<!-- 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> </head> <body> <canvas id="canvas" width="128" height="128"></canvas> <script id="shader-fs" type="x-shader/x-fragment"> precision mediump float; uniform vec4 mtrColor; void main(void) { gl_FragColor = vec4(1.0, 1.0, 1.0, 1.0) * mtrColor; } </script> <script id="shader-vs" type="x-shader/x-vertex"> attribute vec3 aVertexPosition; void main(void) { gl_PointSize = 5.0; gl_Position = vec4(aVertexPosition, 1.0); } </script> <script type="text/javascript;version=1.8"> "use strict"; let canvas, gl, shaderProgram; let triangleVertexPositionBuffer, squareVertexPositionBuffer; window.onload = function() { canvas = document.querySelector("canvas"); gl = canvas.getContext("webgl", { preserveDrawingBuffer: true }); gl.viewportWidth = canvas.width; gl.viewportHeight = canvas.height; initShaders(); initBuffers(); gl.viewport(0, 0, gl.viewportWidth, gl.viewportHeight); gl.clearColor(0.0, 0.0, 0.0, 1.0); gl.disable(gl.DEPTH_TEST); drawScene(); } function getShader(gl, id) { var shaderScript = document.getElementById(id); if (!shaderScript) { return null; } var str = ""; var k = shaderScript.firstChild; while (k) { if (k.nodeType == 3) { str += k.textContent; } k = k.nextSibling; } var shader; if (shaderScript.type == "x-shader/x-fragment") { shader = gl.createShader(gl.FRAGMENT_SHADER); } else if (shaderScript.type == "x-shader/x-vertex") { shader = gl.createShader(gl.VERTEX_SHADER); } else { return null; } gl.shaderSource(shader, str); gl.compileShader(shader); if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) { alert(gl.getShaderInfoLog(shader)); return null; } return shader; } function initShaders() { var fragmentShader = getShader(gl, "shader-fs"); var vertexShader = getShader(gl, "shader-vs"); shaderProgram = gl.createProgram(); gl.attachShader(shaderProgram, vertexShader); gl.attachShader(shaderProgram, fragmentShader); gl.linkProgram(shaderProgram); if (!gl.getProgramParameter(shaderProgram, gl.LINK_STATUS)) { alert("Could not initialise shaders"); } gl.useProgram(shaderProgram); shaderProgram.vertexPositionAttribute = gl.getAttribLocation(shaderProgram, "aVertexPosition"); shaderProgram.pMaterialColor = gl.getUniformLocation(shaderProgram, "mtrColor"); gl.enableVertexAttribArray(shaderProgram.vertexPositionAttribute); } function initBuffers() { // Create triangle vertex/index buffer triangleVertexPositionBuffer = gl.createBuffer(); gl.bindBuffer(gl.ARRAY_BUFFER, triangleVertexPositionBuffer); var vertices = [ 0.0, 0.5, 0.0, -0.5, -0.5, 0.0, 0.5, -0.5, 0.0 ]; gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW); triangleVertexPositionBuffer.itemSize = 3; triangleVertexPositionBuffer.numItems = 3; // Create square vertex/index buffer squareVertexPositionBuffer = gl.createBuffer(); gl.bindBuffer(gl.ARRAY_BUFFER, squareVertexPositionBuffer); vertices = [ 0.8, 0.8, 0.0, -0.8, 0.8, 0.0, 0.8, -0.8, 0.0, -0.8, -0.8, 0.0 ]; gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW); squareVertexPositionBuffer.itemSize = 3; squareVertexPositionBuffer.numItems = 4; } function drawScene() { gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT | gl.STENCIL_BUFFER_BIT); // DrawArrays // -------------- // draw square - triangle strip gl.bindBuffer(gl.ARRAY_BUFFER, squareVertexPositionBuffer); gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute, squareVertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0); gl.uniform4f(shaderProgram.pMaterialColor, 1, 1, 1, 1); gl.drawArrays(gl.TRIANGLE_STRIP, 0, squareVertexPositionBuffer.numItems); // draw square - triangle fan gl.bindBuffer(gl.ARRAY_BUFFER, squareVertexPositionBuffer); gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute, squareVertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0); gl.uniform4f(shaderProgram.pMaterialColor, 0, 1, 0, 1); gl.drawArrays(gl.TRIANGLE_FAN, 0, squareVertexPositionBuffer.numItems); // draw triangle gl.bindBuffer(gl.ARRAY_BUFFER, triangleVertexPositionBuffer); gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute, triangleVertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0); gl.uniform4f(shaderProgram.pMaterialColor, 1, 0, 0, 1); gl.drawArrays(gl.TRIANGLES, 0, triangleVertexPositionBuffer.numItems); // draw points gl.bindBuffer(gl.ARRAY_BUFFER, squareVertexPositionBuffer); gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute, squareVertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0); gl.uniform4f(shaderProgram.pMaterialColor, 1, 0, 1, 1); gl.drawArrays(gl.POINTS, 0, squareVertexPositionBuffer.numItems); // draw lines gl.bindBuffer(gl.ARRAY_BUFFER, squareVertexPositionBuffer); gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute, squareVertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0); gl.uniform4f(shaderProgram.pMaterialColor, 0, 0, 1, 1); gl.lineWidth(8.0); gl.drawArrays(gl.LINES, 0, squareVertexPositionBuffer.numItems); // draw line strip gl.bindBuffer(gl.ARRAY_BUFFER, squareVertexPositionBuffer); gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute, squareVertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0); gl.uniform4f(shaderProgram.pMaterialColor, 0.9, 0.6, 0, 1); gl.lineWidth(3.0); gl.drawArrays(gl.LINE_STRIP, 0, squareVertexPositionBuffer.numItems); // draw line loop gl.bindBuffer(gl.ARRAY_BUFFER, triangleVertexPositionBuffer); gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute, triangleVertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0); gl.uniform4f(shaderProgram.pMaterialColor, 0, 1, 1, 1); gl.lineWidth(3.0); gl.drawArrays(gl.LINE_LOOP, 0, triangleVertexPositionBuffer.numItems); window.requestAnimationFrame(drawScene); } </script> </body> </html>