Fix error report when active color buffer has no fs output

src/libANGLE/ErrorStrings.h

@@ -84,6 +84,7 @@ MSG kDestinationLevelNotDefined = "The destination level of the destination text
 MSG kDestinationTextureTooSmall = "Destination texture too small.";
 MSG kDimensionsMustBePow2 = "Texture dimensions must be power-of-two.";
 MSG kDispatchIndirectBufferNotBound = "Dispatch indirect buffer must be bound.";
+MSG kDrawBufferMaskMismatch = "Active draw buffers with missing fragment shader outputs.";
 MSG kDrawBufferTypeMismatch = "Fragment shader output type does not match the bound framebuffer attachment type.";
 MSG kDrawFramebufferIncomplete = "Draw framebuffer is incomplete";
 MSG kDrawIndirectBufferNotBound = "Draw indirect buffer must be bound.";

src/libANGLE/renderer/gl/ContextGL.cpp

@@ -200,13 +200,6 @@ ANGLE_INLINE angle::Result ContextGL::setDrawArraysState(const gl::Context *cont
                                             count, instanceCount));
     }
 
-    if (context->getExtensions().webglCompatibility)
-    {
-        const gl::State &glState     = context->getState();
-        FramebufferGL *framebufferGL = GetImplAs<FramebufferGL>(glState.getDrawFramebuffer());
-        framebufferGL->maskOutInactiveOutputDrawBuffers(context);
-    }
-
     return angle::Result::Continue;
 }
 
@@ -236,24 +229,6 @@ ANGLE_INLINE angle::Result ContextGL::setDrawElementsState(const gl::Context *co
         *outIndices = indices;
     }
 
-    if (context->getExtensions().webglCompatibility)
-    {
-        FramebufferGL *framebufferGL = GetImplAs<FramebufferGL>(glState.getDrawFramebuffer());
-        framebufferGL->maskOutInactiveOutputDrawBuffers(context);
-    }
-
-    return angle::Result::Continue;
-}
-
-ANGLE_INLINE angle::Result ContextGL::setDrawIndirectState(const gl::Context *context)
-{
-    if (context->getExtensions().webglCompatibility)
-    {
-        const gl::State &glState     = context->getState();
-        FramebufferGL *framebufferGL = GetImplAs<FramebufferGL>(glState.getDrawFramebuffer());
-        framebufferGL->maskOutInactiveOutputDrawBuffers(context);
-    }
-
     return angle::Result::Continue;
 }
 
@@ -375,7 +350,6 @@ angle::Result ContextGL::drawArraysIndirect(const gl::Context *context,
                                             gl::PrimitiveMode mode,
                                             const void *indirect)
 {
-    ANGLE_TRY(setDrawIndirectState(context));
     getFunctions()->drawArraysIndirect(ToGLenum(mode), indirect);
     return angle::Result::Continue;
 }
@@ -385,7 +359,6 @@ angle::Result ContextGL::drawElementsIndirect(const gl::Context *context,
                                               gl::DrawElementsType type,
                                               const void *indirect)
 {
-    ANGLE_TRY(setDrawIndirectState(context));
     getFunctions()->drawElementsIndirect(ToGLenum(mode), ToGLenum(type), indirect);
     return angle::Result::Continue;
 }

src/libANGLE/renderer/gl/ContextGL.h

@@ -231,8 +231,6 @@ class ContextGL : public ContextImpl
                                        GLsizei instanceCount,
                                        const void **outIndices);
 
-    angle::Result setDrawIndirectState(const gl::Context *context);
-
   protected:
     std::shared_ptr<RendererGL> mRenderer;
 };

src/libANGLE/renderer/gl/FramebufferGL.cpp

@@ -726,30 +726,6 @@ bool FramebufferGL::isDefault() const
     return mIsDefault;
 }
 
-void FramebufferGL::maskOutInactiveOutputDrawBuffersImpl(const gl::Context *context,
-                                                         DrawBufferMask targetAppliedDrawBuffers)
-{
-
-    ASSERT(mAppliedEnabledDrawBuffers != targetAppliedDrawBuffers);
-    mAppliedEnabledDrawBuffers = targetAppliedDrawBuffers;
-
-    const auto &stateDrawBuffers = mState.getDrawBufferStates();
-    GLsizei drawBufferCount      = static_cast<GLsizei>(stateDrawBuffers.size());
-    ASSERT(drawBufferCount <= IMPLEMENTATION_MAX_DRAW_BUFFERS);
-
-    GLenum drawBuffers[IMPLEMENTATION_MAX_DRAW_BUFFERS];
-    for (GLenum i = 0; static_cast<int>(i) < drawBufferCount; ++i)
-    {
-        drawBuffers[i] = targetAppliedDrawBuffers[i] ? stateDrawBuffers[i] : GL_NONE;
-    }
-
-    const FunctionsGL *functions = GetFunctionsGL(context);
-    StateManagerGL *stateManager = GetStateManagerGL(context);
-
-    ASSERT(stateManager->getFramebufferID(angle::FramebufferBindingDraw) == mFramebufferID);
-    functions->drawBuffers(drawBufferCount, drawBuffers);
-}
-
 void FramebufferGL::syncClearState(const gl::Context *context, GLbitfield mask)
 {
     const FunctionsGL *functions = GetFunctionsGL(context);

