Fix bugs with drawbuffer state.

src/libANGLE/Framebuffer.cpp

@@ -54,6 +54,7 @@ Framebuffer::Data::Data(const Caps &caps)
       mDrawBufferStates(caps.maxDrawBuffers, GL_NONE),
       mReadBufferState(GL_COLOR_ATTACHMENT0_EXT)
 {
+    ASSERT(mDrawBufferStates.size() > 0);
     mDrawBufferStates[0] = GL_COLOR_ATTACHMENT0_EXT;
 }
 
@@ -287,10 +288,15 @@ const FramebufferAttachment *Framebuffer::getAttachment(GLenum attachment) const
     }
 }
 
-GLenum Framebuffer::getDrawBufferState(unsigned int colorAttachment) const
+size_t Framebuffer::getDrawbufferStateCount() const
 {
-    ASSERT(colorAttachment < mData.mDrawBufferStates.size());
-    return mData.mDrawBufferStates[colorAttachment];
+    return mData.mDrawBufferStates.size();
+}
+
+GLenum Framebuffer::getDrawBufferState(size_t drawBuffer) const
+{
+    ASSERT(drawBuffer < mData.mDrawBufferStates.size());
+    return mData.mDrawBufferStates[drawBuffer];
 }
 
 void Framebuffer::setDrawBuffers(size_t count, const GLenum *buffers)
@@ -303,6 +309,36 @@ void Framebuffer::setDrawBuffers(size_t count, const GLenum *buffers)
     mDirtyBits.set(DIRTY_BIT_DRAW_BUFFERS);
 }
 
+const FramebufferAttachment *Framebuffer::getDrawBuffer(size_t drawBuffer) const
+{
+    ASSERT(drawBuffer < mData.mDrawBufferStates.size());
+    if (mData.mDrawBufferStates[drawBuffer] != GL_NONE)
+    {
+        // ES3 spec: "If the GL is bound to a draw framebuffer object, the ith buffer listed in bufs
+        // must be COLOR_ATTACHMENTi or NONE"
+        ASSERT(mData.mDrawBufferStates[drawBuffer] == GL_COLOR_ATTACHMENT0 + drawBuffer ||
+               (drawBuffer == 0 && mData.mDrawBufferStates[drawBuffer] == GL_BACK));
+        return getAttachment(mData.mDrawBufferStates[drawBuffer]);
+    }
+    else
+    {
+        return nullptr;
+    }
+}
+
+bool Framebuffer::hasEnabledDrawBuffer() const
+{
+    for (size_t drawbufferIdx = 0; drawbufferIdx < mData.mDrawBufferStates.size(); ++drawbufferIdx)
+    {
+        if (getDrawBuffer(drawbufferIdx) != nullptr)
+        {
+            return true;
+        }
+    }
+
+    return false;
+}
+
 GLenum Framebuffer::getReadBufferState() const
 {
     return mData.mReadBufferState;
@@ -317,26 +353,6 @@ void Framebuffer::setReadBuffer(GLenum buffer)
     mDirtyBits.set(DIRTY_BIT_READ_BUFFER);
 }
 
-bool Framebuffer::isEnabledColorAttachment(size_t colorAttachment) const
-{
-    ASSERT(colorAttachment < mData.mColorAttachments.size());
-    return (mData.mColorAttachments[colorAttachment].isAttached() &&
-            mData.mDrawBufferStates[colorAttachment] != GL_NONE);
-}
-
-bool Framebuffer::hasEnabledColorAttachment() const
-{
-    for (size_t colorAttachment = 0; colorAttachment < mData.mColorAttachments.size(); ++colorAttachment)
-    {
-        if (isEnabledColorAttachment(static_cast<unsigned int>(colorAttachment)))
-        {
-            return true;
-        }
-    }
-
-    return false;
-}
-
 size_t Framebuffer::getNumColorBuffers() const
 {
     return mData.mColorAttachments.size();
@@ -354,9 +370,9 @@ bool Framebuffer::hasStencil() const
 
