gpu, cmaa: copy RGBA8 texture via glCopyTexSubImage2D() instead of imageStore().

gpu/command_buffer/service/gles2_cmd_apply_framebuffer_attachment_cmaa_intel.cc

 // Copyright 2016 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 "gpu/command_buffer/service/gles2_cmd_apply_framebuffer_attachment_cmaa_intel.h"
 
 #include "base/logging.h"
 #include "gpu/command_buffer/service/framebuffer_manager.h"
 #include "gpu/command_buffer/service/gles2_cmd_decoder.h"
 #include "ui/gl/gl_context.h"
@@ skipping 11 matching lines @@
       textures_initialized_(false),
       is_in_gamma_correct_mode_(false),
       supports_usampler_(true),
       supports_r8_image_(true),
       supports_r8_read_format_(true),
       is_gles31_compatible_(false),
       frame_id_(0),
       width_(0),
       height_(0),
       copy_to_framebuffer_shader_(0),
-      copy_to_image_shader_(0),
       edges0_shader_(0),
       edges1_shader_(0),
       edges_combine_shader_(0),
       process_and_apply_shader_(0),
       debug_display_edges_shader_(0),
       cmaa_framebuffer_(0),
       copy_framebuffer_(0),
       rgba8_texture_(0),
       working_color_texture_(0),
       edges0_texture_(0),
       edges1_texture_(0),
       mini4_edge_texture_(0),
       mini4_edge_depth_texture_(0),
       edges1_shader_result_texture_float4_slot1_(0),
       edges1_shader_result_texture_(0),
       edges_combine_shader_result_texture_float4_slot1_(0),
       process_and_apply_shader_result_texture_float4_slot1_(0),
-      edges_combine_shader_result_texture_slot2_(0),
-      copy_to_image_shader_outTexture_(0) {}
+      edges_combine_shader_result_texture_slot2_(0) {}
 
 ApplyFramebufferAttachmentCMAAINTELResourceManager::
     ~ApplyFramebufferAttachmentCMAAINTELResourceManager() {
   Destroy();
 }
 
 void ApplyFramebufferAttachmentCMAAINTELResourceManager::Initialize(
     gles2::GLES2Decoder* decoder) {
   DCHECK(decoder);
   is_gles31_compatible_ =
       decoder->GetGLContext()->GetVersionInfo()->IsAtLeastGLES(3, 1);
 
-  copy_to_image_shader_ = CreateProgram("", vert_str_, copy_frag_str_);
-  copy_to_framebuffer_shader_ =
-      CreateProgram("#define OUT_FBO 1\n", vert_str_, copy_frag_str_);
+  copy_to_framebuffer_shader_ = CreateProgram("", vert_str_, copy_frag_str_);
 
   // Check if RGBA8UI is supported as an FBO colour target with depth.
   // If not supported, GLSL needs to convert the data to/from float so there is
   // a small extra cost.
   {
     GLuint rgba8ui_texture = 0, depth_texture = 0;
     glGenTextures(1, &rgba8ui_texture);
     glBindTexture(GL_TEXTURE_2D, rgba8ui_texture);
     glTexStorage2DEXT(GL_TEXTURE_2D, 1, GL_RGBA8UI, 4, 4);
 
@@ skipping 106 matching lines @@
   edges1_shader_result_texture_float4_slot1_ =
       glGetUniformLocation(edges0_shader_, "g_resultTextureFlt4Slot1");
   edges1_shader_result_texture_ =
       glGetUniformLocation(edges1_shader_, "g_resultTexture");
   edges_combine_shader_result_texture_float4_slot1_ =
       glGetUniformLocation(edges_combine_shader_, "g_resultTextureFlt4Slot1");
   edges_combine_shader_result_texture_slot2_ =
       glGetUniformLocation(edges_combine_shader_, "g_resultTextureSlot2");
   process_and_apply_shader_result_texture_float4_slot1_ = glGetUniformLocation(
       process_and_apply_shader_, "g_resultTextureFlt4Slot1");
-  copy_to_image_shader_outTexture_ =
-      glGetUniformLocation(copy_to_image_shader_, "outTexture");
 
   initialized_ = true;
 }
 
 void ApplyFramebufferAttachmentCMAAINTELResourceManager::Destroy() {
   if (!initialized_)
     return;
 
