Support glCopyTex[Sub]Image to LUMA formats on the core profile.

gpu/command_buffer/service/gles2_cmd_copy_tex_image.cc

Index: gpu/command_buffer/service/gles2_cmd_copy_tex_image.cc
diff --git a/gpu/command_buffer/service/gles2_cmd_copy_tex_image.cc b/gpu/command_buffer/service/gles2_cmd_copy_tex_image.cc
new file mode 100644
index 0000000000000000000000000000000000000000..a5743ed4d97a79e3640725f3f46559d171864601
--- /dev/null
+++ b/gpu/command_buffer/service/gles2_cmd_copy_tex_image.cc
@@ -0,0 +1,262 @@
+// Copyright (c) 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_copy_tex_image.h"
+
+#include "gpu/command_buffer/service/texture_manager.h"
+#include "ui/gl/gl_version_info.h"
+
+namespace {
+
+void CompileShader(GLuint shader, const char* shader_source) {
+  glShaderSource(shader, 1, &shader_source, 0);
+  glCompileShader(shader);
+#ifndef NDEBUG
+  GLint compile_status;
+  glGetShaderiv(shader, GL_COMPILE_STATUS, &compile_status);
+  if (GL_TRUE != compile_status)
+    DLOG(ERROR) << "CopyTexImage: shader compilation failure.";
+#endif
+}
+
+}  // anonymous namespace
+
+namespace gpu {
+
+CopyTexImageResourceManager::CopyTexImageResourceManager(
+    const gles2::FeatureInfo* feature_info)
+    : feature_info_(feature_info) {
+  DCHECK(feature_info->gl_version_info().is_desktop_core_profile);
+}
+
+CopyTexImageResourceManager::~CopyTexImageResourceManager() {}
+
+void CopyTexImageResourceManager::Initialize(
+    const gles2::GLES2Decoder* decoder) {
+  if (initialized_) {
+    return;
+  }
+
+  blit_program_ = glCreateProgram();
+
+  // Compile the fragment shader
+  const char* vs_source =
+      "#version 150\n"
+      "out vec2 v_texcoord;\n"
+      "\n"
+      "void main()\n"
+      "{\n"
+      "    const vec2 quad_positions[6] = vec2[6]\n"
+      "    (\n"
+      "        vec2(0.0f, 0.0f),\n"
+      "        vec2(0.0f, 1.0f),\n"
+      "        vec2(1.0f, 0.0f),\n"
+      "\n"
+      "        vec2(0.0f, 1.0f),\n"
+      "        vec2(1.0f, 0.0f),\n"
+      "        vec2(1.0f, 1.0f)\n"
+      "    );\n"
+      "\n"
+      "    gl_Position = vec4((quad_positions[gl_VertexID] * 2.0) - 1.0, 0.0, "
+      "1.0);\n"
+      "    v_texcoord = quad_positions[gl_VertexID];\n"
+      "}\n";
+
+  GLuint vs = glCreateShader(GL_VERTEX_SHADER);
+  CompileShader(vs, vs_source);
+  glAttachShader(blit_program_, vs);
+  glDeleteShader(vs);
+
+  // Compile the vertex shader
+  const char* fs_source =
+      "#version 150\n"
+      "uniform sampler2D u_source_texture;\n"
+      "in vec2 v_texcoord;\n"
+      "out vec4 output_color;\n"
+      "\n"
+      "void main()\n"
+      "{\n"
+      "    output_color = texture(u_source_texture, v_texcoord);\n"
+      "}\n";
+
+  GLuint fs = glCreateShader(GL_FRAGMENT_SHADER);
+  CompileShader(fs, fs_source);
+  glAttachShader(blit_program_, fs);
+  glDeleteShader(fs);
+
+  glLinkProgram(blit_program_);
+#ifndef NDEBUG
+  GLint linked = 0;
+  glGetProgramiv(blit_program_, GL_LINK_STATUS, &linked);
+  if (!linked) {
+    DLOG(ERROR) << "CopyTexImage: program link failure.";
+  }
+#endif
+
+  GLuint textureUniform =

[Zhenyao Mo, 2016/06/01 18:24:18]

nit: texture_uniform.

