gpu/command_buffer/tests/gl_ext_multisample_compatibility_unittest.cc - chromium/src - Git at Google

 // Copyright (c) 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 #include <GLES2/gl2.h>
 #include <GLES2/gl2ext.h>
 #include <GLES2/gl2extchromium.h>
 #include <stdint.h>

 #include <memory>

 #include "gpu/command_buffer/tests/gl_manager.h"
 #include "gpu/command_buffer/tests/gl_test_utils.h"
 #include "gpu/config/gpu_test_config.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/gl/gl_context.h"

 #define SHADER0(Src) #Src

 namespace gpu {

 class EXTMultisampleCompatibilityTest : public testing::Test {
  public:
  protected:
   static const GLuint kWidth = 100;
   static const GLuint kHeight = 100;

   void SetUp() override { gl_.Initialize(GLManager::Options()); }

   void TearDown() override { gl_.Destroy(); }

   void PrepareForDraw() {
     static const char* v_shader_str = SHADER0(
         attribute vec4 a_Position; void main() { gl_Position = a_Position; });
     static const char* f_shader_str =
         SHADER0(precision mediump float; uniform vec4 color;
                 void main() { gl_FragColor = color; });

     GLuint program = GLTestHelper::LoadProgram(v_shader_str, f_shader_str);
     glUseProgram(program);
     GLuint position_loc = glGetAttribLocation(program, "a_Position");
     color_loc_ = glGetUniformLocation(program, "color");

     GLuint vbo = 0;
     glGenBuffers(1, &vbo);
     glBindBuffer(GL_ARRAY_BUFFER, vbo);
     static float vertices[] = {
         1.0f,  1.0f, -1.0f, 1.0f,  -1.0f, -1.0f, -1.0f, 1.0f, -1.0f,
         -1.0f, 1.0f, -1.0f, -1.0f, -1.0f, 1.0f,  -1.0f, 1.0f, 1.0f,
     };
     glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
     glEnableVertexAttribArray(position_loc);
     glVertexAttribPointer(position_loc, 2, GL_FLOAT, GL_FALSE, 0, 0);

     // Create a sample buffer.
     GLsizei num_samples = 4, max_samples = 0;
     glGetIntegerv(GL_MAX_SAMPLES, &max_samples);
     num_samples = std::min(num_samples, max_samples);
     GLuint sample_rb;
     glGenRenderbuffers(1, &sample_rb);
     glBindRenderbuffer(GL_RENDERBUFFER, sample_rb);
     glRenderbufferStorageMultisampleCHROMIUM(GL_RENDERBUFFER, num_samples,
                                              GL_RGBA8_OES, kWidth, kHeight);
     GLint param = 0;
     glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_SAMPLES,
                                  &param);
     EXPECT_GE(param, num_samples);

     glGenFramebuffers(1, &sample_fbo_);
     glBindFramebuffer(GL_FRAMEBUFFER, sample_fbo_);
     glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
                               GL_RENDERBUFFER, sample_rb);
     EXPECT_EQ(static_cast<GLenum>(GL_FRAMEBUFFER_COMPLETE),
               glCheckFramebufferStatus(GL_FRAMEBUFFER));
     glBindFramebuffer(GL_FRAMEBUFFER, 0);

     // Create another FBO to resolve the multisample buffer into.
     GLuint resolve_tex;
     glGenTextures(1, &resolve_tex);
     glBindTexture(GL_TEXTURE_2D, resolve_tex);
     glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, kWidth, kHeight, 0, GL_RGBA,
                  GL_UNSIGNED_BYTE, nullptr);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
     glGenFramebuffers(1, &resolve_fbo_);
     glBindFramebuffer(GL_FRAMEBUFFER, resolve_fbo_);
     glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D,
                            resolve_tex, 0);
     EXPECT_EQ(static_cast<GLenum>(GL_FRAMEBUFFER_COMPLETE),
               glCheckFramebufferStatus(GL_FRAMEBUFFER));

