GFFParallaxNode

GFFParallaxNode.h

//
//  GFFParallaxNode.h
//
//  Created by Rolando Abarca on 12/14/09.
//

#import <Foundation/Foundation.h>
#import "cocos2d.h"

#define MAX_PARALLAX_CHILDREN 25

@interface GFFParallaxNode : CocosNode {
	float ratios[MAX_PARALLAX_CHILDREN];
	int childrenNo;
}
- (void)addChild:(CocosNode *)child z:(int)z parallaxRatio:(float)ratio;
- (void)scroll:(float)offset;
@end

GFFParallaxNode.mm

//
//  GFFParallaxNode.m
//
//  Created by Rolando Abarca on 12/14/09.
//

#import "GFFParallaxNode.h"
#import "RepeatableLayer.h"

@implementation GFFParallaxNode
- (id)init {
	if ((self = [super init])) {
		childrenNo = 0;
	}
	return self;
}

- (void)addChild:(RepeatableLayer *)child z:(int)z parallaxRatio:(float)ratio {
	NSAssert(childrenNo < MAX_PARALLAX_CHILDREN, @"Reached max of parallax children!");
	ratios[childrenNo++] = ratio;

	[super addChild:child z:z];
}

- (void)scroll:(float)offset {
	int idx = 0;
	for (RepeatableLayer *child in children) {
		[child scroll:offset * ratios[idx++]];
	}
}

- (void)scrollTest {
	[self scroll:0.3f];
}
@end

RepeatableLayer.h

//
//  RepeatableLayer.h
//
//  Created by Rolando Abarca on 12/13/09.
//

#import <Foundation/Foundation.h>
#import "cocos2d.h"

@interface RepeatableLayer : Sprite {
	CGPoint texOffset;
	CGPoint firstOffset;
}
+ (id)layerWithFile:(NSString *)file;
- (void)scrollTest;
- (void)scroll:(float)offset;
@end

RepeatableLayer.mm

//
//  RepeatableLayer.mm
//
//  Created by Rolando Abarca on 12/13/09.
//

#import "RepeatableLayer.h"


@implementation RepeatableLayer
+ (id)layerWithFile:(NSString *)file {
	RepeatableLayer *layer = [RepeatableLayer spriteWithFile:file];
	layer.anchorPoint = CGPointZero;
	ccTexParams params = { GL_LINEAR, GL_LINEAR, GL_REPEAT, GL_REPEAT };
	[layer.texture setTexParameters:&params];
	return layer;
}

- (void)draw {
	glEnableClientState( GL_VERTEX_ARRAY); 
	glEnableClientState( GL_TEXTURE_COORD_ARRAY ); 
	glEnable( GL_TEXTURE_2D); 
	glColor4ub( color_.r, color_.g, color_.b, opacity_); 
	//Adjust the texture matrix 
	glMatrixMode(GL_TEXTURE); 
	glPushMatrix(); 
	glLoadIdentity(); 
	//We are just doing horizontal scrolling here so only adjusting x 
	glTranslatef(texOffset.x/self.contentSize.width, 0, 0); 
	//Draw the texture 
	[texture_ drawAtPoint:CGPointZero]; 
	//Restore texture matrix and switch back to modelview matrix 
	glPopMatrix(); 
	glMatrixMode(GL_MODELVIEW); 
	glColor4ub( 255, 255, 255, 255); 
	glDisable( GL_TEXTURE_2D); 
	glDisableClientState(GL_VERTEX_ARRAY ); 
	glDisableClientState( GL_TEXTURE_COORD_ARRAY ); 
}

//
// adapted from
// http://www.codza.com/making-seamless-repeating-backgrounds-photoshop-cocos2d-iphone
// 
// it only scrolls on x-axis
//
- (void)scroll:(float)offset {
	texOffset = ccpAdd(texOffset, CGPointMake(offset, 0.0f));
	CGSize contentSize = texture_.contentSize;
	if (texOffset.x > contentSize.width) texOffset.x -= contentSize.width;
	if (texOffset.y > contentSize.height) texOffset.y -= contentSize.height;
	if (texOffset.x < 0) texOffset.x += contentSize.width;
	if (texOffset.y < 0) texOffset.y += contentSize.height;
}

- (void)scrollTest {
	[self scroll:0.3f];
}
@end