FBO.c

/* 
**	FBO.c 
**
**	Copyright (c) 2008 Max Rupp (feelgood@cs.pdx.edu) All rights reserved.
**
**	cc FBO.c -o FBO -Wall -std=c99 -DDEBUG -DW=640 -DH=480 -framework OpenGL -framework GLUT
*/

#include <OpenGL/OpenGL.h>
#include <GLUT/glut.h>
#include <stdio.h>

#include "error.h"

GLuint T[10];

static GLvoid 
display( GLvoid )
{                		
	/* ... */
	{
		glBindFramebufferEXT( GL_FRAMEBUFFER_EXT, T[3] );
		{	
			glUseProgram(                  T[4] );
			glBindBuffer( GL_ARRAY_BUFFER, T[0] );																															

			glDrawArrays( GL_TRIANGLE_STRIP, 0, 4 ); 				

			eglGetError( );
		}
		
		glBindFramebufferEXT( GL_FRAMEBUFFER_EXT, 0 );
		{		
			glUseProgram (                  T[5] );
			glBindBuffer ( GL_ARRAY_BUFFER, T[1] );																															
			glBindTexture( GL_TEXTURE_2D,   T[2] );

			glDrawArrays( GL_TRIANGLE_STRIP, 0, 4 ); 				

			glFlush( );

			eglGetError( );
		}
	}
} 

static GLvoid
reshape( const GLint X, const GLint Y )
{
	/* ... */
	{
		glViewport( 0, 0, X, Y ); 
		
		glTexImage2D( GL_TEXTURE_2D, 0, GL_RGBA8, X, Y, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL );

		eglGetError( );
	}
}

static GLvoid 
init( GLvoid )
{
	/* ... */
	{
		glGenBuffers        ( 2, &T[0] );
		glGenTextures       ( 1, &T[2] );
		glGenFramebuffersEXT( 1, &T[3] );
	
		T[4] = glCreateProgram( ); T[6] = glCreateShader( GL_VERTEX_SHADER ); T[7] = glCreateShader( GL_FRAGMENT_SHADER );
		T[5] = glCreateProgram( ); T[8] = glCreateShader( GL_VERTEX_SHADER ); T[9] = glCreateShader( GL_FRAGMENT_SHADER );

		eglGetError( );
	}
	
	/* ... */
	{
		glDisable( GL_DITHER );
	}
	
	/* ... */
	{
		const GLfloat A[] = 
		{ 
			-1.0f, -1.0f, 1.0f, -1.0f, -1.0f, 1.0f, 1.0f, 1.0f, 
			 1.0f,  0.0f, 0.0f,  1.0f,  0.0f, 1.0f, 0.0f, 1.0f, 
			 0.0f,  0.0f, 1.0f,  1.0f,  0.0f, 0.0f, 0.0f, 1.0f 
		};

		const GLfloat B[] = 
		{ 
			-1.0f, -1.0f, 1.0f, -1.0f, -1.0f, 1.0f, 1.0f, 1.0f, 
			 0.0f,  1.0f, 1.0f,  1.0f,  0.0f, 0.0f, 1.0f, 0.0f 
		};	
		
		glBindBuffer( GL_ARRAY_BUFFER, T[0] );																															
		glBufferData( GL_ARRAY_BUFFER, sizeof( A ), A, GL_STATIC_DRAW );																							
																																											
		glEnableVertexAttribArray( 0 ); glVertexAttribPointer( 0, 2, GL_FLOAT, GL_FALSE, 0, ( const GLvoid * ) ( sizeof( GLfloat ) * 0 ) );
		glEnableVertexAttribArray( 1 ); glVertexAttribPointer( 1, 4, GL_FLOAT, GL_FALSE, 0, ( const GLvoid * ) ( sizeof( GLfloat ) * 8 ) );

		eglGetError( );

		glBindBuffer( GL_ARRAY_BUFFER, T[1] );																															
		glBufferData( GL_ARRAY_BUFFER, sizeof( B ), B, GL_STATIC_DRAW );																							
																																											
