canvas-clear-on-zero-count-draw.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

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<!DOCTYPE html>

<html>

<head>

<meta charset="utf-8">

<title>Check that the canvas is NOT recomposited after unsucessful draw call</title>

<link rel="stylesheet" href="../../resources/js-test-style.css"/>

<script src="../../js/js-test-pre.js"></script>

<script src="../../js/webgl-test-utils.js"></script>

<style>

canvas {

    border: 1px solid black;

.correct {

    border: 1px solid black;

    background-color: #ffffff;

</style>

</head>

<body>

<pre>

This test must be run manually.

This test tests that a canvas is cleared

even when a draw call has a zero count.

You should see three <span class="correct">white rectangles</span>

with black outlines on success.

</pre>

<canvas id='c1'></canvas>

<canvas id='c2'></canvas>

<canvas id='c3'></canvas>

<div id="console"></div>

<script id="vshader" type="x-shader/x-vertex">

void main() {

  gl_Position = vec4(0,0,0,1);

</script>

<script id="fshader" type="x-shader/x-fragment">

precision mediump float;

void main() {

  discard;

</script>

<script>

"use strict";

var wtu = WebGLTestUtils;

var c1 = document.getElementById("c1");

var c2 = document.getElementById("c2");

var c3 = document.getElementById("c2");

var gl1 = wtu.create3DContext(c1);

var gl2 = wtu.create3DContext(c2);

var gl3 = wtu.create3DContext(c2);

gl1.clearColor(0,1,0,1);

gl1.clear(gl1.COLOR_BUFFER_BIT);

gl2.clearColor(0,1,0,1);

gl2.clear(gl2.COLOR_BUFFER_BIT);

gl3.clearColor(0,1,0,1);

gl3.clear(gl2.COLOR_BUFFER_BIT);

wtu.waitForComposite(function() {

  // test drawArrays

  gl1.drawArrays(gl1.TRIANGLES, 0, 0);

  wtu.glErrorShouldBe(gl1, gl1.NO_ERROR, "no errors");

});

wtu.waitForComposite(function() {

  // test drawElements

  var buf = gl2.createBuffer();

  gl2.bindBuffer(gl2.ELEMENT_ARRAY_BUFFER, buf);

  gl2.bufferData(gl2.ELEMENT_ARRAY_BUFFER, new Uint8Array(1), gl2.STATIC_DRAW);

  gl2.drawElements(gl2.TRIANGLES, 0, gl2.UNSIGNED_SHORT, 0);

  wtu.glErrorShouldBe(gl2, gl2.NO_ERROR, "no errors");

});

wtu.waitForComposite(function() {

  // test draw with program.

  wtu.setupProgram(gl3, ["vshader", "fshader"]);

  gl1.drawArrays(gl3.TRIANGLES, 0, 0);

  wtu.glErrorShouldBe(gl3, gl2.NO_ERROR, "no errors");

});

</script>

</body>

</html>