commit 02032bda51852a851501cbf7a2380ae67f2f7b05
author Olli Etuaho <oetuaho@nvidia.com> Fri Oct 13 18:10:17 2017 +0300
committer Commit Bot <commit-bot@chromium.org> Thu Oct 19 15:50:05 2017 +0000
tree a8757d0bd76b2b837f41cca598cc5cb4832fb3b2
parent cbcb96fcda67b3059f92486f295bc2cfcb8e2d53

Generate an error if no XFB varyings are in use

GLES specifies an error if BeginTransformFeedback is called when no
binding points would be used.

BUG=angleproject:2184
TEST=angle_end2end_tests

Change-Id: Ie4489b5ba63885e718dafdcdaacc02b603959be3
Reviewed-on: https://chromium-review.googlesource.com/719136
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>

src/libANGLE/ErrorStrings.h

diff --git a/src/libANGLE/ErrorStrings.h b/src/libANGLE/ErrorStrings.h
index 9129f25..e056093 100644
--- a/src/libANGLE/ErrorStrings.h
+++ b/src/libANGLE/ErrorStrings.h
@@ -125,6 +125,8 @@
 ERRMSG(NegativeStart, "Cannot have negative start.");
 ERRMSG(NegativeStride, "Cannot have negative stride.");
 ERRMSG(NoSuchPath, "No such path object.");
+ERRMSG(NoTransformFeedbackOutputVariables,
+    "The active program has specified no output variables to record.");
 ERRMSG(NoZeroDivisor, "At least one enabled attribute must have a divisor of zero.");
 ERRMSG(ObjectNotGenerated, "Object cannot be used because it has not been generated.");
 ERRMSG(OffsetMustBeMultipleOfType, "Offset must be a multiple of the passed in datatype.");

src/libANGLE/validationES3.cpp

diff --git a/src/libANGLE/validationES3.cpp b/src/libANGLE/validationES3.cpp
index 4f9c1e1..37a76d3 100644
--- a/src/libANGLE/validationES3.cpp
+++ b/src/libANGLE/validationES3.cpp
@@ -2139,6 +2139,20 @@
         }
     }
 
+    auto program = context->getGLState().getProgram();
+
+    if (!program)
+    {
+        ANGLE_VALIDATION_ERR(context, InvalidOperation(), ProgramNotBound);
+        return false;
+    }
+
+    if (program->getTransformFeedbackVaryingCount() == 0)
+    {
+        ANGLE_VALIDATION_ERR(context, InvalidOperation(), NoTransformFeedbackOutputVariables);
+        return false;
+    }
+
     return true;
 }
 

src/tests/gl_tests/TransformFeedbackTest.cpp

diff --git a/src/tests/gl_tests/TransformFeedbackTest.cpp b/src/tests/gl_tests/TransformFeedbackTest.cpp
index 47e17c6..dc7df16 100644
--- a/src/tests/gl_tests/TransformFeedbackTest.cpp
+++ b/src/tests/gl_tests/TransformFeedbackTest.cpp
@@ -1321,6 +1321,52 @@
     ASSERT_GL_NO_ERROR();
 }
 
+// Test that calling BeginTransformFeedback when no program is currentwill generate an
+// INVALID_OPERATION error.
+TEST_P(TransformFeedbackTest, NoCurrentProgram)
+{
+    glUseProgram(0);
+    glBeginTransformFeedback(GL_TRIANGLES);
+
+    // GLES 3.0.5 section 2.15.2: "The error INVALID_OPERATION is also generated by
+    // BeginTransformFeedback if no binding points would be used, either because no program object
+    // is active or because the active program object has specified no output variables to record."
+    EXPECT_GL_ERROR(GL_INVALID_OPERATION);
+}
+
+// Test that calling BeginTransformFeedback when no transform feedback varyings are in use will
+// generate an INVALID_OPERATION error.
+TEST_P(TransformFeedbackTest, NoTransformFeedbackVaryingsInUse)
+{
+    const std::string &vertexShaderSource =
+        "#version 300 es\n"
+        "in vec4 a_position;\n"
+        "void main()\n"
+        "{\n"
+        "    gl_Position = a_position;\n"
+        "}\n";
+
+    const std::string &fragmentShaderSource =
+        "#version 300 es\n"
+        "precision mediump float;\n"
+        "out vec4 fragColor;\n"
+        "void main()\n"
+        "{\n"
+        "    fragColor = vec4(0);\n"
+        "}\n";
+
+    ANGLE_GL_PROGRAM(program, vertexShaderSource, fragmentShaderSource);
+
+    glUseProgram(program);
+    glBeginTransformFeedback(GL_TRIANGLES);
+
+    // GLES 3.0.5 section 2.15.2: "The error INVALID_OPERATION is also generated by
+    // BeginTransformFeedback if no binding points would be used, either because no program object
+    // is active or because the active program object has specified no output variables to record."
+
+    EXPECT_GL_ERROR(GL_INVALID_OPERATION);
+}
+
 // Use this to select which configurations (e.g. which renderer, which GLES major version) these
 // tests should be run against.
 ANGLE_INSTANTIATE_TEST(TransformFeedbackTest, ES3_D3D11(), ES3_OPENGL(), ES3_OPENGLES());