Added Multiple Render Targets example

glBlitFramebuffer does not seem to work with PowerVR Emulator v3.2 but
works with Mali ARM Emulator v1.3.

CMakeLists.txt

@@ -25,6 +25,7 @@ SUBDIRS( Common
          Chapter_9/MipMap2D
          Chapter_9/TextureWrap
          Chapter_10/MultiTexture
+         Chapter_11/MRTs
          Chapter_14/Noise3D
          Chapter_14/ParticleSystem
          Chapter_14/ParticleSystemTransformFeedback 

Chapter_11/MRTs/CMakeLists.txt

@@ -0,0 +1,2 @@
+add_executable( MRTs MRTs.c )
+target_link_libraries( MRTs Common )

Chapter_11/MRTs/MRTs.c

@@ -0,0 +1,295 @@
+// The MIT License (MIT)
+//
+// Copyright (c) 2013 Dan Ginsburg, Budirijanto Purnomo
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+//
+// Book:      OpenGL(R) ES 3.0 Programming Guide, 2nd Edition
+// Authors:   Dan Ginsburg, Budirijanto Purnomo, Dave Shreiner, Aaftab Munshi
+// ISBN-10:   0-321-93388-5
+// ISBN-13:   978-0-321-93388-1
+// Publisher: Addison-Wesley Professional
+// URLs:      http://www.opengles-book.com
+//            http://my.safaribooksonline.com/book/animation-and-3d/9780133440133
+//
+// MRTs.c
+//
+//    This is an example to demonstrate Multiple Render Targets and framebuffer blits.
+//    The first rendering pass will output four colors (red, green, blue, gray)
+//    per fragment using MRTs.
+//    The second pass will copy the four color buffers into four screen quadrant
+//    using framebuffer blits.
+//
+#include <stdlib.h>
+#include "esUtil.h"
+
+typedef struct
+{
+   // Handle to a program object
+   GLuint programObject;
+
+   // Handle to a framebuffer object
+   GLuint fbo;
+
+   // Texture handle
+   GLuint colorTexId[4];
+
+   // Texture size
+   GLsizei textureWidth;
+   GLsizei textureHeight;
+
+} UserData;
+
+///
+// Initialize the framebuffer object and MRTs
+//
+int InitFBO ( ESContext *esContext )
+{
+   UserData *userData = esContext->userData;
+   int i;
+   GLint defaultFramebuffer = 0;
+   const GLenum attachments[4] = 
+   { 
+      GL_COLOR_ATTACHMENT0,
+      GL_COLOR_ATTACHMENT1,
+      GL_COLOR_ATTACHMENT2,
+      GL_COLOR_ATTACHMENT3 
+   };
+
+   glGetIntegerv ( GL_FRAMEBUFFER_BINDING, &defaultFramebuffer );
+
+   // Setup fbo
+   glGenFramebuffers ( 1, &userData->fbo );
+   glBindFramebuffer ( GL_FRAMEBUFFER, userData->fbo );
+
+   // Setup four output buffers and attach to fbo
+   userData->textureHeight = userData->textureWidth = 400;
+   glGenTextures ( 4, &userData->colorTexId[0] );
+   for (i = 0; i < 4; ++i)
+   {
+      glBindTexture ( GL_TEXTURE_2D, userData->colorTexId[i] );
+
+      glTexImage2D ( GL_TEXTURE_2D, 0, GL_RGBA, 
+                     userData->textureWidth, userData->textureHeight, 
+                     0, GL_RGBA, GL_UNSIGNED_BYTE, NULL );
+
+      // Set the filtering mode
+      glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST );
+      glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST );
+
+      glFramebufferTexture2D ( GL_DRAW_FRAMEBUFFER, attachments[i], 
+                               GL_TEXTURE_2D, userData->colorTexId[i], 0 );
+   }
+
+   glDrawBuffers ( 4, attachments );
+
+   if ( GL_FRAMEBUFFER_COMPLETE != glCheckFramebufferStatus ( GL_FRAMEBUFFER ) )
+   {
+      return FALSE;
+   }
+
+   // Restore the original framebuffer
+   glBindFramebuffer ( GL_FRAMEBUFFER, defaultFramebuffer );
+
+   return TRUE;
+}
+
+///
+// Initialize the shader and program object
+//
+int Init ( ESContext *esContext )
+{
+   UserData *userData = esContext->userData;
+   char vShaderStr[] =
+      "#version 300 es                            \n"
+      "layout(location = 0) in vec4 a_position;   \n"
+      "void main()                                \n"
+      "{                                          \n"
+      "   gl_Position = a_position;               \n"
+      "}                                          \n";
+
+   char fShaderStr[] =
+       "#version 300 es                                     \n"
+       "precision mediump float;                            \n"
+       "layout(location = 0) out vec4 fragData0;            \n"
+       "layout(location = 1) out vec4 fragData1;            \n"
+       "layout(location = 2) out vec4 fragData2;            \n"
+       "layout(location = 3) out vec4 fragData3;            \n"
+       "void main()                                         \n"
+       "{                                                   \n"
+       "  // first buffer will contain red color            \n"
+       "  fragData0 = vec4 ( 1, 0, 0, 1 );                  \n"
+       "                                                    \n"
+       "  // second buffer will contain green color         \n"
+       "  fragData1 = vec4 ( 0, 1, 0, 1 );                  \n"
+       "                                                    \n"