 bool Framebuffer::usingExtendedDrawBuffers() const
 {
-    for (size_t colorAttachment = 1; colorAttachment < mData.mColorAttachments.size(); ++colorAttachment)
+    for (size_t drawbufferIdx = 1; drawbufferIdx < mData.mDrawBufferStates.size(); ++drawbufferIdx)
     {
-        if (isEnabledColorAttachment(static_cast<unsigned int>(colorAttachment)))
+        if (getDrawBuffer(drawbufferIdx) != nullptr)
         {
             return true;
         }

src/libANGLE/Framebuffer.h

@@ -117,14 +117,15 @@ class Framebuffer final : public LabeledObject
 
     const FramebufferAttachment *getAttachment(GLenum attachment) const;
 
-    GLenum getDrawBufferState(unsigned int colorAttachment) const;
+    size_t getDrawbufferStateCount() const;
+    GLenum getDrawBufferState(size_t drawBuffer) const;
     void setDrawBuffers(size_t count, const GLenum *buffers);
+    const FramebufferAttachment *getDrawBuffer(size_t drawBuffer) const;
+    bool hasEnabledDrawBuffer() const;
 
     GLenum getReadBufferState() const;
     void setReadBuffer(GLenum buffer);
 
-    bool isEnabledColorAttachment(size_t colorAttachment) const;
-    bool hasEnabledColorAttachment() const;
     size_t getNumColorBuffers() const;
     bool hasDepth() const;
     bool hasStencil() const;

src/libANGLE/renderer/d3d/FramebufferD3D.cpp

@@ -54,7 +54,7 @@ ClearParameters GetClearParameters(const gl::State &state, GLbitfield mask)
     const gl::Framebuffer *framebufferObject = state.getDrawFramebuffer();
     if (mask & GL_COLOR_BUFFER_BIT)
     {
-        if (framebufferObject->hasEnabledColorAttachment())
+        if (framebufferObject->hasEnabledDrawBuffer())
         {
             for (unsigned int i = 0; i < ArraySize(clearParams.clearColor); i++)
             {

src/libANGLE/renderer/gl/renderergl_utils.cpp

@@ -244,6 +244,9 @@ void GenerateCaps(const FunctionsGL *functions, gl::Caps *caps, gl::TextureCapsM
     }
     else
     {
+        // Framebuffer is required to have at least one drawbuffer even if the extension is not
+        // supported
+        caps->maxDrawBuffers = 1;
         LimitVersion(maxSupportedESVersion, gl::Version(2, 0));
     }
 

src/libANGLE/validationES.cpp

@@ -682,11 +682,14 @@ bool ValidateBlitFramebufferParameters(gl::Context *context,
             GLenum readInternalFormat = readColorBuffer->getInternalFormat();
             const InternalFormat &readFormatInfo = GetInternalFormatInfo(readInternalFormat);
 
-            for (size_t i = 0; i < drawFramebuffer->getNumColorBuffers(); i++)
+            for (size_t drawbufferIdx = 0;
+                 drawbufferIdx < drawFramebuffer->getDrawbufferStateCount(); ++drawbufferIdx)
             {
-                if (drawFramebuffer->isEnabledColorAttachment(i))
+                const FramebufferAttachment *attachment =
+                    drawFramebuffer->getDrawBuffer(drawbufferIdx);
+                if (attachment)
                 {
-                    GLenum drawInternalFormat = drawFramebuffer->getColorbuffer(i)->getInternalFormat();
+                    GLenum drawInternalFormat            = attachment->getInternalFormat();
                     const InternalFormat &drawFormatInfo = GetInternalFormatInfo(drawInternalFormat);
 
                     // The GL ES 3.0.2 spec (pg 193) states that:

src/libANGLE/validationES2.cpp

@@ -1602,15 +1602,13 @@ bool ValidateBlitFramebufferANGLE(Context *context,
                 return false;
             }
 
