<!-- Any copyright is dedicated to the Public Domain.
http://creativecommons.org/publicdomain/zero/1.0/ -->
<!doctype html>
<html>
<head>
<meta charset="utf-8"/>
<title>WebGL editor test page</title>
<script id="shader-vs" type="x-shader/x-vertex">
precision lowp float;
void main(void) {
gl_Position = vec4(0, 0, 0, 1); // I'm a vertex shader!
}
</script>
<script id="shader-fs" type="x-shader/x-fragment">
precision lowp float;
varying vec3 vFragmentColor;
void main(void) {
gl_FragColor = vec4(1, 0, 0, 1); // I'm a fragment shader!
}
</script>
</head>
<body>
<canvas width="512" height="512"></canvas>
<script type="text/javascript;version=1.8">
"use strict";
let canvas, gl;
window.onload = function() {
canvas = document.querySelector("canvas");
gl = canvas.getContext("webgl", { preserveDrawingBuffer: true });
let shaderProgram = gl.createProgram();
let vertexShader, fragmentShader;
// Compile and attach the shaders in a random order. The test will
// ensure that the correct vertex and fragment source is retrieved
// regardless of this crazyness.
if (Math.random() > 0.5) {
vertexShader = getShader(gl, "shader-vs");
fragmentShader = getShader(gl, "shader-fs");
} else {
fragmentShader = getShader(gl, "shader-fs");
vertexShader = getShader(gl, "shader-vs");
}
if (Math.random() > 0.5) {
gl.attachShader(shaderProgram, vertexShader);
gl.attachShader(shaderProgram, fragmentShader);
} else {
gl.attachShader(shaderProgram, fragmentShader);
gl.attachShader(shaderProgram, vertexShader);
}
gl.linkProgram(shaderProgram);
}
function getShader(gl, id) {
let script = document.getElementById(id);
let source = script.textContent;
let shader;
if (script.type == "x-shader/x-fragment") {
shader = gl.createShader(gl.FRAGMENT_SHADER);
} else if (script.type == "x-shader/x-vertex") {
shader = gl.createShader(gl.VERTEX_SHADER);
}
gl.shaderSource(shader, source);
gl.compileShader(shader);
return shader;
}
</script>
</body>
</html>