4);
}
};
//const u_timeloc = gl.getUniformLocation(program, "u_time");
//gl.uniformf(u_timeloc,time);
var tm = program.createUniform('1f', 'u_time');
tm(start)
var res = program.createUniform('2f', 'u_resolution');
res(gl.canvas.width, gl.canvas.height)
// Bind the attribute/buffer set we want.
gl.bindVertexArray(vao);
tm((Date.now() - start)/100000);
// draw 2 triangles
gl.drawArrays(
gl.TRIANGLES,
0, // offset
6, // num vertices to process
);
requestAnimationFrame(render);
}
requestAnimationFrame(render);
}
main();
</script>
</body>
</html>