iOS: Add interface for injecting custom shaders

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

 /*
  *  Copyright 2016 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 "RTCShader.h"
 
+#if TARGET_OS_IPHONE
+#import <OpenGLES/ES3/gl.h>
+#else
+#import <OpenGL/gl3.h>
+#endif
+
 #include <algorithm>
 #include <array>
 #include <memory>
 
-#import "RTCShader+Private.h"
+#import "RTCOpenGLDefines.h"
 
 #include "webrtc/base/checks.h"
 #include "webrtc/base/logging.h"
 
 // Vertex shader doesn't do anything except pass coordinates through.
 const char kRTCVertexShaderSource[] =
   SHADER_VERSION
   VERTEX_SHADER_IN " vec2 position;\n"
   VERTEX_SHADER_IN " vec2 texcoord;\n"
   VERTEX_SHADER_OUT " vec2 v_texcoord;\n"
@@ skipping 60 matching lines @@
       RTCCreateShader(GL_FRAGMENT_SHADER, fragmentShaderSource);
   RTC_CHECK(fragmentShader) << "failed to create fragment shader";
   GLuint program = RTCCreateProgram(vertexShader, fragmentShader);
   // Shaders are created only to generate program.
   if (vertexShader) {
     glDeleteShader(vertexShader);
   }
   if (fragmentShader) {
     glDeleteShader(fragmentShader);
   }
+
+  // Set vertex shader variables 'position' and 'texcoord' in program.
+  GLint position = glGetAttribLocation(program, "position");
+  GLint texcoord = glGetAttribLocation(program, "texcoord");
+  if (position < 0 || texcoord < 0) {
+    glDeleteProgram(program);
+    return 0;
+  }
+
+  // Read position attribute with size of 2 and stride of 4 beginning at the start of the array. The
+  // last argument indicates offset of data within the vertex buffer.
+  glVertexAttribPointer(position, 2, GL_FLOAT, GL_FALSE, 4 * sizeof(GLfloat), (void *)0);
+  glEnableVertexAttribArray(position);
+
+  // Read texcoord attribute  with size of 2 and stride of 4 beginning at the first texcoord in the
+  // array. The last argument indicates offset of data within the vertex buffer.
+  glVertexAttribPointer(texcoord, 2, GL_FLOAT, GL_FALSE, 4 * sizeof(GLfloat),
+                        (void *)(2 * sizeof(GLfloat)));
+  glEnableVertexAttribArray(texcoord);
+
   return program;
 }
 
-// Set vertex shader variables 'position' and 'texcoord' in |program| to use
-// |vertexBuffer| and |vertexArray| to store the vertex data.
-BOOL RTCSetupVerticesForProgram(GLuint program, GLuint* vertexBuffer, GLuint* vertexArray) {
-  GLint position = glGetAttribLocation(program, "position");
-  GLint texcoord = glGetAttribLocation(program, "texcoord");
-  if (position < 0 || texcoord < 0) {
-    return NO;
-  }
+BOOL RTCCreateVertexBuffer(GLuint *vertexBuffer, GLuint *vertexArray) {
 #if !TARGET_OS_IPHONE
   glGenVertexArrays(1, vertexArray);
   if (*vertexArray == 0) {
     return NO;
   }
   glBindVertexArray(*vertexArray);
 #endif
   glGenBuffers(1, vertexBuffer);
   if (*vertexBuffer == 0) {
     return NO;

[sakal, 2017/05/11 10:45:47]

Delete vertex array if we created one?

[magjed_webrtc, 2017/05/11 12:38:06]

Done.

   }
   glBindBuffer(GL_ARRAY_BUFFER, *vertexBuffer);
   glBufferData(GL_ARRAY_BUFFER, 4 * 4 * sizeof(GLfloat), NULL, GL_DYNAMIC_DRAW);
-
-  // Read position attribute with size of 2 and stride of 4 beginning at the
-  // start of the array. The last argument indicates offset of data within the
-  // vertex buffer.
-  glVertexAttribPointer(position, 2, GL_FLOAT, GL_FALSE, 4 * sizeof(GLfloat),
-                        (void *)0);
-  glEnableVertexAttribArray(position);
-
-  // Read texcoord attribute from |gVertices| with size of 2 and stride of 4
-  // beginning at the first texcoord in the array. The last argument indicates
-  // offset of data within |gVertices| as supplied to the vertex buffer.
-  glVertexAttribPointer(texcoord, 2, GL_FLOAT, GL_FALSE, 4 * sizeof(GLfloat),
-                        (void *)(2 * sizeof(GLfloat)));
-  glEnableVertexAttribArray(texcoord);
-
   return YES;
 }
 
 // Set vertex data to the currently bound vertex buffer.
 void RTCSetVertexData(RTCVideoRotation rotation) {
   // When modelview and projection matrices are identity (default) the world is
   // contained in the square around origin with unit size 2. Drawing to these
   // coordinates is equivalent to drawing to the entire screen. The texture is
   // stretched over that square using texture coordinates (u, v) that range
   // from (0, 0) to (1, 1) inclusive. Texture coordinates are flipped vertically
@@ skipping 28 matching lines @@
   const GLfloat gVertices[] = {
       // X, Y, U, V.
       -1, -1, UVCoords[0][0], UVCoords[0][1],
        1, -1, UVCoords[1][0], UVCoords[1][1],
        1,  1, UVCoords[2][0], UVCoords[2][1],
       -1,  1, UVCoords[3][0], UVCoords[3][1],
   };
 
   glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(gVertices), gVertices);
 }