   ReleaseTextures();
 
-  glDeleteProgram(copy_to_image_shader_);
   glDeleteProgram(copy_to_framebuffer_shader_);
   glDeleteProgram(process_and_apply_shader_);
   glDeleteProgram(edges_combine_shader_);
   glDeleteProgram(edges1_shader_);
   glDeleteProgram(edges0_shader_);
   glDeleteProgram(debug_display_edges_shader_);
 
   initialized_ = false;
 }
 
 // Apply CMAA(Conservative Morphological Anti-Aliasing) algorithm to the
 // color attachments of currently bound draw framebuffer.
 // Reference GL_INTEL_framebuffer_CMAA for details.
 void ApplyFramebufferAttachmentCMAAINTELResourceManager::
     ApplyFramebufferAttachmentCMAAINTEL(gles2::GLES2Decoder* decoder,
                                         gles2::Framebuffer* framebuffer) {
   DCHECK(decoder);
   DCHECK(initialized_);
   if (!framebuffer)
     return;
 
+  glDisable(GL_SCISSOR_TEST);
+  glDisable(GL_STENCIL_TEST);
+  glDisable(GL_CULL_FACE);
+  glDisable(GL_BLEND);

[dshwang, 2016/09/02 15:00:21]

These was in CopyTexture(), but ApplyCMAAEffectTexture() also needs them. so
move it here. It is not related to this CL anyway.

+
   GLuint last_framebuffer = framebuffer->service_id();
 
   // Process each color attachment of the current draw framebuffer.
   uint32_t max_draw_buffers = decoder->GetContextGroup()->max_draw_buffers();
   for (uint32_t i = 0; i < max_draw_buffers; i++) {
     const gles2::Framebuffer::Attachment* attachment =
         framebuffer->GetAttachment(GL_COLOR_ATTACHMENT0 + i);
     if (attachment && attachment->IsTextureAttachment()) {
       // Get the texture info.
       GLuint source_texture_client_id = attachment->object_name();
       GLuint source_texture = 0;
       if (!decoder->GetServiceTextureId(source_texture_client_id,
                                         &source_texture))
         continue;
       GLsizei width = attachment->width();
       GLsizei height = attachment->height();
       GLenum internal_format = attachment->internal_format();
 
       // Resize internal structures - only if needed.
       OnSize(width, height);
 
       // CMAA internally expects GL_RGBA8 textures.
       // Process using a GL_RGBA8 copy if this is not the case.
       bool do_copy = internal_format != GL_RGBA8;
 
       // Copy source_texture to rgba8_texture_
       if (do_copy) {
-        CopyTexture(source_texture, rgba8_texture_, false);
+        glBindFramebufferEXT(GL_FRAMEBUFFER, copy_framebuffer_);
+        glFramebufferTexture2DEXT(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
+                                  GL_TEXTURE_2D, rgba8_texture_, 0);
+        CopyTexture(source_texture);
       }
 
       // CMAA Effect
-      glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, last_framebuffer);
       if (do_copy) {
         ApplyCMAAEffectTexture(rgba8_texture_, rgba8_texture_);
       } else {
         ApplyCMAAEffectTexture(source_texture, source_texture);
       }
 
       // Copy rgba8_texture_ to source_texture
       if (do_copy) {
         // Move source_texture to the first color attachment of the copy fbo.
         glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, last_framebuffer);
         glFramebufferTexture2DEXT(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0 + i,
                                   GL_TEXTURE_2D, 0, 0);
         glBindFramebufferEXT(GL_FRAMEBUFFER, copy_framebuffer_);
         glFramebufferTexture2DEXT(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
                                   GL_TEXTURE_2D, source_texture, 0);
 
-        CopyTexture(rgba8_texture_, source_texture, true);
+        CopyTexture(rgba8_texture_);
 
