ObjC: Split out I420 texture uploading into separate class

webrtc/sdk/objc/Framework/Classes/RTCI420TextureCache.mm

Index: webrtc/sdk/objc/Framework/Classes/RTCI420TextureCache.mm
diff --git a/webrtc/sdk/objc/Framework/Classes/RTCI420Shader.mm b/webrtc/sdk/objc/Framework/Classes/RTCI420TextureCache.mm
similarity index 50%
copy from webrtc/sdk/objc/Framework/Classes/RTCI420Shader.mm
copy to webrtc/sdk/objc/Framework/Classes/RTCI420TextureCache.mm
index 3c3ffa72f003c5a9267584bed12cb85f718b34b8..d263c75e939713e0ffbd41d1924fbf6087a18976 100644
--- a/webrtc/sdk/objc/Framework/Classes/RTCI420Shader.mm
+++ b/webrtc/sdk/objc/Framework/Classes/RTCI420TextureCache.mm
@@ -1,5 +1,5 @@
 /*
- *  Copyright 2016 The WebRTC project authors. All Rights Reserved.
+ *  Copyright 2017 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
@@ -8,66 +8,40 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#import "RTCShader.h"
-
-#include <vector>
+#import "RTCI420TextureCache.h"
 
 #import "RTCShader+Private.h"
-#import "WebRTC/RTCLogging.h"
-#import "WebRTC/RTCVideoFrame.h"
 
-#include "webrtc/base/optional.h"
+#include <vector>
 
-// |kNumTextures| must not exceed 8, which is the limit in OpenGLES2. Two sets
-// of 3 textures are used here, one for each of the Y, U and V planes. Having
-// two sets alleviates CPU blockage in the event that the GPU is asked to render
-// to a texture that is already in use.
+// Two sets of 3 textures are used here, one for each of the Y, U and V planes. Having two sets
+// alleviates CPU blockage in the event that the GPU is asked to render to a texture that is already
+// in use.
 static const GLsizei kNumTextureSets = 2;
 static const GLsizei kNumTexturesPerSet = 3;
 static const GLsizei kNumTextures = kNumTexturesPerSet * kNumTextureSets;
 
-// Fragment shader converts YUV values from input textures into a final RGB
-// pixel. The conversion formula is from http://www.fourcc.org/fccyvrgb.php.
-static const char kI420FragmentShaderSource[] =
-  SHADER_VERSION
-  "precision highp float;"
-  FRAGMENT_SHADER_IN " vec2 v_texcoord;\n"
-  "uniform lowp sampler2D s_textureY;\n"
-  "uniform lowp sampler2D s_textureU;\n"
-  "uniform lowp sampler2D s_textureV;\n"
-  FRAGMENT_SHADER_OUT
-  "void main() {\n"
-  "    float y, u, v, r, g, b;\n"
-  "    y = " FRAGMENT_SHADER_TEXTURE "(s_textureY, v_texcoord).r;\n"
-  "    u = " FRAGMENT_SHADER_TEXTURE "(s_textureU, v_texcoord).r;\n"
-  "    v = " FRAGMENT_SHADER_TEXTURE "(s_textureV, v_texcoord).r;\n"
-  "    u = u - 0.5;\n"
-  "    v = v - 0.5;\n"
-  "    r = y + 1.403 * v;\n"
-  "    g = y - 0.344 * u - 0.714 * v;\n"
-  "    b = y + 1.770 * u;\n"
-  "    " FRAGMENT_SHADER_COLOR " = vec4(r, g, b, 1.0);\n"
-  "  }\n";
-
-@implementation RTCI420Shader {
+@implementation RTCI420TextureCache {
   BOOL _hasUnpackRowLength;
   GLint _currentTextureSet;
   // Handles for OpenGL constructs.
   GLuint _textures[kNumTextures];
-  GLuint _i420Program;
-  GLuint _vertexArray;
-  GLuint _vertexBuffer;
-  GLint _ySampler;
-  GLint _uSampler;
-  GLint _vSampler;
-  // Store current rotation and only upload new vertex data when rotation
-  // changes.
-  rtc::Optional<RTCVideoRotation> _currentRotation;
-  // Used to create a non-padded plane for GPU upload when we receive padded
-  // frames.
+  // Used to create a non-padded plane for GPU upload when we receive padded frames.
   std::vector<uint8_t> _planeBuffer;
 }
 
