Offscreen buffer stuff

cOffScreenBuffer.cpp

/*
 *  offscrbuffer.cpp
 *  gazotron
 *
 *  Created by Gary Liddon on 23/08/2006.
 *  Copyright 2006 __MyCompanyName__. All rights reserved.
 *
 */

#include "cOffScreenBuffer.h"

#include <stdio.h>
#include <glib/include/gdebug.h>
namespace core
{
	cOffScreenBuffer::cOffScreenBuffer(int _width, int _height, bool _hasZ)
	{
		// This routine creates a frame buffer object (FBO)
		// and then binds a texture to it as a logical buffer for drawing to
		// and if there's a Z buffer required
		// creates a render buffer and then attaches it to the FBO as a depth
		// buffer
		
		
		glGenTextures(1, &mColorTex);
		
		// Get an unused FB object
		glGenFramebuffersEXT(1, &mFb);
		
		/* Select this frame buffer as the current context */
		glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, mFb);
		
		
		/* Now create a texture for the buffer to work with */
		
		glBindTexture(GL_TEXTURE_2D, mColorTex);
		
		glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
		glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
		glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP );
		glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP );
		
		
		
		glTexImage2D(GL_TEXTURE_2D, 0, 4, _width, _height, 0,
					 GL_RGBA, GL_FLOAT, NULL);
		
		/* Make this texture the logical drawing buffer for the current context */
		glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT,
								  GL_COLOR_ATTACHMENT0_EXT,
								  GL_TEXTURE_2D, mColorTex, 0);
		
		
		// Create a render buffer for the depth buffer and the attach it
		// to the current context if we want one
		
		if (_hasZ)
		{
			glGenRenderbuffersEXT(1, &mDepthRb);
			
			glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, mDepthRb);
			
			glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT,
									 GL_DEPTH_COMPONENT24, _width, _height);
			
			glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT,
										 GL_DEPTH_ATTACHMENT_EXT,
										 GL_RENDERBUFFER_EXT, mDepthRb);
		}
		
		// Check framebuffer completeness at the end of initialization.
		
		GLenum status;
		status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT);
		
		switch(status)
		{
			case GL_FRAMEBUFFER_COMPLETE_EXT:
				break;
				
			case GL_FRAMEBUFFER_UNSUPPORTED_EXT:
				ASSERT(0);
				break;
			default:
				/* programming error; will fail on all hardware */
				ASSERT(0);
				break;
		}
		
		mWidth = _width;
		mHeight = _height;
		
		useBuffer();
		glClearColor(0,0,0,1);
		
			glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
		
		discardBuffer();
		
	}
	
	GLuint cOffScreenBuffer::texture(void)
	{
		return (mColorTex);
	}
	
	void cOffScreenBuffer::useBuffer(void)
	{
		glViewport(0,0,mWidth, mHeight);
		glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, mFb);
	}
	
	
	void cOffScreenBuffer::discardBuffer()
	{
		glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
	}
	
	
	
}

cOffScreenBuffer.h

/*
 *  offscrbuffer.h
 *  gazotron
 *
 *  Created by Gary Liddon on 23/08/2006.
 *  Copyright 2006 __MyCompanyName__. All rights reserved.
 *
 */

#ifndef __OFFSCRBUFFER_H__
#define __OFFSCRBUFFER_H__

#include <core/glutils.h>
#include <core/render/cTexture.h>

namespace core
{
	class cOffScreenBuffer
	{
	public:
		cOffScreenBuffer(int _width, int _height, bool _hasZ = false);
		
		virtual ~cOffScreenBuffer()
		{
		}
		
		
		GLuint	texture(void);
		
		virtual void useBuffer();
		
		void discardBuffer();
		
		unsigned int getWidth(void)  const
		{	return (mWidth);	}
		
		unsigned int getHeight(void)  const
		{	return (mHeight);	}
		
		GLuint getFrameBufferObject(void) const
		{
			return mFb;
		}
		
		cTexture getcTexture(void) const
		{
			return (cTexture(mColorTex, mWidth, mHeight));
		}
		
	protected:
		
		GLuint	mFb;
		GLuint	mDepthRb;
		GLuint	mColorTex;
		
		unsigned int	mWidth, mHeight;
		
	};
	
}


#endif /* __OFFSCRBUFFER_H__ */