iOS: Add interface for injecting custom shaders

webrtc/sdk/objc/Framework/Classes/Video/RTCDefaultShader.mm

Index: webrtc/sdk/objc/Framework/Classes/Video/RTCDefaultShader.mm
diff --git a/webrtc/sdk/objc/Framework/Classes/Video/RTCDefaultShader.mm b/webrtc/sdk/objc/Framework/Classes/Video/RTCDefaultShader.mm
new file mode 100644
index 0000000000000000000000000000000000000000..95a1eda5cd592eb9e5029acd2bdebd3ed3ee6af3
--- /dev/null
+++ b/webrtc/sdk/objc/Framework/Classes/Video/RTCDefaultShader.mm
@@ -0,0 +1,203 @@
+/*
+ *  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
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#import "RTCDefaultShader.h"
+
+#if TARGET_OS_IPHONE
+#import <OpenGLES/ES3/gl.h>
+#else
+#import <OpenGL/gl3.h>
+#endif
+
+#import "RTCOpenGLDefines.h"
+#import "RTCShader.h"
+#import "WebRTC/RTCLogging.h"
+
+#include "webrtc/base/optional.h"
+
+static const int kYTextureUnit = 0;
+static const int kUTextureUnit = 1;
+static const int kVTextureUnit = 2;
+static const int kUvTextureUnit = 1;
+
+// 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";
+
+static const char kNV12FragmentShaderSource[] =
+  SHADER_VERSION
+  "precision mediump float;"
+  FRAGMENT_SHADER_IN " vec2 v_texcoord;\n"
+  "uniform lowp sampler2D s_textureY;\n"
+  "uniform lowp sampler2D s_textureUV;\n"
+  FRAGMENT_SHADER_OUT
+  "void main() {\n"
+  "    mediump float y;\n"
+  "    mediump vec2 uv;\n"
+  "    y = " FRAGMENT_SHADER_TEXTURE "(s_textureY, v_texcoord).r;\n"
+  "    uv = " FRAGMENT_SHADER_TEXTURE "(s_textureUV, v_texcoord).ra -\n"
+  "        vec2(0.5, 0.5);\n"
+  "    " FRAGMENT_SHADER_COLOR " = vec4(y + 1.403 * uv.y,\n"
+  "                                     y - 0.344 * uv.x - 0.714 * uv.y,\n"
+  "                                     y + 1.770 * uv.x,\n"
+  "                                     1.0);\n"
+  "  }\n";
+
+@implementation RTCDefaultShader {
+  GLuint _vertexBuffer;
+  GLuint _vertexArray;
+  // Store current rotation and only upload new vertex data when rotation changes.
+  rtc::Optional<RTCVideoRotation> _currentRotation;
+
+  GLuint _i420Program;
+  GLuint _nv12Program;
+}
+
+- (void)dealloc {
+  glDeleteProgram(_i420Program);
+  glDeleteProgram(_nv12Program);
+  glDeleteBuffers(1, &_vertexBuffer);
+  glDeleteVertexArrays(1, &_vertexArray);
+}
+
+- (BOOL)createAndSetupI420Program {
+  NSAssert(!_i420Program, @"I420 program already created");
+  _i420Program = RTCCreateProgramFromFragmentSource(kI420FragmentShaderSource);
+  if (!_i420Program) {
+    return NO;
+  }
+  GLint ySampler = glGetUniformLocation(_i420Program, "s_textureY");
+  GLint uSampler = glGetUniformLocation(_i420Program, "s_textureU");
+  GLint vSampler = glGetUniformLocation(_i420Program, "s_textureV");
+
+  if (ySampler < 0 || uSampler < 0 || vSampler < 0) {
+    RTCLog(@"Failed to get uniform variable locations in I420 shader");
+    glDeleteProgram(_i420Program);
+    _i420Program = 0;
+    return NO;
+  }
+
+  glUseProgram(_i420Program);
