v002FBO.m

//
//  v002FBO.m
//  v002Blurs
//
//  Created by vade on 4/8/09.
//  Copyright 2009 __MyCompanyName__. All rights reserved.
//

#import "v002FBO.h"

// macro for speed
#import <OpenGL/CGLMacro.h>

@implementation v002FBO


- (id) initWithContext:(CGLContextObj)cgl_ctx
{
    self = [super init];
	if (self)
	{
	
		context = cgl_ctx;
		CGLRetainContext(context);
        
		// this pushes texture attributes
		[self pushAttributes:cgl_ctx];
		// since we are using FBOs we ought to keep track of what was previously bound
		[self pushFBO:cgl_ctx];
		
		// faux bounds for now, for testing to init our FBO		
		
		// init a temporary texture to test FBO support
		GLuint textureID;
		glGenTextures(1, &textureID);
        glEnable(GL_TEXTURE_RECTANGLE_ARB);
		glBindTexture(GL_TEXTURE_RECTANGLE_ARB, textureID);
		
		glTexImage2D(GL_TEXTURE_RECTANGLE_ARB, 0, GL_RGBA8, 640U, 480U, 0, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, NULL);
        glBindTexture(GL_TEXTURE_RECTANGLE_ARB, 0);
        
		// Create FBO 
		glGenFramebuffers(1, &fboID);
		glBindFramebuffer(GL_FRAMEBUFFER, fboID);
		glFramebufferTexture2DEXT(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_RECTANGLE_ARB, textureID, 0);
		
		GLenum status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
		glDeleteTextures(1, &textureID);
		// restore state
		[self popFBO:cgl_ctx];
		[self popAttributes:cgl_ctx];
		if(status != GL_FRAMEBUFFER_COMPLETE)
        {
#if !__has_feature(objc_arc)
            [self release];
#endif
           self = nil;
		}
	}
	
	return self;
}

- (void)cleanupGL
{
	CGLContextObj cgl_ctx = context;
	CGLLockContext(cgl_ctx);
	if (fboID) glDeleteFramebuffers(1, &fboID);
	CGLUnlockContext(cgl_ctx);	
	
	CGLReleaseContext(context);
}

- (void) dealloc
{
	[self cleanupGL];
#if !__has_feature(objc_arc)
	[super dealloc];
#endif
}

- (void) pushFBO:(CGLContextObj)cgl_ctx
{	
	glGetIntegerv(GL_FRAMEBUFFER_BINDING, &previousFBO);
	glGetIntegerv(GL_READ_FRAMEBUFFER_BINDING, &previousReadFBO);
	glGetIntegerv(GL_DRAW_FRAMEBUFFER_BINDING, &previousDrawFBO);
	
//	NSLog(@"Pushing FBO: previous FBO: %i", previousFBO);
//	NSLog(@"Pushing FBO: previous FBO Draw: %i", previousDrawFBO);
//	NSLog(@"Pushing FBO: previous FBO Read: %i", previousReadFBO);
}

- (void) popFBO:(CGLContextObj)cgl_ctx
{
	glBindFramebufferEXT(GL_FRAMEBUFFER, previousFBO);
	glBindFramebufferEXT(GL_READ_FRAMEBUFFER, previousReadFBO);
	glBindFramebufferEXT(GL_DRAW_FRAMEBUFFER, previousDrawFBO);
}

- (void)pushAttributes:(CGLContextObj)cgl_ctx
{
	// save our current GL state - balanced in detachFBO method
	glPushAttrib(GL_ALL_ATTRIB_BITS);
}

- (void)popAttributes:(CGLContextObj)cgl_ctx
{
	// restore states // assume this is balanced with above 
	glPopAttrib();
}

- (void) attachFBO:(CGLContextObj)cgl_ctx withTexture:(GLuint)tex width:(GLsizei)width height:(GLsizei)height
{
    [self bindFBO:cgl_ctx];
    [self attachFBO:cgl_ctx withTexture:tex toAttachment:GL_COLOR_ATTACHMENT0 width:width height:height];
    [self setupFBOViewport:cgl_ctx width:width height:height];
}

- (void) bindFBO:(CGLContextObj)cgl_ctx
{
    glBindFramebuffer(GL_FRAMEBUFFER, fboID);
}

- (void) setupFBOViewport:(CGLContextObj)cgl_ctx width:(GLsizei)width height:(GLsizei)height
{
    glViewport(0, 0,  width, height);
    glMatrixMode(GL_PROJECTION);
    glPushMatrix();
    glLoadIdentity();
    
    glOrtho(0.0, width,  0.0,  height, -1, 1);
    
    glMatrixMode(GL_MODELVIEW);
    glPushMatrix();
    glLoadIdentity();
    
    // client now renders to our quad...
}

- (void) attachFBO:(CGLContextObj)cgl_ctx withTexture:(GLuint)tex toAttachment:(GLuint)attachment width:(GLsizei)width height:(GLsizei)height
{
	// bind our FBO
	glFramebufferTexture2D(GL_FRAMEBUFFER, attachment, GL_TEXTURE_RECTANGLE_ARB, tex, 0);

	// Assume FBOs JUST WORK, because we checked on startExecution	

	// Setup OpenGL states 
	// this may be an issue... ?
}

- (void ) detachFBO:(CGLContextObj) cgl_ctx
{
	// Restore OpenGL states 
	glMatrixMode(GL_MODELVIEW);
	glPopMatrix();
	glMatrixMode(GL_PROJECTION);
	glPopMatrix();
    
    // The following line should be up to callers if they need it
    // not us but I'm leaving it now because it will probably break
    // other code if I remove it... Tom
	glFlushRenderAPPLE();
}


@end