libj/J/fbo.h

//
//  fbo.h
//  J
//
//  Created by Joshua Moerman on 7/01/11.
//  Copyright 2011 Vadovas. All rights reserved.
//

#ifndef FBO_H
#define FBO_H

#include <map>
#include <iostream>
#include <stdexcept>
#include "to_string.h"

#include "basic.h"

@class EAGLContext;
@class CAEAGLLayer;


// TODO: more error checking in debug build.
// TODO: make texture class? for easier switching between linear/nearest interpolation for example
// NOTE: stencil attachment is not supported

namespace J {

class fbo {
public:
    typedef std::map<GLenum, GLuint> RenderbuffersMap;
    
	int width, height;
	GLuint fbo_number;
	RenderbuffersMap renderbuffers;
	GLuint texture_id;

public:
    // standard ctor, makes use of textures
	fbo(int width, int height) : width(width), height(height), fbo_number(0), renderbuffers(), texture_id(0) {
		glGenFramebuffers(1, &fbo_number);
		bind();

		// generate texture
		glGenTextures(1, &texture_id);
		glBindTexture(GL_TEXTURE_2D, texture_id);
		glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
		glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture_id, 0);

		// attach depth
		create_attach_renderbuffer(GL_DEPTH_COMPONENT16, GL_DEPTH_ATTACHMENT);
        
		check_error();
		check_status();

		glClearColor(0.0, 0.0, 0.0, 0.0);
		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

		unbind();
	}
    
    // ctor from EAGLContext, not using texture, so you cannot use it as lookup, only as renderer.
    fbo(EAGLContext* context, CAEAGLLayer* layer);
    
	~fbo() {
		end();

		glDeleteFramebuffers(1, &fbo_number);

		for(RenderbuffersMap::const_iterator i = renderbuffers.begin(); i != renderbuffers.end(); ++i){
            RenderbuffersMap::value_type const & it = *i;
			glDeleteRenderbuffers(1, &it.second);
		}
        
        glDeleteTextures(1, &texture_id);
        // NOTE: glDeleteTextures silently ignores 0's and names that do not correspond to existing textures.
	}

	void begin(){
		bind();
        // FIXME: this should be done, but also switching back should be done...
		//glPushAttrib(GL_VIEWPORT);
		glViewport(0, 0, width, height);

        // NOTE: commented out, because we don't want fbo's to nest.
		/*GLint savedFramebuffer = -1;
		glGetIntegerv(GL_FRAMEBUFFER_BINDING, &savedFramebuffer);
		std::cout << "sfb: " << savedFramebuffer << ", fbo: " << fbo_number << std::endl;*/
	}

	void end(){
		unbind();
        // FIXME: switch back to previous viewport. See begin()
		//glPopAttrib();
	}

	void bind(){
		glBindFramebuffer(GL_FRAMEBUFFER, fbo_number);
		check_error();
	}

	void unbind(){
		glBindFramebuffer(GL_FRAMEBUFFER, 0);
	}
    
private:
	void create_attach_renderbuffer(GLenum format, GLenum attachment_point) {
		GLuint buffer;
		glGenRenderbuffers(1, &buffer);
		glBindRenderbuffer(GL_RENDERBUFFER, buffer);
		glRenderbufferStorage(GL_RENDERBUFFER, format, width, height);
		glFramebufferRenderbuffer(GL_FRAMEBUFFER, attachment_point, GL_RENDERBUFFER, buffer);

		renderbuffers[format] = buffer;
	}

	void check_status() {
        #if defined(DEBUG)
		GLenum status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
		switch(status) {
		case GL_FRAMEBUFFER_COMPLETE:
			std::cout << "FRAMEBUFFER_COMPLETE - OK" << std::endl;
			return;
		case GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT:
			std::cout << "FRAMEBUFFER_INCOMPLETE_ATTACHMENT" << std::endl;
			break;
		case GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT:
			std::cout << "FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT" << std::endl;
			break;
		case GL_FRAMEBUFFER_INCOMPLETE_DIMENSIONS:
			std::cout << "FRAMEBUFFER_INCOMPLETE_DIMENSIONS" << std::endl;
			break;
		case GL_FRAMEBUFFER_UNSUPPORTED:
			std::cout << "FRAMEBUFFER_UNSUPPORTED" << std::endl;
			break;
		default:
			std::cout << "UNKNOWN FRAMEBUFFER ERROR" << std::endl;
			break;
		}
		throw std::runtime_error("I will not continu..");
        #endif
	}

};
    
} // namespace J

#endif // FBO_H