+  glUniform1i(ySampler, kYTextureUnit);
+  glUniform1i(uSampler, kUTextureUnit);
+  glUniform1i(vSampler, kVTextureUnit);
+
+  return YES;
+}
+
+- (BOOL)createAndSetupNV12Program {
+  NSAssert(!_nv12Program, @"NV12 program already created");
+  _nv12Program = RTCCreateProgramFromFragmentSource(kNV12FragmentShaderSource);
+  if (!_nv12Program) {
+    return NO;
+  }
+  GLint ySampler = glGetUniformLocation(_nv12Program, "s_textureY");
+  GLint uvSampler = glGetUniformLocation(_nv12Program, "s_textureUV");
+
+  if (ySampler < 0 || uvSampler < 0) {
+    RTCLog(@"Failed to get uniform variable locations in NV12 shader");
+    glDeleteProgram(_nv12Program);
+    _nv12Program = 0;
+    return NO;
+  }
+
+  glUseProgram(_nv12Program);
+  glUniform1i(ySampler, kYTextureUnit);
+  glUniform1i(uvSampler, kUvTextureUnit);
+
+  return YES;
+}
+
+- (BOOL)prepareVertexBufferWithRotation:(RTCVideoRotation)rotation {
+  if (!_vertexBuffer && !RTCCreateVertexBuffer(&_vertexBuffer, &_vertexArray)) {
+    RTCLog(@"Failed to setup vertex buffer");
+    return NO;
+  }
+#if !TARGET_OS_IPHONE
+  glBindVertexArray(_vertexArray);
+#endif
+  glBindBuffer(GL_ARRAY_BUFFER, _vertexBuffer);
+  if (!_currentRotation || rotation != *_currentRotation) {
+    _currentRotation = rtc::Optional<RTCVideoRotation>(rotation);
+    RTCSetVertexData(*_currentRotation);
+  }
+  return YES;
+}
+
+- (void)applyShadingForFrameWithRotation:(RTCVideoRotation)rotation
+                                  yPlane:(GLuint)yPlane
+                                  uPlane:(GLuint)uPlane
+                                  vPlane:(GLuint)vPlane {
+  if (![self prepareVertexBufferWithRotation:rotation]) {
+    return;
+  }
+
+  if (!_i420Program && ![self createAndSetupI420Program]) {
+    RTCLog(@"Failed to setup I420 program");
+    return;
+  }
+
+  glUseProgram(_i420Program);
+
+  glActiveTexture(static_cast<GLenum>(GL_TEXTURE0 + kYTextureUnit));
+  glBindTexture(GL_TEXTURE_2D, yPlane);
+
+  glActiveTexture(static_cast<GLenum>(GL_TEXTURE0 + kUTextureUnit));
+  glBindTexture(GL_TEXTURE_2D, uPlane);
+
+  glActiveTexture(static_cast<GLenum>(GL_TEXTURE0 + kVTextureUnit));
+  glBindTexture(GL_TEXTURE_2D, vPlane);
+
+  glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
+}
+
+- (void)applyShadingForFrameWithRotation:(RTCVideoRotation)rotation
+                                  yPlane:(GLuint)yPlane
+                                 uvPlane:(GLuint)uvPlane {
+  if (![self prepareVertexBufferWithRotation:rotation]) {
+    return;
+  }
+
+  if (!_nv12Program && ![self createAndSetupNV12Program]) {
+    RTCLog(@"Failed to setup NV12 shader");
+    return;
+  }
+
+  glUseProgram(_nv12Program);
+
+  glActiveTexture(static_cast<GLenum>(GL_TEXTURE0 + kYTextureUnit));
+  glBindTexture(GL_TEXTURE_2D, yPlane);
+
+  glActiveTexture(static_cast<GLenum>(GL_TEXTURE0 + kUvTextureUnit));
+  glBindTexture(GL_TEXTURE_2D, uvPlane);
+
+  glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
+}
+
+@end