Addition of GL_CHROMIUM_copy_texture extension.

gpu/command_buffer/service/gles2_cmd_copy_texture_chromium.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 "gpu/command_buffer/service/gles2_cmd_copy_texture_chromium.h"
+
+#include "base/basictypes.h"
+#include "gpu/command_buffer/common/types.h"
+#include "gpu/command_buffer/service/gl_utils.h"
+
+#define SHADER0(Src) \
+    "#ifdef GL_ES\n"\
+    "precision mediump float;\n"\
+    "#endif\n"\
+    #Src
+#define SHADER(Src) SHADER0(Src)
+
+namespace {
+
+const GLfloat kQuadVertices[] = { -1.0f, -1.0f, 0.0f, 1.0f,
+                                   1.0f, -1.0f, 0.0f, 1.0f,
+                                   1.0f,  1.0f, 0.0f, 1.0f,
+                                  -1.0f,  1.0f, 0.0f, 1.0f };
+
+const GLfloat kTextureCoords[] = { 0.0f, 0.0f,
+                                   1.0f, 0.0f,
+                                   1.0f, 1.0f,
+                                   0.0f, 1.0f };
+
+const int kNumShaders = 5;
+enum ShaderId {
+  VERTEX_SHADER_POS_TEX,
+  FRAGMENT_SHADER_TEX,
+  FRAGMENT_SHADER_TEX_FLIP_Y,
+  FRAGMENT_SHADER_TEX_PREMULTIPLY_ALPHA,
+  FRAGMENT_SHADER_TEX_PREMULTIPLY_ALPHA_FLIP_Y
+};
+
+enum ProgramId {
+  PROGRAM_COPY_TEXTURE,
+  PROGRAM_COPY_TEXTURE_FLIP_Y,
+  PROGRAM_COPY_TEXTURE_PREMULTIPLY_ALPHA,
+  PROGRAM_COPY_TEXTURE_PREMULTIPLY_ALPHA_FLIPY
+};
+
+// Returns the correct program to evaluate the copy operation for
+// the CHROMIUM_flipy and premultiply alpha pixel store settings.
+ProgramId GetProgram(bool flip_y, bool premultiply_alpha) {
+  if (flip_y && premultiply_alpha)
+    return PROGRAM_COPY_TEXTURE_PREMULTIPLY_ALPHA_FLIPY;
+
+  if (flip_y)
+    return PROGRAM_COPY_TEXTURE_FLIP_Y;
+
+  if (premultiply_alpha)
+    return PROGRAM_COPY_TEXTURE_PREMULTIPLY_ALPHA;
+
+  return PROGRAM_COPY_TEXTURE;
+}
+
+const char* GetShaderSource(ShaderId shader) {
+  switch (shader) {
+    case VERTEX_SHADER_POS_TEX:
+      return SHADER(
+        attribute vec4 a_position;
+        attribute vec2 a_texCoord;
+        varying vec2 v_uv;
+        void main(void) {
+          gl_Position = a_position;
+          v_uv = a_texCoord;
+        });
+    case FRAGMENT_SHADER_TEX:
+      return SHADER(
+        uniform sampler2D u_texSampler;
+        varying vec2 v_uv;
+        void main(void) {
+          gl_FragColor = texture2D(u_texSampler, v_uv.st);
+        });
+    case FRAGMENT_SHADER_TEX_FLIP_Y:
+      return SHADER(
+        uniform sampler2D u_texSampler;
+        varying vec2 v_uv;
+        void main(void) {
+          gl_FragColor = texture2D(u_texSampler, vec2(v_uv.s, 1.0 - v_uv.t));
+        });
+    case FRAGMENT_SHADER_TEX_PREMULTIPLY_ALPHA:
+      return SHADER(
+        uniform sampler2D u_texSampler;
+        varying vec2 v_uv;
+        void main(void) {
+          gl_FragColor = texture2D(u_texSampler, v_uv.st);
+          gl_FragColor.rgb *= gl_FragColor.a;
+        });
+    case FRAGMENT_SHADER_TEX_PREMULTIPLY_ALPHA_FLIP_Y:
+      return SHADER(
+        uniform sampler2D u_texSampler;
+        varying vec2 v_uv;
+        void main(void) {
+          gl_FragColor = texture2D(u_texSampler, vec2(v_uv.s, 1.0 - v_uv.t));
+          gl_FragColor.rgb *= gl_FragColor.a;
+        });
+    default:
+      return 0;
+  }
+}
+
+}  // namespace
+
+void CopyTextureCHROMIUMResourceManager::Initialize() {
+  COMPILE_ASSERT(
+      kVertexPositionAttrib == 0u || kVertexTextureAttrib == 0u,
+      CopyTexture_One_of_these_attribs_must_be_0);
+
+  // Initialize all of the GPU resources required to perform the copy.