     glViewport(0, 0, kWidth, kHeight);
     glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
     glEnable(GL_BLEND);
     glBindFramebuffer(GL_FRAMEBUFFER, sample_fbo_);
     glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
     glClear(GL_COLOR_BUFFER_BIT);
   }

   void PrepareForVerify() {
     // Resolve.
     glBindFramebuffer(GL_READ_FRAMEBUFFER, sample_fbo_);
     glBindFramebuffer(GL_DRAW_FRAMEBUFFER, resolve_fbo_);
     glClearColor(1.0f, 0.0f, 0.0f, 0.0f);
     glClear(GL_COLOR_BUFFER_BIT);
     glBlitFramebufferCHROMIUM(0, 0, kWidth, kHeight, 0, 0, kWidth, kHeight,
                               GL_COLOR_BUFFER_BIT, GL_NEAREST);
     glBindFramebuffer(GL_READ_FRAMEBUFFER, resolve_fbo_);
   }

   bool IsApplicable() const {
     return GLTestHelper::HasExtension("GL_EXT_multisample_compatibility") &&
            GLTestHelper::HasExtension("GL_CHROMIUM_framebuffer_multisample") &&
            GLTestHelper::HasExtension("GL_OES_rgb8_rgba8") &&
            !GPUTestBotConfig::CurrentConfigMatches("AMD");
   }
   GLuint sample_fbo_;
   GLuint resolve_fbo_;
   GLuint color_loc_;

   GLManager gl_;
 };

 TEST_F(EXTMultisampleCompatibilityTest, TestSimple) {
   if (!IsApplicable()) {
     return;
   }

   EXPECT_TRUE(glIsEnabled(GL_MULTISAMPLE_EXT));
   glDisable(GL_MULTISAMPLE_EXT);
   EXPECT_FALSE(glIsEnabled(GL_MULTISAMPLE_EXT));
   glEnable(GL_MULTISAMPLE_EXT);
   EXPECT_TRUE(glIsEnabled(GL_MULTISAMPLE_EXT));

   EXPECT_FALSE(glIsEnabled(GL_SAMPLE_ALPHA_TO_ONE_EXT));
   glEnable(GL_SAMPLE_ALPHA_TO_ONE_EXT);
   EXPECT_TRUE(glIsEnabled(GL_SAMPLE_ALPHA_TO_ONE_EXT));
   glDisable(GL_SAMPLE_ALPHA_TO_ONE_EXT);
   EXPECT_FALSE(glIsEnabled(GL_SAMPLE_ALPHA_TO_ONE_EXT));

   EXPECT_EQ(static_cast<GLenum>(GL_NO_ERROR), glGetError());
 }

 TEST_F(EXTMultisampleCompatibilityTest, DrawAndResolve) {
   // Test that disabling GL_MULTISAMPLE_EXT is handled correctly.
   if (!IsApplicable()) {
     return;
   }

   static const float kBlue[] = {0.0f, 0.0f, 1.0f, 1.0f};
   static const float kGreen[] = {0.0f, 1.0f, 0.0f, 1.0f};
   static const float kRed[] = {1.0f, 0.0f, 0.0f, 1.0f};

   // Different drivers seem to behave differently with respect to resulting
   // values. These might be due to different MSAA sample counts causing
   // different samples to hit.  Other option is driver bugs. Just test that
   // disabling multisample causes a difference.
   std::unique_ptr<uint8_t[]> results[3];
   const GLint kResultSize = kWidth * kHeight * 4;
   for (int pass = 0; pass < 3; pass++) {
     PrepareForDraw();
     // Green: from top right to bottom left.
     glUniform4fv(color_loc_, 1, kGreen);
     glDrawArrays(GL_TRIANGLES, 0, 3);

     // Blue: from top left to bottom right.
     glUniform4fv(color_loc_, 1, kBlue);
     glDrawArrays(GL_TRIANGLES, 3, 3);

