program-test-1.html

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<!--

Copyright (c) 2019 The Khronos Group Inc.

Use of this source code is governed by an MIT-style license that can be

found in the LICENSE.txt file.

-->

<!DOCTYPE html>

<html>

<head>

<meta charset="utf-8">

<!-- This is a visual test that programs must have both a vertex and

     fragment shader attached; the fixed function pipeline on the

     desktop must remain disabled. -->

<script type="application/javascript">

function log() {

  var s = "";

  for (var i = 0; i < arguments.length; ++i) {

    s += arguments[i] + " ";

  document.getElementById("log").innerHTML += s + "<br>";

function go() {

  var gl = document.getElementById("c").getContext("experimental-webgl");

  gl.clearColor(0.0, 0.0, 0.0, 0.0);

  gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);

  var vs = gl.createShader(gl.VERTEX_SHADER);

  gl.shaderSource(vs, "attribute vec4 aVertex; attribute vec4 aColor; varying vec4 vColor; void main() { vColor = aColor; gl_Position = aVertex; }");

  gl.compileShader(vs);

  var fs = gl.createShader(gl.FRAGMENT_SHADER);

  gl.shaderSource(fs, "precision mediump float; varying vec4 vColor; void main() { gl_FragColor = vColor; }");

  gl.compileShader(fs);

  var prog = gl.createProgram();

  gl.attachShader(prog, vs);

  // don't attach a fragment shader -- may use fixed pipeline on desktop if the implementation doesn't check!

  //gl.attachShader(prog, fs);

  gl.bindAttribLocation(prog, 0, "aVertex");

  gl.bindAttribLocation(prog, 1, "aColor");

  gl.linkProgram(prog);

  var vbuf = gl.createBuffer();

  gl.bindBuffer(gl.ARRAY_BUFFER, vbuf);

  gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([

      -1.0, -1.0, 0.0, 1.0,

      -1.0, 1.0, 0.0, 1.0,

      1.0, -1.0, 0.0, 1.0,

      1.0, 1.0, 0.0, 1.0]), gl.STATIC_DRAW);

  gl.vertexAttribPointer(0, 4, gl.FLOAT, false, 0, 0);

  var cbuf = gl.createBuffer();

  gl.bindBuffer(gl.ARRAY_BUFFER, cbuf);

  gl.bufferData(gl.ARRAY_BUFFER, new Uint8Array([255, 0, 0,

                                                 0, 255, 0,

                                                 0, 0, 255,

                                                 255, 255, 0]), gl.STATIC_DRAW);

  gl.vertexAttribPointer(1, 3, gl.UNSIGNED_BYTE, false, 0, 0);

  gl.enableVertexAttribArray(0);

  gl.enableVertexAttribArray(1);

  gl.useProgram(prog);

  gl.drawArrays(gl.TRIANGLE_STRIP, 0, 4);

  log("glError", "0x" + gl.getError().toString(16));

</script>

</head>

<body onload="go()">

<p>Should be green in the rectangle below:</p>

<canvas style="background: green;" id="c"></canvas>

<div id="log"></div>

</body>

</html>