[Geoff Lang, 2016/06/01 20:12:18]

Done.

+      glGetUniformLocation(blit_program_, "u_source_texture");
+  glUseProgram(blit_program_);
+  glUniform1i(textureUniform, 0);
+
+  glGenTextures(scratch_textures_.size(), scratch_textures_.data());
+  glActiveTexture(GL_TEXTURE0);

[Zhenyao Mo, 2016/06/01 18:24:18]

You don't care which active texture to use, so no need to set it to 0 here, and
no need to restore it later.

[Zhenyao Mo, 2016/06/01 18:26:48]

Never mind, it's easier this way for RestoreTextureUnitBindings.

+  for (auto scratch_texture : scratch_textures_) {
+    glBindTexture(GL_TEXTURE_2D, scratch_texture);
+
+    // Use nearest, non-mipmapped sampling with the scratch texture
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+  }
+
+  glGenFramebuffersEXT(1, &scratch_fbo_);
+  glGenVertexArraysOES(1, &vao_);
+
+  decoder->RestoreTextureUnitBindings(0);
+  decoder->RestoreActiveTexture();
+  decoder->RestoreProgramBindings();
+
+  initialized_ = true;
+}
+
+void CopyTexImageResourceManager::Destroy() {
+  if (!initialized_) {
+    return;
+  }
+
+  glDeleteProgram(blit_program_);
+  glDeleteTextures(scratch_textures_.size(), scratch_textures_.data());
+  glDeleteFramebuffersEXT(1, &scratch_fbo_);
+  glDeleteVertexArraysOES(1, &vao_);

[Zhenyao Mo, 2016/06/01 18:26:48]

Although you don't intend it to be re-initialized again after destroy, but it's
better to be safer to set all these variables to 0 after deletion.

[Geoff Lang, 2016/06/01 20:12:18]

Done.

+
+  initialized_ = false;
+}
+
+void CopyTexImageResourceManager::DoCopyTexImage2DToLUMAComatabilityTexture(
+    const gles2::GLES2Decoder* decoder,
+    GLuint dest_texture,
+    GLenum dest_texture_target,
+    GLenum dest_target,
+    GLenum luma_format,
+    GLenum luma_type,
+    GLint level,
+    GLenum internal_format,
+    GLint x,
+    GLint y,
+    GLsizei width,
+    GLsizei height,
+    GLuint source_framebuffer,
+    GLenum source_framebuffer_internal_format) {
+  GLenum adjusted_internal_format =
+      gles2::TextureManager::AdjustTexInternalFormat(feature_info_.get(),
+                                                     internal_format);
+  GLenum adjusted_format = gles2::TextureManager::AdjustTexFormat(
+      feature_info_.get(), internal_format);
+  glTexImage2D(dest_target, level, adjusted_internal_format, width, height, 0,
+               adjusted_format, luma_type, nullptr);
+  DoCopyTexSubImage2DToLUMAComatabilityTexture(
+      decoder, dest_texture, dest_texture_target, dest_target, luma_format,
+      luma_type, level, 0, 0, x, y, width, height, source_framebuffer,
+      source_framebuffer_internal_format);
+}
+
+void CopyTexImageResourceManager::DoCopyTexSubImage2DToLUMAComatabilityTexture(
+    const gles2::GLES2Decoder* decoder,
+    GLuint dest_texture,
+    GLenum dest_texture_target,
+    GLenum dest_target,
+    GLenum luma_format,
+    GLenum luma_type,
+    GLint level,
+    GLint xoffset,
+    GLint yoffset,
+    GLint x,
+    GLint y,
+    GLsizei width,
+    GLsizei height,
+    GLuint source_framebuffer,
+    GLenum source_framebuffer_internal_format) {
+  DCHECK(initialized_);
+
+  // Copy the framebuffer to the first scratch texture
+  // TODO(geofflang): This could be optimized further by detecting if the source
+  // framebuffer is copying from a texture and sample directly from that texture
+  // instead of doing an extra copy
+
+  glBindFramebufferEXT(GL_FRAMEBUFFER, source_framebuffer);
+  glActiveTexture(GL_TEXTURE0);
+  glBindTexture(GL_TEXTURE_2D, scratch_textures_[0]);
+  glCopyTexImage2D(GL_TEXTURE_2D, 0, source_framebuffer_internal_format, x, y,
+                   width, height, 0);
+
+  // Set the swizzle of the scratch texture so that the channels sample into the
+  // correct emulated LUMA channels.
+  GLint swizzle[4] = {
+      (luma_format == GL_ALPHA) ? GL_ALPHA : GL_RED,
+      (luma_format == GL_LUMINANCE_ALPHA) ? GL_ALPHA : GL_ZERO, GL_ZERO,
+      GL_ZERO,
+  };
+  glTexParameteriv(GL_TEXTURE_2D, GL_TEXTURE_SWIZZLE_RGBA, swizzle);
+
+  // Make a temporary framebuffer using the second scratch texture to render the
+  // swizzled result to.
+  // TODO(geofflang): Could be optimized more by rendering directly to the
+  // destination texture but this isn't always possible because the destination
+  // may be an incomplete cube map
+  GLenum compatability_format =
+      gles2::TextureManager::AdjustTexFormat(feature_info_.get(), luma_format);
+  glBindTexture(GL_TEXTURE_2D, scratch_textures_[1]);
+  glTexImage2D(GL_TEXTURE_2D, 0, compatability_format, width, height, 0,