     // Red, with and without MSAA: from bottom left to top right.
     if (pass == 1) {
       glDisable(GL_MULTISAMPLE_EXT);
     }
     glUniform4fv(color_loc_, 1, kRed);
     glDrawArrays(GL_TRIANGLES, 6, 3);
     if (pass == 1) {
       glEnable(GL_MULTISAMPLE_EXT);
     }
     PrepareForVerify();
     results[pass].reset(new uint8_t[kResultSize]);
     memset(results[pass].get(), GLTestHelper::kCheckClearValue, kResultSize);
     glReadPixels(0, 0, kWidth, kHeight, GL_RGBA, GL_UNSIGNED_BYTE,
                  results[pass].get());
   }
   EXPECT_NE(0, memcmp(results[0].get(), results[1].get(), kResultSize));
   // Verify that rendering is deterministic, so that the pass above does not
   // come from non-deterministic rendering.
   EXPECT_EQ(0, memcmp(results[0].get(), results[2].get(), kResultSize));
 }

 TEST_F(EXTMultisampleCompatibilityTest, DrawAlphaOneAndResolve) {
   // Test that enabling GL_SAMPLE_ALPHA_TO_ONE_EXT affects rendering.
   if (!IsApplicable()) {
     return;
   }

 #if defined(OS_ANDROID)
   // TODO: Figure out why this fails on NVIDIA Shield. crbug.com/700060.
   std::string renderer(gl_.context()->GetGLRenderer());
   std::string version(gl_.context()->GetGLVersion());
   if (renderer.find("NVIDIA Tegra") != std::string::npos &&
       version.find("OpenGL ES 3.2 NVIDIA 361.00") != std::string::npos)
     return;
 #endif

   // SAMPLE_ALPHA_TO_ONE is specified to transform alpha values of
   // covered samples to 1.0. In order to detect it, we use non-1.0
   // alpha.
   static const float kBlue[] = {0.0f, 0.0f, 1.0f, 0.5f};
   static const float kGreen[] = {0.0f, 1.0f, 0.0f, 0.5f};
   static const float kRed[] = {1.0f, 0.0f, 0.0f, 0.5f};

   // Different drivers seem to behave differently with respect to resulting
   // alpha value. These might be due to different MSAA sample counts causing
   // different samples to hit.  Other option is driver bugs. Testing exact or
   // even approximate sample values is not that easy.  Thus, just test
   // representative positions which have fractional pixels, inspecting that
   // normal rendering is different to SAMPLE_ALPHA_TO_ONE rendering.
   std::unique_ptr<uint8_t[]> results[3];
   const GLint kResultSize = kWidth * kHeight * 4;

   for (int pass = 0; pass < 3; ++pass) {
     PrepareForDraw();
     if (pass == 1) {
       glEnable(GL_SAMPLE_ALPHA_TO_ONE_EXT);
     }
     glEnable(GL_MULTISAMPLE_EXT);
     glUniform4fv(color_loc_, 1, kGreen);
     glDrawArrays(GL_TRIANGLES, 0, 3);

     glUniform4fv(color_loc_, 1, kBlue);
     glDrawArrays(GL_TRIANGLES, 3, 3);

     glDisable(GL_MULTISAMPLE_EXT);
     glUniform4fv(color_loc_, 1, kRed);
     glDrawArrays(GL_TRIANGLES, 6, 3);

     PrepareForVerify();
     results[pass].reset(new uint8_t[kResultSize]);
     memset(results[pass].get(), GLTestHelper::kCheckClearValue, kResultSize);
     glReadPixels(0, 0, kWidth, kHeight, GL_RGBA, GL_UNSIGNED_BYTE,
                  results[pass].get());
     if (pass == 1) {
       glDisable(GL_SAMPLE_ALPHA_TO_ONE_EXT);
     }
   }
   EXPECT_NE(0, memcmp(results[0].get(), results[1].get(), kResultSize));
   // Verify that rendering is deterministic, so that the pass above does not
   // come from non-deterministic rendering.
   EXPECT_EQ(0, memcmp(results[0].get(), results[2].get(), kResultSize));
 }

