Adds the PBO extension test

tests/angle_tests/PBOExtensionTest.cpp

+#include "ANGLETest.h"
+
+class PBOExtensionTest : public ANGLETest
+{
+protected:
+    PBOExtensionTest()
+    {
+        setClientVersion(2);
+        setWindowWidth(32);
+        setWindowHeight(32);
+        setConfigRedBits(8);
+        setConfigGreenBits(8);
+        setConfigBlueBits(8);
+        setConfigAlphaBits(8);
+    }
+
+    virtual void SetUp()
+    {
+        ANGLETest::SetUp();
+
+        if (extensionEnabled("NV_pixel_buffer_object"))
+        {
+            glGenBuffers(1, &mPBO);
+            glBindBuffer(GL_PIXEL_PACK_BUFFER, mPBO);
+            glBufferData(GL_PIXEL_PACK_BUFFER, 4 * getWindowWidth() * getWindowHeight(), NULL, GL_STATIC_DRAW);
+            glBindBuffer(GL_PIXEL_PACK_BUFFER, 0);
+
+            const char *vertexShaderSrc = SHADER_SOURCE
+            (
+                attribute vec4 aTest;
+                attribute vec2 aPosition;
+                varying vec4 vTest;
+
+                void main()
+                {
+                    vTest = aTest;
+                    gl_Position = vec4(aPosition, 0.0, 1.0);
+                    gl_PointSize = 1.0;
+                }
+            );
+
+            const char *fragmentShaderSrc = SHADER_SOURCE
+            (
+                precision mediump float;
+                varying vec4 vTest;
+
+                void main()
+                {
+                    gl_FragColor = vTest;
+                }
+            );
+
+            mProgram = compileProgram(vertexShaderSrc, fragmentShaderSrc);
+
+            glGenBuffers(1, &mPositionVBO);
+            glBindBuffer(GL_ARRAY_BUFFER, mPositionVBO);
+            glBufferData(GL_ARRAY_BUFFER, 128, NULL, GL_DYNAMIC_DRAW);
+            glBindBuffer(GL_ARRAY_BUFFER, 0);
+        }
+        ASSERT_GL_NO_ERROR();
+    }
+
+    virtual void TearDown()
+    {
+        ANGLETest::TearDown();
+
+        glDeleteBuffers(1, &mPBO);
+        glDeleteProgram(mProgram);
+    }
+
+    GLuint mPBO;
+    GLuint mProgram;
+    GLuint mPositionVBO;
+};
+
+TEST_F(PBOExtensionTest, pbo_with_other_target)
+{
+    if (extensionEnabled("NV_pixel_buffer_object"))
+    {
+        glClearColor(1.0f, 0.0f, 0.0f, 1.0f);
+        glClear(GL_COLOR_BUFFER_BIT);
+        EXPECT_GL_NO_ERROR();
+
+        glBindBuffer(GL_PIXEL_PACK_BUFFER, mPBO);
+        glReadPixels(0, 0, 16, 16, GL_RGBA, GL_UNSIGNED_BYTE, 0);
+
+        glBindBuffer(GL_PIXEL_PACK_BUFFER, 0);
+        glBindBuffer(GL_ARRAY_BUFFER, mPBO);
+
+        GLvoid *mappedPtr = glMapBufferRangeEXT(GL_ARRAY_BUFFER, 0, 32, GL_MAP_READ_BIT);
+        unsigned char *dataPtr = static_cast<unsigned char *>(mappedPtr);
+        EXPECT_GL_NO_ERROR();
+
+        EXPECT_EQ(255, dataPtr[0]);
+        EXPECT_EQ(0,   dataPtr[1]);
+        EXPECT_EQ(0,   dataPtr[2]);
+        EXPECT_EQ(255, dataPtr[3]);
+
+        glUnmapBufferOES(GL_ARRAY_BUFFER);
+    }
+    EXPECT_GL_NO_ERROR();
+}
+
+TEST_F(PBOExtensionTest, pbo_with_existing_data)
+{
+    if (extensionEnabled("NV_pixel_buffer_object"))
+    {
+        // Clear backbuffer to red
+        glClearColor(1.0f, 0.0f, 0.0f, 1.0f);
+        glClear(GL_COLOR_BUFFER_BIT);
+        EXPECT_GL_NO_ERROR();
+
+        // Read 16x16 region from red backbuffer to PBO
+        glBindBuffer(GL_PIXEL_PACK_BUFFER, mPBO);
+        glReadPixels(0, 0, 16, 16, GL_RGBA, GL_UNSIGNED_BYTE, 0);
+
+        // Clear backbuffer to green
+        glClearColor(0.0f, 1.0f, 0.0f, 1.0f);
+        glClear(GL_COLOR_BUFFER_BIT);
+        EXPECT_GL_NO_ERROR();
+
+        // Read 16x16 region from green backbuffer to PBO at offset 16
+        glReadPixels(0, 0, 16, 16, GL_RGBA, GL_UNSIGNED_BYTE, reinterpret_cast<GLvoid*>(16));
+        GLvoid * mappedPtr = glMapBufferRangeEXT(GL_PIXEL_PACK_BUFFER, 0, 32, GL_MAP_READ_BIT);
+        unsigned char *dataPtr = static_cast<unsigned char *>(mappedPtr);
+        EXPECT_GL_NO_ERROR();
+
+        // Test pixel 0 is red (existing data)
+        EXPECT_EQ(255, dataPtr[0]);
+        EXPECT_EQ(0, dataPtr[1]);
+        EXPECT_EQ(0, dataPtr[2]);
+        EXPECT_EQ(255, dataPtr[3]);
+
+        // Test pixel 16 is green (new data)
+        EXPECT_EQ(0, dataPtr[16 * 4 + 0]);
+        EXPECT_EQ(255, dataPtr[16 * 4 + 1]);
+        EXPECT_EQ(0, dataPtr[16 * 4 + 2]);
+        EXPECT_EQ(255, dataPtr[16 * 4 + 3]);
+
+        glUnmapBufferOES(GL_PIXEL_PACK_BUFFER);
+    }
+    EXPECT_GL_NO_ERROR();
+}