Add a basic test for GL_CHROMIUM_framebuffer_multisample

gpu/command_buffer/tests/gl_chromium_framebuffer_multisample_unittest.cc

Index: gpu/command_buffer/tests/gl_chromium_framebuffer_multisample_unittest.cc
diff --git a/gpu/command_buffer/tests/gl_chromium_framebuffer_multisample_unittest.cc b/gpu/command_buffer/tests/gl_chromium_framebuffer_multisample_unittest.cc
index c1d3c9885c6a8e1da9a9ea78086ec546066fe88a..95fc84313e5de5cd2c3ace11bdc67a3935c80b87 100644
--- a/gpu/command_buffer/tests/gl_chromium_framebuffer_multisample_unittest.cc
+++ b/gpu/command_buffer/tests/gl_chromium_framebuffer_multisample_unittest.cc
@@ -47,5 +47,114 @@ TEST_F(GLChromiumFramebufferMultisampleTest, CachedBindingsTest) {
   GLTestHelper::CheckGLError("no errors", __LINE__);
 }
 
+TEST_F(GLChromiumFramebufferMultisampleTest, DrawAndResolve) {
+  if (!GLTestHelper::HasExtension("GL_CHROMIUM_framebuffer_multisample")) {
+    return;
+  }
+
+  static const char* v_shader_str =
+      "attribute vec4 a_Position;\n"
+      "void main()\n"
+      "{\n"
+      "   gl_Position = a_Position;\n"
+      "}\n";
+  static const char* f_shader_str =
+      "precision mediump float;\n"
+      "void main()\n"
+      "{\n"
+      "  gl_FragColor = vec4(0.0, 1.0, 0.0, 1.0);\n"
+      "}\n";
+
+  GLuint program = GLTestHelper::LoadProgram(v_shader_str, f_shader_str);
+  glUseProgram(program);
+  GLuint position_loc = glGetAttribLocation(program, "a_Position");
+
+  GLTestHelper::SetupUnitQuad(position_loc);
+
+  const GLuint width = 100;
+  const GLuint height = 100;
+
+  // 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_fbo, sample_rb;
+  glGenRenderbuffers(1, &sample_rb);
+  glBindRenderbuffer(GL_RENDERBUFFER, sample_rb);
+  glRenderbufferStorageMultisampleEXT(
+      GL_RENDERBUFFER, num_samples, GL_RGBA8_OES, width, height);
+  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));
+
+  // Create another FBO to resolve the multisample buffer into.
+  GLuint resolve_fbo, resolve_tex;
+  glGenTextures(1, &resolve_tex);
+  glBindTexture(GL_TEXTURE_2D, resolve_tex);
+  glTexImage2D(GL_TEXTURE_2D,
+               0,
+               GL_RGBA,
+               width,
+               height,
+               0,
+               GL_RGBA,
+               GL_UNSIGNED_BYTE,
+               NULL);
+  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

[Sami, 2013/10/29 16:31:16]

Pet peeve: glTexParameteri :)

[no sievers, 2013/10/29 18:45:48]

Done.

+  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+  glTexParameterf(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));
+
+  // Draw one triangle (bottom left half).
+  glViewport(0, 0, width, height);
+  glBindFramebuffer(GL_FRAMEBUFFER, sample_fbo);
+  glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
+  glClear(GL_COLOR_BUFFER_BIT);
+  glDrawArrays(GL_TRIANGLES, 0, 3);
+
+  // 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);
+  glBlitFramebufferEXT(0,
+                       0,
+                       width,
+                       height,
+                       0,
+                       0,
+                       width,
+                       height,
+                       GL_COLOR_BUFFER_BIT,
+                       GL_NEAREST);
+
+  // Verify.
+  const uint8 green[] = {0, 255, 0, 255};
+  const uint8 black[] = {0, 0, 0, 0};
+  glBindFramebuffer(GL_READ_FRAMEBUFFER, resolve_fbo);
+  EXPECT_TRUE(GLTestHelper::CheckPixels(0, height - 1, 1, 1, 0, green));

[Sami, 2013/10/29 16:31:16]

I wonder if this part could be a little flaky since you're checking at the very
corner of the viewport which is also at the edge of the triangle. Some MSAA
sample configuration could result in low order bit noise here. To be safer I'd
move these a little closer to the center.

[no sievers, 2013/10/29 18:45:48]

Done.

+  EXPECT_TRUE(GLTestHelper::CheckPixels(width - 1, 0, 1, 1, 0, black));
+}
+
 }  // namespace gpu