+       "  // third buffer will contain blue color           \n"
+       "  fragData2 = vec4 ( 0, 0, 1, 1 );                  \n"
+       "                                                    \n"
+       "  // fourth buffer will contain gray color          \n"            
+       "  fragData3 = vec4 ( 0.5, 0.5, 0.5, 1 );            \n"
+       "}                                                   \n";
+
+   // Load the shaders and get a linked program object
+   userData->programObject = esLoadProgram ( vShaderStr, fShaderStr );
+
+   InitFBO ( esContext );
+
+   glClearColor ( 1.0f, 1.0f, 1.0f, 0.0f );
+   return TRUE;
+}
+
+///
+// Draw a quad and output four colors per pixel
+//
+void DrawGeometry ( ESContext *esContext )
+{
+   UserData *userData = esContext->userData;
+   GLfloat vVertices[] = { -0.5f,  0.5f, 0.0f,  
+                           -0.5f, -0.5f, 0.0f,  
+                            0.5f, -0.5f, 0.0f,  
+                            0.5f,  0.5f, 0.0f, 
+                         };
+   GLushort indices[] = { 0, 1, 2, 0, 2, 3 };
+
+   // Set the viewport
+   glViewport ( 0, 0, esContext->width, esContext->height );
+
+   // Clear the color buffer
+   glClear ( GL_COLOR_BUFFER_BIT );
+
+   // Use the program object
+   glUseProgram ( userData->programObject );
+
+   // Load the vertex position
+   glVertexAttribPointer ( 0, 3, GL_FLOAT,
+                           GL_FALSE, 3 * sizeof ( GLfloat ), vVertices );
+   glEnableVertexAttribArray ( 0 );
+
+   // Draw a quad
+   glDrawElements ( GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, indices );
+}
+
+///
+// Copy MRT output buffers to screen
+//
+void BlitTextures ( ESContext *esContext )
+{
+   UserData *userData = esContext->userData;
+
+   // set the fbo for reading
+   glBindFramebuffer ( GL_READ_FRAMEBUFFER, userData->fbo );
+
+   // Copy the output red buffer to lower left quadrant
+   glReadBuffer ( GL_COLOR_ATTACHMENT0 );
+   glBlitFramebuffer ( 0, 0, esContext->width, esContext->height,
+                       0, 0, esContext->width/2, esContext->height/2, 
+                       GL_COLOR_BUFFER_BIT, GL_LINEAR );
+
+   // Copy the output green buffer to lower right quadrant
+   glReadBuffer ( GL_COLOR_ATTACHMENT1 );
+   glBlitFramebuffer ( 0, 0, esContext->width, esContext->height,
+                       esContext->width/2, 0, esContext->width, esContext->height/2, 
+                       GL_COLOR_BUFFER_BIT, GL_LINEAR );
+
+   // Copy the output blue buffer to upper left quadrant
+   glReadBuffer ( GL_COLOR_ATTACHMENT2 );
+   glBlitFramebuffer ( 0, 0, esContext->width, esContext->height,
+                       0, esContext->height/2, esContext->width/2, esContext->height, 
+                       GL_COLOR_BUFFER_BIT, GL_LINEAR );
+
+   // Copy the output gray buffer to upper right quadrant
+   glReadBuffer ( GL_COLOR_ATTACHMENT3 );
+   glBlitFramebuffer ( 0, 0, esContext->width, esContext->height,
+                       esContext->width/2, esContext->height/2, esContext->width, esContext->height, 
+                       GL_COLOR_BUFFER_BIT, GL_LINEAR );
+}
+
+///
+// Render to MRTs and screen
+//
+void Draw ( ESContext *esContext )
+{
+   UserData *userData = esContext->userData;
+   GLint defaultFramebuffer = 0;
+   const GLenum attachments[4] = 
+   { 
+      GL_COLOR_ATTACHMENT0,
+      GL_COLOR_ATTACHMENT1,
+      GL_COLOR_ATTACHMENT2,
+      GL_COLOR_ATTACHMENT3 
+   };
+   GLenum back[4] = 
+   {
+       GL_BACK,
+       GL_BACK,
+       GL_BACK,
+       GL_BACK 
+   };
+
+   glGetIntegerv ( GL_FRAMEBUFFER_BINDING, &defaultFramebuffer );
+
+   // FIRST PASS: use MRTs to output four colors to four buffers
+   glBindFramebuffer ( GL_FRAMEBUFFER, userData->fbo );
+   glDrawBuffers ( 4, attachments );
+   DrawGeometry ( esContext );
+
+   // SECOND PASS: draw the four output textures into four quadrant of windows
+   // with framebuffer blits
+   // Restore the default framebuffer
+   glBindFramebuffer ( GL_DRAW_FRAMEBUFFER, defaultFramebuffer );
+   glDrawBuffers ( 4, back );
+   glClear ( GL_COLOR_BUFFER_BIT );
+   BlitTextures ( esContext );
+}
+
+///
+// Cleanup
+//
+void ShutDown ( ESContext *esContext )
+{
+   UserData *userData = esContext->userData;
+
+   // Delete texture objects
+   glDeleteTextures ( 4, userData->colorTexId );
+
+   // Delete fbo
+   glDeleteFramebuffers ( 1, &userData->fbo );
+
+   // Delete program object
+   glDeleteProgram ( userData->programObject );
+}
+
+int esMain ( ESContext *esContext )
+{
+   esContext->userData = malloc ( sizeof ( UserData ) );
+
+   esCreateWindow ( esContext, "Multiple Render Targets", 400, 400, ES_WINDOW_RGB | ES_WINDOW_ALPHA );
+
+   if ( !Init ( esContext ) )
+   {
+      return GL_FALSE;
+   }
+
+   esRegisterDrawFunc ( esContext, Draw );
+   esRegisterShutdownFunc ( esContext, ShutDown );
+
+   return GL_TRUE;
+}