Implement copies from pack buffers to native buffers.

Full support for using pack buffers as vertex buffers or other
binding points requires us to copy through the staging buffer.

BUG=angle:511

Change-Id: Ife0f5390a1a83dfbe0fa0b19db72f3a8b82b6b83
Reviewed-on: https://chromium-review.googlesource.com/198435
Reviewed-by: Shannon Woods <shannonwoods@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>

src/libGLESv2/renderer/d3d11/BufferStorage11.cpp

@@ -82,6 +82,7 @@ class BufferStorage11::TypedBufferStorage11
     DataRevision getDataRevision() const { return mRevision; }
     BufferUsage getUsage() const { return mUsage; }
     size_t getSize() const { return mBufferSize; }
+    bool isMappable() const { return (mUsage == BUFFER_USAGE_STAGING || mUsage == BUFFER_USAGE_PIXEL_PACK); }
 
     void setDataRevision(DataRevision rev) { mRevision = rev; }
 
@@ -274,6 +275,17 @@ void BufferStorage11::copyData(BufferStorage* sourceStorage, size_t size, size_t
         TypedBufferStorage11 *source = sourceStorage11->getLatestStorage();
         if (source && dest)
         {
+            // If copying to/from a pixel pack buffer, we must have a staging or
+            // pack buffer partner, because other native buffers can't be mapped
+            if (dest->getUsage() == BUFFER_USAGE_PIXEL_PACK && !source->isMappable())
+            {
+                source = sourceStorage11->getStagingBuffer();
+            }
+            else if (source->getUsage() == BUFFER_USAGE_PIXEL_PACK && !dest->isMappable())
+            {
+                dest = getStagingBuffer();
+            }
+
             dest->copyFromStorage(source, sourceOffset, size, destOffset);
             dest->setDataRevision(dest->getDataRevision() + 1);
         }
@@ -433,6 +445,18 @@ BufferStorage11::TypedBufferStorage11 *BufferStorage11::getStorage(BufferUsage u
     TypedBufferStorage11 *latestBuffer = getLatestStorage();
     if (latestBuffer && latestBuffer->getDataRevision() > directBuffer->getDataRevision())
     {
+        // if copying from a pack buffer to a non-staging native buffer, we must first
+        // copy through the staging buffer, because other native buffers can't be mapped
+        if (latestBuffer->getUsage() == BUFFER_USAGE_PIXEL_PACK && !directBuffer->isMappable())
+        {
+            NativeBuffer11 *stagingBuffer = getStagingBuffer();
+
+            stagingBuffer->copyFromStorage(latestBuffer, 0, latestBuffer->getSize(), 0);
+            directBuffer->setDataRevision(latestBuffer->getDataRevision());
+
+            latestBuffer = stagingBuffer;
+        }
+
         // if copyFromStorage returns true, the D3D buffer has been recreated
         // and we should update our serial
         if (directBuffer->copyFromStorage(latestBuffer, 0, latestBuffer->getSize(), 0))

tests/angle_tests/ReadPixelsTest.cpp

@@ -240,3 +240,56 @@ TEST_F(ReadPixelsTest, pbo_and_sub_data_offset)
     glUnmapBuffer(GL_ARRAY_BUFFER);
     EXPECT_GL_NO_ERROR();
 }
+
+TEST_F(ReadPixelsTest, draw_with_pbo)
+{
+    unsigned char data[4] = { 1, 2, 3, 4 };
+
+    glBindTexture(GL_TEXTURE_2D, mTexture);
+    glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 1, 1, GL_RGBA, GL_UNSIGNED_BYTE, data);
+    EXPECT_GL_NO_ERROR();
+
+    // glReadBuffer(GL_COLOR_ATTACHMENT0); // FIXME: currently UNIMPLEMENTED
+    glBindFramebuffer(GL_READ_FRAMEBUFFER, mFBO);
+    EXPECT_GL_NO_ERROR();
+
+    glBindBuffer(GL_PIXEL_PACK_BUFFER, mPBO);
+    glReadPixels(0, 0, 1, 1, GL_RGBA, GL_UNSIGNED_BYTE, 0);
+    glBindBuffer(GL_PIXEL_PACK_BUFFER, 0);
+    EXPECT_GL_NO_ERROR();
+
+    float positionData[] = { 0.5f, 0.5f };
+
+    glUseProgram(mProgram);
+    glViewport(0, 0, 1, 1);
+    glBindBuffer(GL_ARRAY_BUFFER, mPositionVBO);
+    glBufferSubData(GL_ARRAY_BUFFER, 0, 1 * 2 * 4, positionData);
+    EXPECT_GL_NO_ERROR();
+
+    GLint positionLocation = glGetAttribLocation(mProgram, "aPosition");
+    EXPECT_NE(-1, positionLocation);
+
+    GLint testLocation = glGetAttribLocation(mProgram, "aTest");
+    EXPECT_NE(-1, testLocation);
+
+    glVertexAttribPointer(positionLocation, 2, GL_FLOAT, GL_FALSE, 0, 0);
+    glEnableVertexAttribArray(positionLocation);
+    EXPECT_GL_NO_ERROR();
+
+    glBindBuffer(GL_ARRAY_BUFFER, mPBO);
+    glVertexAttribPointer(testLocation, 4, GL_UNSIGNED_BYTE, GL_FALSE, 0, 0);
+    glEnableVertexAttribArray(testLocation);
+    EXPECT_GL_NO_ERROR();
+
+    glDrawArrays(GL_POINTS, 0, 1);
+    EXPECT_GL_NO_ERROR();
+
+    memset(data, 0, 4);
+    glReadPixels(0, 0, 1, 1, GL_RGBA, GL_UNSIGNED_BYTE, data);
+    EXPECT_GL_NO_ERROR();
+
+    EXPECT_EQ(1, data[0]);
+    EXPECT_EQ(2, data[1]);
+    EXPECT_EQ(3, data[2]);
+    EXPECT_EQ(4, data[3]);
+}