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Add WebGL CTS regression test for switching transform feedback programs #3785

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Merged
kenrussell merged 1 commit into from
Jul 17, 2026
+138 −0
Merged

Add WebGL CTS regression test for switching transform feedback programs #3785

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1 change: 1 addition & 0 deletions sdk/tests/conformance2/transform_feedback/00_test_list.txt
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Expand Up @@ -7,3 +7,4 @@ unwritten-output-defaults-to-zero.html
--min-version 2.0.1 same-buffer-two-binding-points.html
--min-version 2.0.1 simultaneous_binding.html
--min-version 2.0.1 switching-objects.html
--min-version 2.0.1 switching-programs.html
137 changes: 137 additions & 0 deletions sdk/tests/conformance2/transform_feedback/switching-programs.html
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@@ -0,0 +1,137 @@
<!--
Copyright (c) 2026 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">
<title>Switching transform feedback programs</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>
</head>
<body>
<div id="description"></div>
<canvas id="canvas" style="width: 10px; height: 10px;"> </canvas>
<div id="console"></div>
<script>
"use strict";
description("Tests switching programs during paused transform feedback.");

debug("");

var wtu = WebGLTestUtils;
var canvas = document.getElementById("canvas");
var gl = wtu.create3DContext(canvas, null, 2);

if (!gl) {
testFailed("WebGL context does not exist");
} else {
testPassed("WebGL context exists");
runTest();
}

function runTest() {
const vsSource = `#version 300 es
in float a_in;
out float a_out;
void main() {
a_out = a_in;
gl_Position = vec4(0.0, 0.0, 0.0, 1.0);
}
`;
const fsSource = `#version 300 es
precision mediump float;
out vec4 color;
void main() {
color = vec4(1.0);
}
`;

function createProgramWithTF(vsSrc, fsSrc) {
const vs = gl.createShader(gl.VERTEX_SHADER);
gl.shaderSource(vs, vsSrc);
gl.compileShader(vs);
if (!gl.getShaderParameter(vs, gl.COMPILE_STATUS)) {
testFailed("Vertex shader compile failed: " + gl.getShaderInfoLog(vs));
} else {
testPassed("Vertex shader compiled successfully");
}

const fs = gl.createShader(gl.FRAGMENT_SHADER);
gl.shaderSource(fs, fsSrc);
gl.compileShader(fs);
if (!gl.getShaderParameter(fs, gl.COMPILE_STATUS)) {
testFailed("Fragment shader compile failed: " + gl.getShaderInfoLog(fs));
} else {
testPassed("Fragment shader compiled successfully");
}

const prog = gl.createProgram();
gl.attachShader(prog, vs);
gl.attachShader(prog, fs);
gl.transformFeedbackVaryings(prog, ['a_out'], gl.SEPARATE_ATTRIBS);
gl.linkProgram(prog);
if (!gl.getProgramParameter(prog, gl.LINK_STATUS)) {
testFailed("Program linking failed: " + gl.getProgramInfoLog(prog));
} else {
testPassed("Program linked successfully");
}
return prog;
}

const p1 = createProgramWithTF(vsSource, fsSource);
const p2 = createProgramWithTF(vsSource, fsSource);

// Prepare a transform feedback buffer so beginTransformFeedback succeeds.
const tf = gl.createTransformFeedback();
gl.bindTransformFeedback(gl.TRANSFORM_FEEDBACK, tf);
const buf = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, buf);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(16), gl.STATIC_DRAW);
gl.bindBufferBase(gl.TRANSFORM_FEEDBACK_BUFFER, 0, buf);

// Activate P2 and start transform feedback.
gl.useProgram(p2);
gl.beginTransformFeedback(gl.POINTS);
wtu.glErrorShouldBe(gl, gl.NO_ERROR, "beginTransformFeedback with P2 should succeed");

// Pause transform feedback and swap active program to P1.
gl.pauseTransformFeedback();
gl.useProgram(p1);
wtu.glErrorShouldBe(gl, gl.NO_ERROR, "useProgram(P1) while paused should succeed");

// End transform feedback while P1 is current_program_.
gl.endTransformFeedback();
wtu.glErrorShouldBe(gl, gl.NO_ERROR, "endTransformFeedback should succeed");

// Now verify P1's and P2's state when neither is active for transform feedback.
// 1. P1 was the current program during endTransformFeedback, but never active in TF. Re-linking P1 must succeed.
gl.linkProgram(p1);
wtu.glErrorShouldBe(gl, gl.NO_ERROR, "linkProgram(P1) after endTransformFeedback should succeed");

// 2. P2 was the program active during TF, which has now ended. Re-linking P2 must succeed.
gl.linkProgram(p2);
wtu.glErrorShouldBe(gl, gl.NO_ERROR, "linkProgram(P2) after endTransformFeedback should succeed");

// 3. Now start transform feedback with P1 (which is still the current program).
gl.beginTransformFeedback(gl.POINTS);
wtu.glErrorShouldBe(gl, gl.NO_ERROR, "beginTransformFeedback with P1 should succeed");

// Attempt to re-link P1 while it is active for transform feedback.
// This must be rejected with INVALID_OPERATION per specification.
gl.linkProgram(p1);
wtu.glErrorShouldBe(gl, gl.INVALID_OPERATION,
"linkProgram(P1) while active in transform feedback must return INVALID_OPERATION");

gl.endTransformFeedback();
wtu.glErrorShouldBe(gl, gl.NO_ERROR, "final endTransformFeedback should succeed");

finishTest();
}
</script>
</body>
</html>
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