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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.
*/
'use strict';
description("Verifies that lines, both aliased and antialiased, have acceptable quality.");
let wtu = WebGLTestUtils;
let gl;
let aa_fbo;
function setupWebGL1Test(canvasId, useAntialiasing) {
gl = wtu.create3DContext(canvasId, { antialias: useAntialiasing }, contextVersion);
wtu.glErrorShouldBe(gl, gl.NO_ERROR, "Should be no errors during WebGL 1.0 setup");
}
function setupWebGL2Test(canvasId, useAntialiasing) {
gl = wtu.create3DContext(canvasId, { antialias: false }, contextVersion);
// In WebGL 2.0, we always allocate the back buffer without
// antialiasing. The only question is whether we allocate a
// framebuffer with a multisampled renderbuffer attachment.
aa_fbo = null;
if (useAntialiasing) {
aa_fbo = gl.createFramebuffer();
gl.bindFramebuffer(gl.FRAMEBUFFER, aa_fbo);
let rb = gl.createRenderbuffer();
gl.bindRenderbuffer(gl.RENDERBUFFER, rb);
let supported = gl.getInternalformatParameter(gl.RENDERBUFFER, gl.RGBA8, gl.SAMPLES);
// Prefer 4, then 8, then max.
let preferred = [4, 8];
let allocated = false;
for (let value of preferred) {
if (supported.indexOf(value) >= 0) {
gl.renderbufferStorageMultisample(gl.RENDERBUFFER, value, gl.RGBA8,
gl.drawingBufferWidth, gl.drawingBufferHeight);
allocated = true;
break;
}
}
if (!allocated) {
gl.renderbufferStorageMultisample(gl.RENDERBUFFER, supported[supported.length - 1],
gl.RGBA8, gl.drawingBufferWidth, gl.drawingBufferHeight);
}
gl.framebufferRenderbuffer(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.RENDERBUFFER, rb);
}
wtu.glErrorShouldBe(gl, gl.NO_ERROR, "Should be no errors during WebGL 2.0 setup");
}
function setupLines() {
let prog = wtu.setupSimpleColorProgram(gl, 0);
let loc = gl.getUniformLocation(prog, 'u_color');
if (loc == null) {
testFailed('Failed to fetch color uniform');
}
wtu.glErrorShouldBe(gl, gl.NO_ERROR, "After setup of line program");
gl.uniform4f(loc, 1.0, 1.0, 1.0, 1.0);
let buffer = gl.createBuffer();
let scale = 0.5;
gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([
-scale, -scale, 0.0, 1.0,
-scale, scale, 0.0, 1.0,
scale, scale, 0.0, 1.0,
scale, -scale, 0.0, 1.0,
-scale, -scale, 0.0, 1.0,
]), gl.STATIC_DRAW);
wtu.glErrorShouldBe(gl, gl.NO_ERROR, "After setup of buffer");
gl.vertexAttribPointer(0, 4, gl.FLOAT, false, 0, 0);
gl.enableVertexAttribArray(0);
wtu.glErrorShouldBe(gl, gl.NO_ERROR, "After setup of attribute array");
}
function renderLines(contextVersion, useAntialiasing) {
gl.clearColor(0.0, 0.0, 0.5, 1.0);
gl.clear(gl.COLOR_BUFFER_BIT);
gl.drawArrays(gl.LINE_STRIP, 0, 5);
if (contextVersion == 2 && useAntialiasing) {
// Blit aa_fbo into the real back buffer.
gl.bindFramebuffer(gl.READ_FRAMEBUFFER, aa_fbo);
gl.bindFramebuffer(gl.DRAW_FRAMEBUFFER, null);
let w = gl.drawingBufferWidth;
let h = gl.drawingBufferHeight;
gl.blitFramebuffer(0, 0, w, h,
0, 0, w, h,
gl.COLOR_BUFFER_BIT, gl.NEAREST);
gl.bindFramebuffer(gl.FRAMEBUFFER, null);
}
}
function pixelAboveThreshold(arr, pixelIndex, threshold) {
return (arr[4 * pixelIndex + 0] >= threshold &&
arr[4 * pixelIndex + 1] >= threshold &&
arr[4 * pixelIndex + 2] >= threshold &&
arr[4 * pixelIndex + 3] >= threshold);
}
function checkLine(arr, threshold, direction) {
// Count number of crossings from below threshold to above (or equal
// to) threshold. Must be equal to 2.
let numPixels = arr.length / 4;
let numUpCrossings = 0;
let numDownCrossings = 0;
for (let index = 0; index < numPixels - 1; ++index) {
let curPixel = pixelAboveThreshold(arr, index, threshold);
let nextPixel = pixelAboveThreshold(arr, index + 1, threshold);
if (!curPixel && nextPixel) {
++numUpCrossings;
} else if (curPixel && !nextPixel) {
++numDownCrossings;
}
}
if (numUpCrossings != numDownCrossings) {
testFailed('Found differing numbers of up->down and down->up transitions');
}
if (numUpCrossings == 2) {
testPassed('Found 2 lines, looking in the ' + direction + ' direction');
} else {
testFailed('Found ' + numUpCrossings + ' lines, looking in the ' +
direction + ' direction, expected 2');
}
}
function checkResults() {
// Check the middle horizontal and middle vertical line of the canvas.
let w = gl.drawingBufferWidth;
let h = gl.drawingBufferHeight;
let t = 100;
let arr = new Uint8Array(4 * w);
gl.readPixels(0, Math.floor(h / 2),
w, 1, gl.RGBA, gl.UNSIGNED_BYTE, arr);
checkLine(arr, t, 'horizontal');
arr = new Uint8Array(4 * h);
gl.readPixels(Math.floor(w / 2), 0,
1, h, gl.RGBA, gl.UNSIGNED_BYTE, arr);
checkLine(arr, t, 'vertical');
}
function runTest(contextVersion, canvasId, useAntialiasing) {
switch (contextVersion) {
case 1: {
setupWebGL1Test(canvasId, useAntialiasing);
break;
}
case 2: {
setupWebGL2Test(canvasId, useAntialiasing);
}
}
setupLines();
renderLines(contextVersion, useAntialiasing);
checkResults();
}
function runTests() {
runTest(contextVersion, 'testbed', false);
runTest(contextVersion, 'testbed2', true);
}
runTests();
let successfullyParsed = true;
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