src/libANGLE/renderer/gl/FramebufferGL.h

@@ -86,20 +86,6 @@ class FramebufferGL : public FramebufferImpl
     GLuint getFramebufferID() const;
     bool isDefault() const;
 
-    ANGLE_INLINE void maskOutInactiveOutputDrawBuffers(const gl::Context *context)
-    {
-        ASSERT(context->getExtensions().webglCompatibility);
-
-        const gl::DrawBufferMask &maxSet =
-            context->getState().getProgram()->getActiveOutputVariables();
-
-        gl::DrawBufferMask targetAppliedDrawBuffers = mState.getEnabledDrawBuffers() & maxSet;
-        if (mAppliedEnabledDrawBuffers != targetAppliedDrawBuffers)
-        {
-            maskOutInactiveOutputDrawBuffersImpl(context, targetAppliedDrawBuffers);
-        }
-    }
-
   private:
     void syncClearState(const gl::Context *context, GLbitfield mask);
     void syncClearBufferState(const gl::Context *context, GLenum buffer, GLint drawBuffer);

src/libANGLE/validationES.cpp

@@ -362,6 +362,17 @@ bool ValidateTextureMaxAnisotropyValue(Context *context, GLfloat paramValue)
     return true;
 }
 
+bool ValidateFragmentShaderColorBufferMaskMatch(Context *context)
+{
+    const Program *program         = context->getState().getLinkedProgram(context);
+    const Framebuffer *framebuffer = context->getState().getDrawFramebuffer();
+
+    auto drawBufferMask     = framebuffer->getDrawBufferMask().to_ulong();
+    auto fragmentOutputMask = program->getActiveOutputVariables().to_ulong();
+
+    return drawBufferMask == (drawBufferMask & fragmentOutputMask);
+}
+
 bool ValidateFragmentShaderColorBufferTypeMatch(Context *context)
 {
     const Program *program         = context->getState().getLinkedProgram(context);
@@ -2767,6 +2778,12 @@ const char *ValidateDrawStates(Context *context)
                 return kVertexShaderTypeMismatch;
             }
 
+            // Detect that if there's active color buffer without fragment shader output
+            if (!ValidateFragmentShaderColorBufferMaskMatch(context))
+            {
+                return kDrawBufferMaskMismatch;
+            }
+
             // Detect that the color buffer types match the fragment shader output types
             if (!ValidateFragmentShaderColorBufferTypeMatch(context))
             {

src/tests/gl_tests/DrawBuffersTest.cpp

@@ -357,53 +357,6 @@ TEST_P(DrawBuffersTest, DefaultFramebufferDrawBufferQuery)
     EXPECT_EQ(GL_NONE, drawbuffer);
 }
 
-// Tests masking out some of the draw buffers by not writing to them in the program.
-TEST_P(DrawBuffersWebGL2Test, SomeProgramOutputsDisabled)
-{
-    ANGLE_SKIP_TEST_IF(!setupTest());
-
-    // TODO(ynovikov): Investigate the failure (https://anglebug.com/1533)
-    ANGLE_SKIP_TEST_IF(IsWindows() && IsAMD() && IsDesktopOpenGL());
-
-    bool flags[8]  = {false};
-    GLenum bufs[4] = {GL_NONE};
-
-    constexpr GLuint kMaxBuffers     = 4;
-    constexpr GLuint kHalfMaxBuffers = 2;
-
-    // Enable all draw buffers.
-    for (GLuint texIndex = 0; texIndex < kMaxBuffers; texIndex++)
-    {
-        glBindTexture(GL_TEXTURE_2D, mTextures[texIndex]);
-        glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0 + texIndex, GL_TEXTURE_2D,
-                               mTextures[texIndex], 0);
-        bufs[texIndex] = GL_COLOR_ATTACHMENT0 + texIndex;
-
-        // Mask out the first two buffers.
-        flags[texIndex] = texIndex >= kHalfMaxBuffers;
-    }
-
-    GLuint program;
-    setupMRTProgram(flags, &program);
-
-    setDrawBuffers(kMaxBuffers, bufs);
-    drawQuad(program, positionAttrib(), 0.5, 1.0f, true);
-
-    for (GLuint texIndex = 0; texIndex < kHalfMaxBuffers; texIndex++)
-    {
-        verifyAttachment2DUnwritten(texIndex, mTextures[texIndex], GL_TEXTURE_2D, 0);
-    }
-
-    for (GLuint texIndex = kHalfMaxBuffers; texIndex < kMaxBuffers; texIndex++)
-    {
-        verifyAttachment2D(texIndex, mTextures[texIndex], GL_TEXTURE_2D, 0);
-    }
-
-    EXPECT_GL_NO_ERROR();
-
-    glDeleteProgram(program);
-}
-
 // Same as above but adds a state change from a program with different masks after a clear.
 TEST_P(DrawBuffersWebGL2Test, TwoProgramsWithDifferentOutputsAndClear)
 {
@@ -463,7 +416,7 @@ TEST_P(DrawBuffersWebGL2Test, TwoProgramsWithDifferentOutputsAndClear)
     verifyAttachment2DColor(3, mTextures[3], GL_TEXTURE_2D, 0, GLColor::green);
 