 }  // namespace gpu
	// Copyright (c) 2015 The Chromium Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	#include <GLES2/gl2.h>
	#include <GLES2/gl2ext.h>
	#include <GLES2/gl2extchromium.h>
	#include <stdint.h>

	#include <memory>

	#include "gpu/command_buffer/tests/gl_manager.h"
	#include "gpu/command_buffer/tests/gl_test_utils.h"
	#include "gpu/config/gpu_test_config.h"
	#include "testing/gtest/include/gtest/gtest.h"
	#include "ui/gl/gl_context.h"

	#define SHADER0(Src) #Src

	namespace gpu {

	class EXTMultisampleCompatibilityTest : public testing::Test {
	public:
	protected:
	static const GLuint kWidth = 100;
	static const GLuint kHeight = 100;

	void SetUp() override { gl_.Initialize(GLManager::Options()); }

	void TearDown() override { gl_.Destroy(); }

	void PrepareForDraw() {
	static const char* v_shader_str = SHADER0(
	attribute vec4 a_Position; void main() { gl_Position = a_Position; });
	static const char* f_shader_str =
	SHADER0(precision mediump float; uniform vec4 color;
	void main() { gl_FragColor = color; });

	GLuint program = GLTestHelper::LoadProgram(v_shader_str, f_shader_str);
	glUseProgram(program);
	GLuint position_loc = glGetAttribLocation(program, "a_Position");
	color_loc_ = glGetUniformLocation(program, "color");

	GLuint vbo = 0;
	glGenBuffers(1, &vbo);
	glBindBuffer(GL_ARRAY_BUFFER, vbo);
	static float vertices[] = {
	1.0f, 1.0f, -1.0f, 1.0f, -1.0f, -1.0f, -1.0f, 1.0f, -1.0f,
	-1.0f, 1.0f, -1.0f, -1.0f, -1.0f, 1.0f, -1.0f, 1.0f, 1.0f,
	};
	glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
	glEnableVertexAttribArray(position_loc);
	glVertexAttribPointer(position_loc, 2, GL_FLOAT, GL_FALSE, 0, 0);

	// Create a sample buffer.
	GLsizei num_samples = 4, max_samples = 0;
	glGetIntegerv(GL_MAX_SAMPLES, &max_samples);
	num_samples = std::min(num_samples, max_samples);
	GLuint sample_rb;
	glGenRenderbuffers(1, &sample_rb);
	glBindRenderbuffer(GL_RENDERBUFFER, sample_rb);
	glRenderbufferStorageMultisampleCHROMIUM(GL_RENDERBUFFER, num_samples,
	GL_RGBA8_OES, kWidth, kHeight);
	GLint param = 0;
	glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_SAMPLES,
	&param);
	EXPECT_GE(param, num_samples);

	glGenFramebuffers(1, &sample_fbo_);
	glBindFramebuffer(GL_FRAMEBUFFER, sample_fbo_);
	glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
	GL_RENDERBUFFER, sample_rb);
	EXPECT_EQ(static_cast<GLenum>(GL_FRAMEBUFFER_COMPLETE),
	glCheckFramebufferStatus(GL_FRAMEBUFFER));
	glBindFramebuffer(GL_FRAMEBUFFER, 0);

	// Create another FBO to resolve the multisample buffer into.
	GLuint resolve_tex;
	glGenTextures(1, &resolve_tex);
	glBindTexture(GL_TEXTURE_2D, resolve_tex);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, kWidth, kHeight, 0, GL_RGBA,
	GL_UNSIGNED_BYTE, nullptr);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
	glGenFramebuffers(1, &resolve_fbo_);
	glBindFramebuffer(GL_FRAMEBUFFER, resolve_fbo_);
	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D,
	resolve_tex, 0);
	EXPECT_EQ(static_cast<GLenum>(GL_FRAMEBUFFER_COMPLETE),
	glCheckFramebufferStatus(GL_FRAMEBUFFER));

