Test for having the same read and write buffer using a transform feed…

…back note: there are 2 lines marked as "FIXME" that I believe should be removed assuming the spec changes so that `gl.bindBuffer` is less strict
KhronosGroup · Mar 25, 2017 · 8b75c1b · 8b75c1b
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diff --git a/sdk/tests/conformance2/transform_feedback/00_test_list.txt b/sdk/tests/conformance2/transform_feedback/00_test_list.txt
@@ -1,3 +1,4 @@
 transform_feedback.html
+transform_feedback_same_buffers_as_input_and_output.html
 two-unreferenced-varyings.html
 unwritten-output-defaults-to-zero.html
diff --git a/.../conformance2/transform_feedback/transform_feedback_same_buffers_as_input_and_output.html b/.../conformance2/transform_feedback/transform_feedback_same_buffers_as_input_and_output.html
@@ -0,0 +1,153 @@
+<!--
+
+/*
+** Copyright (c) 2015 The Khronos Group Inc.
+**
+** Permission is hereby granted, free of charge, to any person obtaining a
+** copy of this software and/or associated documentation files (the
+** "Materials"), to deal in the Materials without restriction, including
+** without limitation the rights to use, copy, modify, merge, publish,
+** distribute, sublicense, and/or sell copies of the Materials, and to
+** permit persons to whom the Materials are furnished to do so, subject to
+** the following conditions:
+**
+** The above copyright notice and this permission notice shall be included
+** in all copies or substantial portions of the Materials.
+**
+** THE MATERIALS ARE PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+** EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+** MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+** IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+** CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+** TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+** MATERIALS OR THE USE OR OTHER DEALINGS IN THE MATERIALS.
+*/
+
+-->
+
+<!DOCTYPE html>
+<html>
+<head>
+<meta charset="utf-8">
+<title>WebGL Transform Feedback Conformance Test - Same Buffers as Input and Output</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: 50px; height: 50px;"> </canvas>
+<div id="console"></div>
+<script id="vshader" type="x-shader/x-vertex">#version 300 es
+in float in_value;
+out float out_value;
+
+void main() {
+   out_value = in_value * 2.;
+}
+</script>
+<script id="fshader" type="x-shader/x-fragment">#version 300 es
+precision mediump float;
+out vec4 dummy;
+void main() {
+  dummy = vec4(1);
+}
+</script>
+<script>
+"use strict";
+description("This test verifies trying to read and write from the same buffers fails");
+
+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");
+
+    runSameInputOutputTest();
+    finishTest();
+}
+
+function runSameInputOutputTest() {
+  const prog = wtu.setupTransformFeedbackProgram(gl, ["vshader", "fshader"],
+      ["out_value"], gl.SEPARATE_ATTRIBS,
+      ["in_value"]);
+  wtu.glErrorShouldBe(gl, gl.NO_ERROR, "linking transform feedback shader should not set an error");
+
+  const inLoc = 0;
+  const outLoc = 0;
+
+  const srcBuffer1 = createBuffer(gl, new Float32Array([1, 2, 3]));
+  const srcVAO1 = createVAO(gl, srcBuffer1, inLoc);
+
+  const dstBuffer = createBuffer(gl, Float32Array.BYTES_PER_ELEMENT * 3);
+  const srcVAO2 = createVAO(gl, dstBuffer, inLoc);
+
+  const tf = gl.createTransformFeedback();
+  gl.bindTransformFeedback(gl.TRANSFORM_FEEDBACK, tf);
+  gl.useProgram(prog);
+  gl.bindBufferBase(gl.TRANSFORM_FEEDBACK_BUFFER, 0, dstBuffer);
+  // this binds the default (id = 0) TRANSFORM_FEEBACK buffer
+  gl.bindTransformFeedback(gl.TRANSFORM_FEEDBACK, null);
+
+  runFeedback(gl, prog, srcVAO1, tf);
+  wtu.glErrorShouldBe(gl, gl.NO_ERROR, "there should be no errors");
+
+  const expected = [2, 4, 6];
+  gl.bindBuffer(gl.ARRAY_BUFFER, dstBuffer);
+  wtu.checkFloatBuffer(gl, gl.ARRAY_BUFFER, expected);
+
+  // this should fail because the transform feedback's buffer #0 and the
+  // srcVAO2's buffer #0 are the same buffer
+  runFeedback(gl, prog, srcVAO2, tf);
+  wtu.glErrorShouldBe(gl, gl.INVALID_OPERATION, "reading and writing to same buffer");
+
+  gl.bindBuffer(gl.ARRAY_BUFFER, dstBuffer);
+  wtu.checkFloatBuffer(gl, gl.ARRAY_BUFFER, expected, "should be the same as before as nothing has executed");
+
+}
+
+function runFeedback(gl, prog, srcVAO, tf, dstBufferInfo) {
+  gl.enable(gl.RASTERIZER_DISCARD);
+
+  gl.useProgram(prog);
+  gl.bindVertexArray(srcVAO);
+
+  gl.bindTransformFeedback(gl.TRANSFORM_FEEDBACK, tf);
+  gl.beginTransformFeedback(gl.TRIANGLES);
+  wtu.glErrorShouldBe(gl, gl.NO_ERROR, "there should be no errors");
+  gl.drawArrays(gl.TRIANGLES, 0, 3);
+  gl.endTransformFeedback();
+
+  // FIXME: this should not be needed once the spec and implementationsa are fixed
+  gl.bindTransformFeedback(gl.TRANSFORM_FEEDBACK, null);
+
+  gl.disable(gl.RASTERIZER_DISCARD);
+}
+
+function createBuffer(gl, dataOrSize) {
+  const buf = gl.createBuffer();
+  gl.bindBuffer(gl.ARRAY_BUFFER, buf);
+  gl.bufferData(gl.ARRAY_BUFFER, dataOrSize, gl.STATIC_DRAW);
+  return buf;
+}
+
+function createVAO(gl, buf, inLoc) {
+  const vao = gl.createVertexArray();
+  gl.bindVertexArray(vao);
+  gl.bindBuffer(gl.ARRAY_BUFFER, buf);
+  gl.enableVertexAttribArray(inLoc);
+  gl.vertexAttribPointer(inLoc, 1, gl.FLOAT, false, 0, 0);
+  // FIXME: this should not be needed once the spec and implementationsa are fixed
+  gl.bindBuffer(gl.ARRAY_BUFFER, null);  // this is not needed
+  gl.bindVertexArray(null);
+  return vao;
+}
+</script>
+
+</body>
+</html>