     // Draw with MRT program.
-    setDrawBuffers(kMaxBuffers, allBufs);
+    setDrawBuffers(kMaxBuffers, someBufs);
     drawQuad(program, positionAttrib(), 0.5, 1.0f, true);
     ASSERT_GL_NO_ERROR();
 
@@ -473,6 +426,11 @@ TEST_P(DrawBuffersWebGL2Test, TwoProgramsWithDifferentOutputsAndClear)
     verifyAttachment2D(2, mTextures[2], GL_TEXTURE_2D, 0);
     verifyAttachment2D(3, mTextures[3], GL_TEXTURE_2D, 0);
 
+    // Active draw buffers with no fragment output is not allowed.
+    setDrawBuffers(kMaxBuffers, allBufs);
+    drawQuad(program, positionAttrib(), 0.5, 1.0f, true);
+    ASSERT_GL_ERROR(GL_INVALID_OPERATION);
+
     // Clear again. All attachments should be cleared.
     glClear(GL_COLOR_BUFFER_BIT);
     verifyAttachment2DColor(0, mTextures[0], GL_TEXTURE_2D, 0, GLColor::green);

src/tests/gl_tests/MultiviewDrawTest.cpp

@@ -462,8 +462,9 @@ TEST_P(MultiviewDrawValidationTest, IndirectDraw)
         "#version 300 es\n"
         "#extension GL_OVR_multiview2 : require\n"
         "precision mediump float;\n"
+        "out vec4 color;\n"
         "void main()\n"
-        "{}\n";
+        "{color = vec4(1);}\n";
 
     GLVertexArray vao;
     GLBuffer vertexBuffer;
@@ -544,8 +545,9 @@ TEST_P(MultiviewDrawValidationTest, NumViewsMismatch)
         "#version 300 es\n"
         "#extension GL_OVR_multiview2 : require\n"
         "precision mediump float;\n"
+        "out vec4 color;\n"
         "void main()\n"
-        "{}\n";
+        "{color = vec4(1);}\n";
     ANGLE_GL_PROGRAM(program, kVS, kFS);
     glUseProgram(program);
 
@@ -684,6 +686,9 @@ void main()
     GLTexture tex2DArray;
     initOnePixelColorTexture2DMultiLayered(tex2DArray);
 
+    GLenum bufs[] = {GL_NONE};
+    glDrawBuffers(1, bufs);
+
     // Check that drawArrays generates an error when there is an active transform feedback object
     // and the number of views in the draw framebuffer is greater than 1.
     {
@@ -777,6 +782,9 @@ TEST_P(MultiviewDrawValidationTest, ActiveTimeElapsedQuery)
     GLTexture tex2DArr;
     initOnePixelColorTexture2DMultiLayered(tex2DArr);
 
+    GLenum bufs[] = {GL_NONE};
+    glDrawBuffers(1, bufs);
+
     // Check first case.
     {
         glUseProgram(dualViewProgram);

src/tests/gl_tests/WebGLCompatibilityTest.cpp

@@ -4065,7 +4065,7 @@ TEST_P(WebGLCompatibilityTest, FramebufferAttachmentQuery)
     EXPECT_GL_ERROR(GL_INVALID_ENUM);
 }
 
-// Tests the WebGL removal of undefined behavior when attachments aren't written to.
+// Tests WebGL reports INVALID_OPERATION for mismatch of drawbuffers and fragment output
 TEST_P(WebGLCompatibilityTest, DrawBuffers)
 {
     // Make sure we can use at least 4 attachments for the tests.
@@ -4152,12 +4152,12 @@ TEST_P(WebGLCompatibilityTest, DrawBuffers)
 
     GLenum halfDrawBuffers[] = {
         GL_NONE,
+        GL_COLOR_ATTACHMENT1,
         GL_NONE,
-        GL_COLOR_ATTACHMENT2,
         GL_COLOR_ATTACHMENT3,
     };
 