-            for (size_t colorAttachment = 0;
-                 colorAttachment < drawFramebuffer->getNumColorBuffers(); ++colorAttachment)
+            for (size_t drawbufferIdx = 0;
+                 drawbufferIdx < drawFramebuffer->getDrawbufferStateCount(); ++drawbufferIdx)
             {
-                if (drawFramebuffer->isEnabledColorAttachment(colorAttachment))
+                const FramebufferAttachment *attachment =
+                    drawFramebuffer->getDrawBuffer(drawbufferIdx);
+                if (attachment)
                 {
-                    const FramebufferAttachment *attachment =
-                        drawFramebuffer->getColorbuffer(colorAttachment);
-                    ASSERT(attachment);
-
                     if (!(attachment->type() == GL_TEXTURE &&
                           attachment->getTextureImageIndex().type == GL_TEXTURE_2D) &&
                         attachment->type() != GL_RENDERBUFFER &&

src/tests/gl_tests/DrawBuffersTest.cpp

@@ -38,7 +38,8 @@ class DrawBuffersTest : public ANGLETest
         for (size_t texIndex = 0; texIndex < ArraySize(mTextures); texIndex++)
         {
             glBindTexture(GL_TEXTURE_2D, mTextures[texIndex]);
-            glTexStorage2DEXT(GL_TEXTURE_2D, 1, GL_RGBA8, getWindowWidth(), getWindowHeight());
+            glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, getWindowWidth(), getWindowHeight(), 0, GL_RGBA,
+                         GL_UNSIGNED_BYTE, nullptr);
         }
 
         GLfloat data[] =
@@ -231,6 +232,13 @@ TEST_P(DrawBuffersTest, VerifyD3DLimits)
 
 TEST_P(DrawBuffersTest, Gaps)
 {
+    if (getClientVersion() < 3 && !extensionEnabled("GL_EXT_draw_buffers"))
+    {
+        std::cout << "Test skipped because ES3 or GL_EXT_draw_buffers is not available."
+                  << std::endl;
+        return;
+    }
+
     glBindTexture(GL_TEXTURE_2D, mTextures[0]);
     glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT1, GL_TEXTURE_2D, mTextures[0], 0);
 
@@ -255,6 +263,13 @@ TEST_P(DrawBuffersTest, Gaps)
 
 TEST_P(DrawBuffersTest, FirstAndLast)
 {
+    if (getClientVersion() < 3 && !extensionEnabled("GL_EXT_draw_buffers"))
+    {
+        std::cout << "Test skipped because ES3 or GL_EXT_draw_buffers is not available."
+                  << std::endl;
+        return;
+    }
+
     glBindTexture(GL_TEXTURE_2D, mTextures[0]);
     glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, mTextures[0], 0);
 
@@ -288,6 +303,13 @@ TEST_P(DrawBuffersTest, FirstAndLast)
 
 TEST_P(DrawBuffersTest, FirstHalfNULL)
 {
+    if (getClientVersion() < 3 && !extensionEnabled("GL_EXT_draw_buffers"))
+    {
+        std::cout << "Test skipped because ES3 or GL_EXT_draw_buffers is not available."
+                  << std::endl;
+        return;
+    }
+
     bool flags[8] = { false };
     GLenum bufs[8] = { GL_NONE };
 
@@ -320,6 +342,13 @@ TEST_P(DrawBuffersTest, FirstHalfNULL)
 
 TEST_P(DrawBuffersTest, UnwrittenOutputVariablesShouldNotCrash)
 {
+    if (getClientVersion() < 3 && !extensionEnabled("GL_EXT_draw_buffers"))
+    {
+        std::cout << "Test skipped because ES3 or GL_EXT_draw_buffers is not available."
+                  << std::endl;
+        return;
+    }
+
     // Bind two render targets but use a shader which writes only to the first one.
     glBindTexture(GL_TEXTURE_2D, mTextures[0]);
     glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, mTextures[0], 0);