+  glGenBuffersARB(2, buffer_ids_);
+  glBindBuffer(GL_ARRAY_BUFFER, buffer_ids_[0]);
+  glBufferData(GL_ARRAY_BUFFER, sizeof(kQuadVertices), kQuadVertices,
+               GL_STATIC_DRAW);
+
+  glBindBuffer(GL_ARRAY_BUFFER, buffer_ids_[1]);
+  glBufferData(GL_ARRAY_BUFFER, sizeof(kTextureCoords), kTextureCoords,
+               GL_STATIC_DRAW);
+
+  glGenFramebuffersEXT(1, &framebuffer_);
+
+  GLuint shaders[kNumShaders];
+  for (int shader = 0; shader < kNumShaders; ++shader) {
+    shaders[shader] = glCreateShader(
+        shader == 0 ? GL_VERTEX_SHADER : GL_FRAGMENT_SHADER);
+    const char* shader_source = GetShaderSource(static_cast<ShaderId>(shader));
+    glShaderSource(shaders[shader], 1, &shader_source, 0);
+    glCompileShader(shaders[shader]);
+#ifndef NDEBUG
+    GLint compile_status;
+    glGetShaderiv(shaders[shader], GL_COMPILE_STATUS, &compile_status);
+    if (GL_TRUE != compile_status)
+      DLOG(ERROR) << "CopyTextureCHROMIUM: shader compilation failure.";
+#endif
+  }
+
+  for (int program = 0; program < kNumPrograms; ++program) {
+    programs_[program] = glCreateProgram();
+    glAttachShader(programs_[program], shaders[0]);
+    glAttachShader(programs_[program], shaders[program + 1]);
+
+    glBindAttribLocation(programs_[program], kVertexPositionAttrib,
+                         "a_position");
+    glBindAttribLocation(programs_[program], kVertexTextureAttrib,
+                         "a_texCoord");
+
+    glLinkProgram(programs_[program]);
+#ifndef NDEBUG
+    GLint linked;
+    glGetProgramiv(programs_[program], GL_LINK_STATUS, &linked);
+    if (!linked)
+      DLOG(ERROR) << "CopyTextureCHROMIUM: program link failure.";
+#endif
+
+    sampler_locations_[program] = glGetUniformLocation(programs_[program],
+                                                      "u_texSampler");
+  }
+
+  for (int shader = 0; shader < kNumShaders; ++shader)
+    glDeleteShader(shaders[shader]);
+
+  initialized_ = true;
+}
+
+void CopyTextureCHROMIUMResourceManager::Destroy() {
+  if (!initialized_)
+    return;
+
+  glDeleteFramebuffersEXT(1, &framebuffer_);
+
+  for (int program = 0; program < kNumPrograms; ++program)
+    glDeleteProgram(programs_[program]);
+
+  glDeleteBuffersARB(2, buffer_ids_);
+}
+
+void CopyTextureCHROMIUMResourceManager::DoCopyTexture(
+    GLenum target,
+    GLuint source_id,
+    GLuint dest_id,
+    GLint level,
+    bool flip_y,
+    bool premultiply_alpha) {
+  if (!initialized_) {
+    DLOG(ERROR) << "CopyTextureCHROMIUM: Uninitialized manager.";
+    return;
+  }
+
+  GLuint program = GetProgram(flip_y, premultiply_alpha);
+  glUseProgram(programs_[program]);
+
+#ifndef NDEBUG
+  glValidateProgram(programs_[program]);
+  GLint validation_status;
+  glGetProgramiv(programs_[program], GL_VALIDATE_STATUS, &validation_status);
+  if (GL_TRUE != validation_status) {
+    DLOG(ERROR) << "CopyTextureCHROMIUM: Invalid shader.";
+    return;
+  }
+#endif
+
+  glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, framebuffer_);
+  glFramebufferTexture2DEXT(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, target,
+                            dest_id, level);
+
+#ifndef NDEBUG
+  GLenum fb_status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER);
+  if (GL_FRAMEBUFFER_COMPLETE != fb_status) {
+    DLOG(ERROR) << "CopyTextureCHROMIUM: Incomplete framebuffer.";
+    return;
+  }
+#endif
+
+  glEnableVertexAttribArray(kVertexPositionAttrib);
+  glEnableVertexAttribArray(kVertexTextureAttrib);
+
+  glBindBuffer(GL_ARRAY_BUFFER, buffer_ids_[0]);
+  glVertexAttribPointer(kVertexPositionAttrib, 4, GL_FLOAT, GL_FALSE,
+                        4 * sizeof(GLfloat), 0);
+
+  glBindBuffer(GL_ARRAY_BUFFER, buffer_ids_[1]);
+  glVertexAttribPointer(kVertexTextureAttrib,  2, GL_FLOAT, GL_FALSE,
+                        2 * sizeof(GLfloat), 0);
+
+  glActiveTexture(GL_TEXTURE0);
+  glUniform1i(sampler_locations_[program], 0);
+
+  glBindTexture(GL_TEXTURE_2D, source_id);
+  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+
+  glDisable(GL_DEPTH_TEST);
+  glDisable(GL_SCISSOR_TEST);
+  glDisable(GL_STENCIL_TEST);
+  glDisable(GL_CULL_FACE);
+  glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
+  glDepthMask(GL_FALSE);
+  glDisable(GL_BLEND);
+
+  glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
+}
+