	glViewport(0, 0, kWidth, kHeight);
	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
	glEnable(GL_BLEND);
	glBindFramebuffer(GL_FRAMEBUFFER, sample_fbo_);
	glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
	glClear(GL_COLOR_BUFFER_BIT);
	}

	void PrepareForVerify() {
	// Resolve.
	glBindFramebuffer(GL_READ_FRAMEBUFFER, sample_fbo_);
	glBindFramebuffer(GL_DRAW_FRAMEBUFFER, resolve_fbo_);
	glClearColor(1.0f, 0.0f, 0.0f, 0.0f);
	glClear(GL_COLOR_BUFFER_BIT);
	glBlitFramebufferCHROMIUM(0, 0, kWidth, kHeight, 0, 0, kWidth, kHeight,
	GL_COLOR_BUFFER_BIT, GL_NEAREST);
	glBindFramebuffer(GL_READ_FRAMEBUFFER, resolve_fbo_);
	}

	bool IsApplicable() const {
	return GLTestHelper::HasExtension("GL_EXT_multisample_compatibility") &&
	GLTestHelper::HasExtension("GL_CHROMIUM_framebuffer_multisample") &&
	GLTestHelper::HasExtension("GL_OES_rgb8_rgba8") &&
	!GPUTestBotConfig::CurrentConfigMatches("AMD");
	}
	GLuint sample_fbo_;
	GLuint resolve_fbo_;
	GLuint color_loc_;

	GLManager gl_;
	};

	TEST_F(EXTMultisampleCompatibilityTest, TestSimple) {
	if (!IsApplicable()) {
	return;
	}

	EXPECT_TRUE(glIsEnabled(GL_MULTISAMPLE_EXT));
	glDisable(GL_MULTISAMPLE_EXT);
	EXPECT_FALSE(glIsEnabled(GL_MULTISAMPLE_EXT));
	glEnable(GL_MULTISAMPLE_EXT);
	EXPECT_TRUE(glIsEnabled(GL_MULTISAMPLE_EXT));

	EXPECT_FALSE(glIsEnabled(GL_SAMPLE_ALPHA_TO_ONE_EXT));
	glEnable(GL_SAMPLE_ALPHA_TO_ONE_EXT);
	EXPECT_TRUE(glIsEnabled(GL_SAMPLE_ALPHA_TO_ONE_EXT));
	glDisable(GL_SAMPLE_ALPHA_TO_ONE_EXT);
	EXPECT_FALSE(glIsEnabled(GL_SAMPLE_ALPHA_TO_ONE_EXT));

	EXPECT_EQ(static_cast<GLenum>(GL_NO_ERROR), glGetError());
	}

	TEST_F(EXTMultisampleCompatibilityTest, DrawAndResolve) {
	// Test that disabling GL_MULTISAMPLE_EXT is handled correctly.
	if (!IsApplicable()) {
	return;
	}

	static const float kBlue[] = {0.0f, 0.0f, 1.0f, 1.0f};
	static const float kGreen[] = {0.0f, 1.0f, 0.0f, 1.0f};
	static const float kRed[] = {1.0f, 0.0f, 0.0f, 1.0f};

	// Different drivers seem to behave differently with respect to resulting
	// values. These might be due to different MSAA sample counts causing
	// different samples to hit. Other option is driver bugs. Just test that
	// disabling multisample causes a difference.
	std::unique_ptr<uint8_t[]> results[3];
	const GLint kResultSize = kWidth * kHeight * 4;
	for (int pass = 0; pass < 3; pass++) {
	PrepareForDraw();
	// Green: from top right to bottom left.
	glUniform4fv(color_loc_, 1, kGreen);
	glDrawArrays(GL_TRIANGLES, 0, 3);

	// Blue: from top left to bottom right.
	glUniform4fv(color_loc_, 1, kBlue);
	glDrawArrays(GL_TRIANGLES, 3, 3);

