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..4ade1e411047b96946146fdcedf43b2b24bdbdbe 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 +47,115 @@ 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);
+  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));
+
+  // 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(width / 4, (3 * height) / 4, 1, 1, 0, green));
+  EXPECT_TRUE(GLTestHelper::CheckPixels(width - 1, 0, 1, 1, 0, black));
+}
+
 }  // namespace gpu