		glEnableVertexAttribArray( 2 ); glVertexAttribPointer( 2, 2, GL_FLOAT, GL_FALSE, 0, ( const GLvoid * ) ( sizeof( GLfloat ) * 0 ) );
		glEnableVertexAttribArray( 3 ); glVertexAttribPointer( 3, 2, GL_FLOAT, GL_FALSE, 0, ( const GLvoid * ) ( sizeof( GLfloat ) * 8 ) );

		eglGetError( );
	}
	
	/* ... */
	{a
		glBindTexture       ( GL_TEXTURE_2D,      T[2] );
		glBindFramebufferEXT( GL_FRAMEBUFFER_EXT, T[3] );

		glTexParameteri     ( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR        );
		glTexParameteri     ( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR        );
		glTexParameteri     ( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S,     GL_CLAMP_TO_EDGE );
		glTexParameteri     ( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T,     GL_CLAMP_TO_EDGE );
		
		glTexImage2D( GL_TEXTURE_2D, 0, GL_RGBA8, W, H, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL );

		glFramebufferTexture2DEXT( GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_2D, T[2], 0 );
	
		eglCheckFramebufferStatus( );
	}

	/* ... */
	{
		const GLfloat M[] = 
		{
			1.0f, 0.0f, 0.0f, 0.0f, 0.0f,  1.0f, 0.0f, 0.0f, 
			0.0f, 0.0f, 1.0f, 0.0f, 0.0f,  0.0f, 0.0f, 1.0f, 

			1.0f, 0.0f, 0.0f, 0.0f, 0.0f, -1.0f, 0.0f, 0.0f, 
			0.0f, 0.0f, 1.0f, 0.0f, 0.0f,  0.0f, 0.0f, 1.0f 
		};

		const GLchar *S[4] = 
		{ 
			"attribute vec4 A0; attribute vec4 A1; varying vec4 V0; uniform mat4 M0; void main( void ) { V0 = A1; gl_Position = ( M0 * A0 ); }",
			"attribute vec4 A0; attribute vec2 A1; varying vec2 V0; uniform mat4 M0; void main( void ) { V0 = A1; gl_Position = ( M0 * A0 ); }", 
							   
			"varying vec4 V0;                       void main( void ) { gl_FragColor = V0;                  }",
			"varying vec2 V0; uniform sampler2D S0; void main( void ) { gl_FragColor = texture2D( S0, V0 ); }" 
		};

		glShaderSource( T[6], 1, &S[0], NULL ); glCompileShader( T[6] ); eglGetShaderInfoLog( T[6], S[0] ); glAttachShader( T[4], T[6] );
		glShaderSource( T[7], 1, &S[2], NULL ); glCompileShader( T[7] ); eglGetShaderInfoLog( T[7], S[2] ); glAttachShader( T[4], T[7] ); 
		
		glBindAttribLocation( T[4], 0, "A0" );
		glBindAttribLocation( T[4], 1, "A1" );
		glLinkProgram       ( T[4]          );	
		glUseProgram        ( T[4]          ); glUniformMatrix4fv( glGetUniformLocation( T[4], "M0" ), 1, GL_FALSE, ( M + 0  ) );																		

		eglGetError( );
		
		glShaderSource( T[8], 1, &S[1], NULL ); glCompileShader( T[8] ); eglGetShaderInfoLog( T[8], S[1] ); glAttachShader( T[5], T[8] );
		glShaderSource( T[9], 1, &S[3], NULL ); glCompileShader( T[9] ); eglGetShaderInfoLog( T[9], S[3] ); glAttachShader( T[5], T[9] ); 

		glBindAttribLocation( T[5], 2, "A0" );
		glBindAttribLocation( T[5], 3, "A1" );
		glLinkProgram       ( T[5]          );	
		glUseProgram        ( T[5]          ); glUniformMatrix4fv( glGetUniformLocation( T[5], "M0" ), 1, GL_FALSE, ( M + 16 ) );																		

		eglGetError( );
	}
}
 
int 
main( int argc, char **argv )
{
	glutInit( &argc, argv );
	glutInitDisplayString( "single rgba" );
	glutInitWindowSize( W, H );
	glutInitWindowPosition( 0, 0 );
	glutCreateWindow( "FBO" );
	glutDisplayFunc( display );
	glutReshapeFunc( reshape );
	
	init( );

	glutMainLoop( );
	
	return 0;
}