	// Red, with and without MSAA: from bottom left to top right.
	if (pass == 1) {
	glDisable(GL_MULTISAMPLE_EXT);
	}
	glUniform4fv(color_loc_, 1, kRed);
	glDrawArrays(GL_TRIANGLES, 6, 3);
	if (pass == 1) {
	glEnable(GL_MULTISAMPLE_EXT);
	}
	PrepareForVerify();
	results[pass].reset(new uint8_t[kResultSize]);
	memset(results[pass].get(), GLTestHelper::kCheckClearValue, kResultSize);
	glReadPixels(0, 0, kWidth, kHeight, GL_RGBA, GL_UNSIGNED_BYTE,
	results[pass].get());
	}
	EXPECT_NE(0, memcmp(results[0].get(), results[1].get(), kResultSize));
	// Verify that rendering is deterministic, so that the pass above does not
	// come from non-deterministic rendering.
	EXPECT_EQ(0, memcmp(results[0].get(), results[2].get(), kResultSize));
	}

	TEST_F(EXTMultisampleCompatibilityTest, DrawAlphaOneAndResolve) {
	// Test that enabling GL_SAMPLE_ALPHA_TO_ONE_EXT affects rendering.
	if (!IsApplicable()) {
	return;
	}

	#if defined(OS_ANDROID)
	// TODO: Figure out why this fails on NVIDIA Shield. crbug.com/700060.
	std::string renderer(gl_.context()->GetGLRenderer());
	std::string version(gl_.context()->GetGLVersion());
	if (renderer.find("NVIDIA Tegra") != std::string::npos &&
	version.find("OpenGL ES 3.2 NVIDIA 361.00") != std::string::npos)
	return;
	#endif

	// SAMPLE_ALPHA_TO_ONE is specified to transform alpha values of
	// covered samples to 1.0. In order to detect it, we use non-1.0
	// alpha.
	static const float kBlue[] = {0.0f, 0.0f, 1.0f, 0.5f};
	static const float kGreen[] = {0.0f, 1.0f, 0.0f, 0.5f};
	static const float kRed[] = {1.0f, 0.0f, 0.0f, 0.5f};

	// Different drivers seem to behave differently with respect to resulting
	// alpha value. These might be due to different MSAA sample counts causing
	// different samples to hit. Other option is driver bugs. Testing exact or
	// even approximate sample values is not that easy. Thus, just test
	// representative positions which have fractional pixels, inspecting that
	// normal rendering is different to SAMPLE_ALPHA_TO_ONE rendering.
	std::unique_ptr<uint8_t[]> results[3];
	const GLint kResultSize = kWidth * kHeight * 4;

	for (int pass = 0; pass < 3; ++pass) {
	PrepareForDraw();
	if (pass == 1) {
	glEnable(GL_SAMPLE_ALPHA_TO_ONE_EXT);
	}
	glEnable(GL_MULTISAMPLE_EXT);
	glUniform4fv(color_loc_, 1, kGreen);
	glDrawArrays(GL_TRIANGLES, 0, 3);

	glUniform4fv(color_loc_, 1, kBlue);
	glDrawArrays(GL_TRIANGLES, 3, 3);

	glDisable(GL_MULTISAMPLE_EXT);
	glUniform4fv(color_loc_, 1, kRed);
	glDrawArrays(GL_TRIANGLES, 6, 3);

	PrepareForVerify();
	results[pass].reset(new uint8_t[kResultSize]);
	memset(results[pass].get(), GLTestHelper::kCheckClearValue, kResultSize);
	glReadPixels(0, 0, kWidth, kHeight, GL_RGBA, GL_UNSIGNED_BYTE,
	results[pass].get());
	if (pass == 1) {
	glDisable(GL_SAMPLE_ALPHA_TO_ONE_EXT);
	}
	}
	EXPECT_NE(0, memcmp(results[0].get(), results[1].get(), kResultSize));
	// Verify that rendering is deterministic, so that the pass above does not
	// come from non-deterministic rendering.
	EXPECT_EQ(0, memcmp(results[0].get(), results[2].get(), kResultSize));
	}

	} // namespace gpu