         // Restore color attachments
         glBindFramebufferEXT(GL_FRAMEBUFFER, copy_framebuffer_);
         glFramebufferTexture2DEXT(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
                                   GL_TEXTURE_2D, rgba8_texture_, 0);
         glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, last_framebuffer);
         glFramebufferTexture2DEXT(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0 + i,
                                   GL_TEXTURE_2D, source_texture, 0);
       }
     }
@@ skipping 272 matching lines @@
     glDeleteTextures(1, &edges0_texture_);
     glDeleteTextures(1, &edges1_texture_);
     glDeleteTextures(1, &mini4_edge_texture_);
     glDeleteTextures(1, &mini4_edge_depth_texture_);
     glDeleteTextures(1, &working_color_texture_);
   }
   textures_initialized_ = false;
 }
 
 void ApplyFramebufferAttachmentCMAAINTELResourceManager::CopyTexture(
-    GLint source,
-    GLint dest,
-    bool via_fbo) {
+    GLint source) {
   glViewport(0, 0, width_, height_);
   glActiveTexture(GL_TEXTURE0);
   glBindTexture(GL_TEXTURE_2D, source);
 
-  if (!via_fbo) {
-    glUseProgram(copy_to_image_shader_);
-    if (!is_gles31_compatible_) {
-      glUniform1i(copy_to_image_shader_outTexture_, 0);
-    }
-    glBindImageTextureEXT(0, dest, 0, GL_FALSE, 0, GL_WRITE_ONLY, GL_RGBA8);
-  } else {
-    glDisable(GL_DEPTH_TEST);
-    glDisable(GL_STENCIL_TEST);
-    glDisable(GL_CULL_FACE);
-    glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
-    glDepthMask(GL_FALSE);
-    glDisable(GL_BLEND);
-    glUseProgram(copy_to_framebuffer_shader_);
-  }
+  glDisable(GL_DEPTH_TEST);
+  glDepthMask(GL_FALSE);
+  glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
+  glUseProgram(copy_to_framebuffer_shader_);
 
   glDrawArrays(GL_TRIANGLES, 0, 3);
   glUseProgram(0);
   glBindTexture(GL_TEXTURE_2D, 0);
 }
 
 GLuint ApplyFramebufferAttachmentCMAAINTELResourceManager::CreateProgram(
     const char* defines,
     const char* vs_source,
     const char* fs_source) {
@@ skipping 1282 matching lines @@
     \n#endif\n
     }
   );
 
 const char
   ApplyFramebufferAttachmentCMAAINTELResourceManager::copy_frag_str_[] =
     SHADER(
       precision highp float;
       layout(binding = 0) uniform highp sampler2D inTexture;
       layout(location = 0) out vec4 outColor;
-      \n#ifdef GL_ES\n
-      layout(binding = 0, rgba8) restrict writeonly uniform highp
-                                                     image2D outTexture;
-      \n#else\n
-      layout(rgba8) restrict writeonly uniform highp image2D outTexture;
-      \n#endif\n
 
       void main() {
         ivec2 screenPosI = ivec2( gl_FragCoord.xy );
         vec4 pixel = texelFetch(inTexture, screenPosI, 0);
-      \n#ifdef OUT_FBO\n
         outColor = pixel;
-      \n#else\n
-        imageStore(outTexture, screenPosI, pixel);

[dshwang, 2016/09/02 15:00:21]

simple fix is adding following line here.
  outColor = vec4(0.);
However, this solution make this code and later CMAA phase entangled. vec4(0.)
hack requires the knowledge of implementation detail of next phase. So I remove
whole imageStore() path.

adrian@, jon@, do you have specific reason to prefer imageStore() to FBO write.
In my opinion, it's not necessary. RGBA8 to RGBA8 copy works well with FBO
write. In addition, ApplyCMAAEffectTexture() already writes something on RGBA8
and R8 FBO.

-      \n#endif\n
       }
     );
 /* clang-format on */
 
 }  // namespace gles2
 }  // namespace gpu