[Zhenyao Mo, 2016/06/01 18:24:18]

You will need to glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0) first, in case a buffer
is bound and not big enough, resulting an GL error and fails all the following
operation.

[Geoff Lang, 2016/06/01 20:12:18]

Ah, good point, fixed.

+               compatability_format, luma_type, nullptr);
+
+  glBindFramebufferEXT(GL_FRAMEBUFFER, scratch_fbo_);
+  glFramebufferTexture2DEXT(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D,
+                            scratch_textures_[1], 0);
+
+  // Render to the destination texture, sampling from the scratch texture
+  glUseProgram(blit_program_);
+  glViewport(0, 0, width, height);
+  glDisable(GL_SCISSOR_TEST);
+  glDisable(GL_DEPTH_TEST);
+  glDisable(GL_STENCIL_TEST);
+  glDisable(GL_CULL_FACE);

[Zhenyao Mo, 2016/06/01 18:24:18]

Should we also disable GL_DITHER?

[Geoff Lang, 2016/06/01 20:12:18]

Done.

+  glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
+  glDepthMask(GL_FALSE);
+  glDisable(GL_BLEND);
+  glBindTexture(GL_TEXTURE_2D, scratch_textures_[0]);
+  glBindVertexArrayOES(vao_);
+
+  glDrawArrays(GL_TRIANGLES, 0, 6);
+
+  // Finally, copy the swizzled texture to the destination texture
+  glBindTexture(dest_texture_target, dest_texture);
+  glCopyTexSubImage2D(dest_target, level, xoffset, yoffset, 0, 0, width,
+                      height);
+
+  // Restore state
+  decoder->RestoreAllAttributes();
+  decoder->RestoreTextureUnitBindings(0);
+  decoder->RestoreActiveTexture();
+  decoder->RestoreProgramBindings();
+  decoder->RestoreBufferBindings();
+  decoder->RestoreFramebufferBindings();
+  decoder->RestoreGlobalState();
+}
+
+// static
+bool CopyTexImageResourceManager::CopyTexImageRequiresBlit(
+    const gles2::FeatureInfo* feature_info,
+    GLenum dest_texture_format) {
+  if (feature_info->gl_version_info().is_desktop_core_profile) {
+    switch (dest_texture_format) {
+      case GL_LUMINANCE:
+      case GL_ALPHA:
+      case GL_LUMINANCE_ALPHA:
+        return true;
+    }
+  }
+
+  return false;
+}
+
+}  // namespace gpu