readpixels-4gb-wasm-memory.html

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<title>gl.readPixels() test to Wasm Memory 4GB in size.</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>

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<script>

"use strict";

description(document.title);

debug("Tests that gl.readPixels() can be called on WebAssembly Memory of 4GB in size.");

debug("");

let wtu = WebGLTestUtils;

let gl = wtu.create3DContext("canvas", undefined, 2);

const PAGE = 65536;

const SIZE = 4*1024*1024*1024 - PAGE; // when uint32_t size is max, we can only reach one page short of full 4GB

let view = new Uint8Array(new WebAssembly.Memory({ initial: SIZE/PAGE }).buffer);

// Clear the canvas to a specific color

const expectedColor = [42, 84, 128, 255];

gl.clearColor(expectedColor[0]/255.0, expectedColor[1]/255.0, expectedColor[2]/255.0, expectedColor[3]/255.0);

gl.clear(gl.COLOR_BUFFER_BIT);

// Test that gl.readPixels() can be called with a high offset to Memory

const offset = SIZE - 4;

view.set([0,0,0,0], offset); // For good measure, clear data at offset before reading

gl.readPixels(0, 0, 1, 1, gl.RGBA, gl.UNSIGNED_BYTE, view, offset);

wtu.glErrorShouldBe(gl, gl.NO_ERROR);

let obtainedColor = view.subarray(offset, offset+4);

shouldBe('obtainedColor[0]', 'expectedColor[0]');

shouldBe('obtainedColor[1]', 'expectedColor[1]');

shouldBe('obtainedColor[2]', 'expectedColor[2]');

shouldBe('obtainedColor[3]', 'expectedColor[3]');

var successfullyParsed = true;

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