texImage2D-source-ignores-unpack-alignment.html

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This WPT test may be referenced by the following Test IDs:
- /webgl/texImage2D-source-ignores-unpack-alignment.html - WPT Dashboard Interop Dashboard

<!doctype html>

<meta charset="utf-8">

<title>texImage2D from a TexImageSource ignores UNPACK_ALIGNMENT</title>

<link rel="author" title="mxmgorin" href="mailto:102797145+mxmgorin@users.noreply.github.com">

<link rel="help" href="https://registry.khronos.org/webgl/specs/latest/2.0/#DOM_UPLOAD_UNPACK_PARAMS">

<script src="/resources/testharness.js"></script>

<script src="/resources/testharnessreport.js"></script>

<script>

// A 1x2 source: RGB rows are 3 bytes, not a multiple of the default UNPACK_ALIGNMENT of 4.

function createSource() {

    var canvas = document.createElement("canvas");

    canvas.width = 1;

    canvas.height = 2;

    var ctx = canvas.getContext("2d");

    ctx.fillStyle = "rgb(255, 0, 0)";

    ctx.fillRect(0, 0, 1, 1);

    ctx.fillStyle = "rgb(0, 255, 0)";

    ctx.fillRect(0, 1, 1, 1);

    return canvas;

// Uploads the source into an RGB8 texture and reads its two texels back, row 0 first.

function uploadAndReadBack(flipY) {

    var gl = document.createElement("canvas").getContext("webgl2");

    assert_equals(gl.getParameter(gl.UNPACK_ALIGNMENT), 4);

    gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, flipY);

    gl.bindTexture(gl.TEXTURE_2D, gl.createTexture());

    gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGB8, 1, 2, 0, gl.RGB, gl.UNSIGNED_BYTE, createSource());

    assert_equals(gl.getError(), gl.NO_ERROR, "texImage2D");

    var texture = gl.getParameter(gl.TEXTURE_BINDING_2D);

    gl.bindFramebuffer(gl.FRAMEBUFFER, gl.createFramebuffer());

    gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, texture, 0);

    var pixels = new Uint8Array(8);

    gl.readPixels(0, 0, 1, 2, gl.RGBA, gl.UNSIGNED_BYTE, pixels);

    return [Array.from(pixels.slice(0, 3)), Array.from(pixels.slice(4, 7))];

test(function() {

    assert_array_equals(uploadAndReadBack(false).flat(), [255, 0, 0, 0, 255, 0]);

}, "Rows of a TexImageSource are uploaded packed");

test(function() {

    assert_array_equals(uploadAndReadBack(true).flat(), [0, 255, 0, 255, 0, 0]);

}, "Rows of a TexImageSource are flipped packed with UNPACK_FLIP_Y_WEBGL");

</script>