-    // Test that when using gl_FragColor, only the first attachment is written to.
+    // Test that when using gl_FragColor with no-array
     const char *fragESSL1 =
         R"(precision highp float;
 void main()
@@ -4167,28 +4167,10 @@ void main()
     ANGLE_GL_PROGRAM(programESSL1, essl1_shaders::vs::Simple(), fragESSL1);
 
     {
-        ClearEverythingToRed(renderbuffers);
-
         glBindFramebuffer(GL_FRAMEBUFFER, drawFBO);
         DrawBuffers(useEXT, 4, allDrawBuffers);
         drawQuad(programESSL1, essl1_shaders::PositionAttrib(), 0.5, 1.0, true);
-        ASSERT_GL_NO_ERROR();
-
-        CheckColors(renderbuffers, 0b0001, GLColor::green);
-        CheckColors(renderbuffers, 0b1110, GLColor::red);
-    }
-
-    // Test that when using gl_FragColor, but the first draw buffer is 0, then no attachment is
-    // written to.
-    {
-        ClearEverythingToRed(renderbuffers);
-
-        glBindFramebuffer(GL_FRAMEBUFFER, drawFBO);
-        DrawBuffers(useEXT, 4, halfDrawBuffers);
-        drawQuad(programESSL1, essl1_shaders::PositionAttrib(), 0.5, 1.0, true);
-        ASSERT_GL_NO_ERROR();
-
-        CheckColors(renderbuffers, 0b1111, GLColor::red);
+        EXPECT_GL_ERROR(GL_INVALID_OPERATION);
     }
 
     // Test what happens when rendering to a subset of the outputs. There is a behavior difference
@@ -4199,11 +4181,8 @@ void main()
     const char *positionAttrib;
     const char *writeOddOutputsVert;
     const char *writeOddOutputsFrag;
-    GLColor unwrittenColor;
     if (useEXT)
     {
-        // In the extension, when an attachment isn't written to, it should get 0's
-        unwrittenColor      = GLColor(0, 0, 0, 0);
         positionAttrib      = essl1_shaders::PositionAttrib();
         writeOddOutputsVert = essl1_shaders::vs::Simple();
         writeOddOutputsFrag =
@@ -4217,9 +4196,6 @@ void main()
     }
     else
     {
-        // In ES3 if an attachment isn't declared, it shouldn't get written and should be red
-        // because of the preceding clears.
-        unwrittenColor      = GLColor::red;
         positionAttrib      = essl3_shaders::PositionAttrib();
         writeOddOutputsVert = essl3_shaders::vs::Simple();
         writeOddOutputsFrag =
@@ -4235,21 +4211,30 @@ void main()
     }
     ANGLE_GL_PROGRAM(writeOddOutputsProgram, writeOddOutputsVert, writeOddOutputsFrag);
 
-    // Test that attachments not written to get the "unwritten" color
+    // Test that attachments not written to get the "unwritten" color (useEXT)
+    // Or INVALID_OPERATION is generated if there's active draw buffer receive no output
     {
         ClearEverythingToRed(renderbuffers);
 
         glBindFramebuffer(GL_FRAMEBUFFER, drawFBO);
         DrawBuffers(useEXT, 4, allDrawBuffers);
         drawQuad(writeOddOutputsProgram, positionAttrib, 0.5, 1.0, true);
-        ASSERT_GL_NO_ERROR();
 
+        if (useEXT)
+        {
+            ASSERT_GL_NO_ERROR();
             CheckColors(renderbuffers, 0b1010, GLColor::green);
-        CheckColors(renderbuffers, 0b0101, unwrittenColor);
+            // In the extension, when an attachment isn't written to, it should get 0's
+            CheckColors(renderbuffers, 0b0101, GLColor(0, 0, 0, 0));
+        }
+        else
+        {
+            EXPECT_GL_ERROR(GL_INVALID_OPERATION);
+        }
     }
 
-    // Test that attachments not written to get the "unwritten" color but that even when the
-    // extension is used, disabled attachments are not written at all and stay red.
+    // Test that attachments written to get the correct color from shader output but that even when
+    // the extension is used, disabled attachments are not written at all and stay red.
     {
         ClearEverythingToRed(renderbuffers);
 
@@ -4258,9 +4243,8 @@ void main()
         drawQuad(writeOddOutputsProgram, positionAttrib, 0.5, 1.0, true);
         ASSERT_GL_NO_ERROR();
 
-        CheckColors(renderbuffers, 0b1000, GLColor::green);
-        CheckColors(renderbuffers, 0b0100, unwrittenColor);
-        CheckColors(renderbuffers, 0b0011, GLColor::red);
+        CheckColors(renderbuffers, 0b1010, GLColor::green);
+        CheckColors(renderbuffers, 0b0101, GLColor::red);
     }
 }