Add a basic test for GL_CHROMIUM_framebuffer_multisample

gpu/command_buffer/tests/gl_chromium_framebuffer_multisample_unittest.cc

 // Copyright (c) 2012 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 "gpu/command_buffer/tests/gl_manager.h"
 #include "gpu/command_buffer/tests/gl_test_utils.h"
@@ skipping 29 matching lines @@
   // If the caching is bad the second call to glBindFramebuffer will do nothing.
   // which means the draw buffer is bad and will not return
   // GL_FRAMEBUFFER_COMPLETE and rendering will generate an error.
   EXPECT_EQ(static_cast<GLenum>(GL_FRAMEBUFFER_COMPLETE),
             glCheckFramebufferStatus(GL_FRAMEBUFFER));
 
   glClear(GL_COLOR_BUFFER_BIT);
   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