+- (GLuint)yTexture {
+  return _textures[_currentTextureSet * kNumTexturesPerSet];
+}
+
+- (GLuint)uTexture {
+  return _textures[_currentTextureSet * kNumTexturesPerSet + 1];
+}
+
+- (GLuint)vTexture {
+  return _textures[_currentTextureSet * kNumTexturesPerSet + 2];
+}
+
 - (instancetype)initWithContext:(GlContextType *)context {
   if (self = [super init]) {
 #if TARGET_OS_IPHONE
@@ -76,35 +50,17 @@ static const char kI420FragmentShaderSource[] =
     _hasUnpackRowLength = YES;
 #endif
     glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
-    if (![self setupI420Program] || ![self setupTextures] ||
-        !RTCSetupVerticesForProgram(_i420Program, &_vertexBuffer, &_vertexArray)) {
-      RTCLog(@"Failed to initialize RTCI420Shader.");
-      self = nil;
-    }
+
+    [self setupTextures];
   }
   return self;
 }
 
 - (void)dealloc {
-  glDeleteProgram(_i420Program);
   glDeleteTextures(kNumTextures, _textures);
-  glDeleteBuffers(1, &_vertexBuffer);
-  glDeleteVertexArrays(1, &_vertexArray);
-}
-
-- (BOOL)setupI420Program {
-  _i420Program = RTCCreateProgramFromFragmentSource(kI420FragmentShaderSource);
-  if (!_i420Program) {
-    return NO;
-  }
-  _ySampler = glGetUniformLocation(_i420Program, "s_textureY");
-  _uSampler = glGetUniformLocation(_i420Program, "s_textureU");
-  _vSampler = glGetUniformLocation(_i420Program, "s_textureV");
-
-  return (_ySampler >= 0 && _uSampler >= 0 && _vSampler >= 0);
 }
 
-- (BOOL)setupTextures {
+- (void)setupTextures {
   glGenTextures(kNumTextures, _textures);
   // Set parameters for each of the textures we created.
   for (GLsizei i = 0; i < kNumTextures; i++) {
@@ -114,39 +70,15 @@ static const char kI420FragmentShaderSource[] =
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
   }
-  return YES;
-}
-
-- (BOOL)drawFrame:(RTCVideoFrame*)frame {
-  glUseProgram(_i420Program);
-  if (![self updateTextureDataForFrame:frame]) {
-    return NO;
-  }
-#if !TARGET_OS_IPHONE
-  glBindVertexArray(_vertexArray);
-#endif
-  glBindBuffer(GL_ARRAY_BUFFER, _vertexBuffer);
-  if (!_currentRotation || frame.rotation != *_currentRotation) {
-    _currentRotation = rtc::Optional<RTCVideoRotation>(frame.rotation);
-    RTCSetVertexData(*_currentRotation);
-  }
-  glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
-
-  return YES;
 }
 
 - (void)uploadPlane:(const uint8_t *)plane
-            sampler:(GLint)sampler
-             offset:(GLint)offset
+            texture:(GLuint)texture
               width:(size_t)width
              height:(size_t)height
              stride:(int32_t)stride {
-  glActiveTexture(static_cast<GLenum>(GL_TEXTURE0 + offset));
-  glBindTexture(GL_TEXTURE_2D, _textures[offset]);
+  glBindTexture(GL_TEXTURE_2D, texture);
 
-  // When setting texture sampler uniforms, the texture index is used not
-  // the texture handle.
-  glUniform1i(sampler, offset);
   const uint8_t *uploadPlane = plane;
   if ((size_t)stride != width) {
    if (_hasUnpackRowLength) {
@@ -184,9 +116,8 @@ static const char kI420FragmentShaderSource[] =
                uploadPlane);
 }
 
-- (BOOL)updateTextureDataForFrame:(RTCVideoFrame *)frame {
-  GLint textureOffset = _currentTextureSet * 3;
-  NSAssert(textureOffset + 3 <= kNumTextures, @"invalid offset");
+- (void)uploadFrameToTextures:(RTCVideoFrame *)frame {
+  _currentTextureSet = (_currentTextureSet + 1) % kNumTextureSets;
 
   const int chromaWidth = (frame.width + 1) / 2;
   const int chromaHeight = (frame.height + 1) / 2;
@@ -197,28 +128,22 @@ static const char kI420FragmentShaderSource[] =
   }
 
   [self uploadPlane:frame.dataY
-            sampler:_ySampler
-             offset:textureOffset
+            texture:self.yTexture
               width:frame.width
              height:frame.height
              stride:frame.strideY];
 
   [self uploadPlane:frame.dataU
-            sampler:_uSampler
-             offset:textureOffset + 1
+            texture:self.uTexture
               width:chromaWidth
              height:chromaHeight
              stride:frame.strideU];
 
   [self uploadPlane:frame.dataV
-            sampler:_vSampler
-             offset:textureOffset + 2
+            texture:self.vTexture
               width:chromaWidth
              height:chromaHeight
              stride:frame.strideV];
-
-  _currentTextureSet = (_currentTextureSet + 1) % kNumTextureSets;
-  return YES;
 }
 
 @end