121 lines
3.3 KiB
HTML
121 lines
3.3 KiB
HTML
<!-- Any copyright is dedicated to the Public Domain.
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http://creativecommons.org/publicdomain/zero/1.0/ -->
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<!doctype html>
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<html>
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<head>
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<meta charset="utf-8"/>
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<title>WebGL editor test page</title>
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<script id="shader-vs" type="x-shader/x-vertex">
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precision lowp float;
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attribute vec3 aVertexPosition;
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uniform float uDepth;
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void main(void) {
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gl_Position = vec4(aVertexPosition, uDepth);
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}
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</script>
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<script id="shader-fs-0" type="x-shader/x-fragment">
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precision lowp float;
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void main(void) {
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gl_FragColor = vec4(1.0, 1.0, 0.0, 1.0);
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}
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</script>
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<script id="shader-fs-1" type="x-shader/x-fragment">
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precision lowp float;
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void main(void) {
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gl_FragColor = vec4(0.0, 1.0, 1.0, 1.0);
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}
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</script>
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</head>
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<body>
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<canvas id="canvas" width="128" height="128"></canvas>
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<script type="text/javascript;version=1.8">
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"use strict";
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let canvas, gl;
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let program = [];
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let squareVerticesPositionBuffer;
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let vertexPositionAttribute = [];
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let depthUniform = [];
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window.onload = function() {
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canvas = document.querySelector("canvas");
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gl = canvas.getContext("webgl", { preserveDrawingBuffer: true });
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gl.clearColor(0.0, 0.0, 0.0, 1.0);
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initProgram(0);
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initProgram(1);
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initBuffers();
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drawScene();
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}
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function initProgram(i) {
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let vertexShader = getShader("shader-vs");
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let fragmentShader = getShader("shader-fs-" + i);
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program[i] = gl.createProgram();
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gl.attachShader(program[i], vertexShader);
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gl.attachShader(program[i], fragmentShader);
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gl.linkProgram(program[i]);
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vertexPositionAttribute[i] = gl.getAttribLocation(program[i], "aVertexPosition");
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gl.enableVertexAttribArray(vertexPositionAttribute[i]);
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depthUniform[i] = gl.getUniformLocation(program[i], "uDepth");
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}
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function getShader(id) {
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let script = document.getElementById(id);
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let source = script.textContent;
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let shader;
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if (script.type == "x-shader/x-fragment") {
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shader = gl.createShader(gl.FRAGMENT_SHADER);
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} else if (script.type == "x-shader/x-vertex") {
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shader = gl.createShader(gl.VERTEX_SHADER);
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}
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gl.shaderSource(shader, source);
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gl.compileShader(shader);
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return shader;
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}
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function initBuffers() {
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squareVerticesPositionBuffer = gl.createBuffer();
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gl.bindBuffer(gl.ARRAY_BUFFER, squareVerticesPositionBuffer);
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gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([
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1.0, 1.0, 0.0,
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-1.0, 1.0, 0.0,
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1.0, -1.0, 0.0,
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-1.0, -1.0, 0.0
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]), gl.STATIC_DRAW);
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}
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function drawScene() {
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gl.clear(gl.COLOR_BUFFER_BIT);
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for (let i = 0; i < 2; i++) {
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gl.bindBuffer(gl.ARRAY_BUFFER, squareVerticesPositionBuffer);
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gl.vertexAttribPointer(vertexPositionAttribute[i], 3, gl.FLOAT, false, 0, 0);
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gl.useProgram(program[i]);
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gl.uniform1f(depthUniform[i], i + 1);
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gl.drawArrays(gl.TRIANGLE_STRIP, 0, 4);
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}
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window.requestAnimationFrame(drawScene);
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}
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</script>
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</body>
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</html>
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