~~NOTOC~~

====== BEParallaxSprite ======

---- dataentry extension ----
type          : extension
author_mail   : briancensor@gmail.com Brian Ensor 
description   : A simple parallax background sprite.
lastupdate_dt : 2011-01-29
compatible    : v1.1
depends       : 
tags          : parallax, scrolling, background, layers
homepage_url  : https://github.com/brianensorapps/BEParallaxSprite
download_url  : https://github.com/brianensorapps/BEParallaxSprite/zipball/master
----
\\ [[/users/brian/start|My Wiki Page]]
\\
===== Usage =====

{{http://img860.imageshack.us/img860/784/screenshot20110313at114.png|}}

<code objc>
sky = [BEParallaxSprite parallexSpriteWithTexture:[SPTexture textureWithContentsOfFile:@"sky.png"] speed:0.5 direction:BE_PARALLAX_DIRECTION_LEFT];
[self addChild:sky];
</code>

===== Changelog =====

  * 2011/01/23: First public version
  * 2011/01/29: Added start and stop methods
===== Source Code =====

BEParallaxSprite.h
<code objc>
#import <Foundation/Foundation.h>

#define BE_PARALLAX_DIRECTION_LEFT 1
#define BE_PARALLAX_DIRECTION_RIGHT 2
#define BE_PARALLAX_DIRECTION_UP 3
#define BE_PARALLAX_DIRECTION_DOWN 4

@interface BEParallaxSprite : SPSprite {
	SPImage *mImage1;
	SPImage *mImage2;
	float mSpeed;
	int mDirection;
	float mCurStep;
	bool mRunning;
}

@property (nonatomic, assign) bool running;
@property (nonatomic, assign) float speed;

- (void)onEnterFrame:(SPEnterFrameEvent *)event;
- (void)start;
- (void)stop;
- (id)initWithTexture:(SPTexture *)texture;
- (id)initWithTexture:(SPTexture *)texture speed:(float)speed;
- (id)initWithTexture:(SPTexture *)texture speed:(float)speed direction:(int)direction;
+ (BEParallaxSprite *)parallexSpriteWithTexture:(SPTexture *)texture;
+ (BEParallaxSprite *)parallexSpriteWithTexture:(SPTexture *)texture speed:(float)speed;
+ (BEParallaxSprite *)parallexSpriteWithTexture:(SPTexture *)texture speed:(float)speed direction:(int)direction;

@end
</code>
BEParallaxSprite.m
<code objc>
#import "BEParallaxSprite.h"

@implementation BEParallaxSprite

@synthesize speed = mSpeed;
@synthesize running = mRunning;

- (id)initWithTexture:(SPTexture *)texture {
	if (self = [super init]) {
		[self initWithTexture:texture speed:1 direction:BE_PARALLAX_DIRECTION_LEFT];
	}
	return self;
}

- (id)initWithTexture:(SPTexture *)texture speed:(float)speed {
	if (self = [super init]) {
		[self initWithTexture:texture speed:speed direction:BE_PARALLAX_DIRECTION_LEFT];
	}
	return self;
}

- (id)initWithTexture:(SPTexture *)texture speed:(float)speed direction:(int)direction {
	if (self = [super init]) {
		mRunning = YES;
		mDirection = direction;
		if (direction < 1 || direction > 4) {
			mDirection = BE_PARALLAX_DIRECTION_LEFT;
		}
		mSpeed = speed;
		mImage1 = [SPImage imageWithTexture:texture];
		[self addChild:mImage1];
		mImage2 = [SPImage imageWithTexture:texture];
		if (mDirection == BE_PARALLAX_DIRECTION_DOWN) {
			mImage2.y = mImage1.y-mImage2.height;
		}
		if (mDirection == BE_PARALLAX_DIRECTION_UP) {
			mImage2.y = mImage1.y+mImage1.height;
		}
		if (mDirection == BE_PARALLAX_DIRECTION_RIGHT) {
			mImage2.x = mImage1.x-mImage2.width;
		}
		if (mDirection == BE_PARALLAX_DIRECTION_LEFT) {
			mImage2.x = mImage1.x+mImage1.width;
		}
		[self addChild:mImage2];
		[self addEventListener:@selector(onEnterFrame:) atObject:self forType:SP_EVENT_TYPE_ENTER_FRAME];
	}
    return self;
}

+ (BEParallaxSprite *)parallexSpriteWithTexture:(SPTexture *)texture {
	return [[[BEParallaxSprite alloc] initWithTexture:texture speed:1 direction:BE_PARALLAX_DIRECTION_LEFT] autorelease];
}

+ (BEParallaxSprite *)parallexSpriteWithTexture:(SPTexture *)texture speed:(float)speed {
	return [[[BEParallaxSprite alloc] initWithTexture:texture speed:speed direction:BE_PARALLAX_DIRECTION_LEFT] autorelease];
}

+ (BEParallaxSprite *)parallexSpriteWithTexture:(SPTexture *)texture speed:(float)speed direction:(int)direction {
	return [[[BEParallaxSprite alloc] initWithTexture:texture speed:speed direction:direction] autorelease];
}

- (void)start {
	if (mRunning != YES) {
		mRunning = YES;
	}
}

- (void)stop {
	if (mRunning != NO) {
		mRunning = NO;
	}
}

- (void)onEnterFrame:(SPEnterFrameEvent *)event {
	if (mRunning == YES) {
		mCurStep += mSpeed;
		if (mCurStep < 1) return;
		if (mDirection == BE_PARALLAX_DIRECTION_DOWN) {
			mImage1.y += floor(mCurStep);
			mImage2.y += floor(mCurStep);
			if (mImage1.y >= mImage1.height) {
				mImage1.y = mImage2.y-mImage2.height;
			}
			if (mImage2.y >= mImage2.height) {
				mImage2.y = mImage1.y-mImage1.height;
			}
		}
		if (mDirection == BE_PARALLAX_DIRECTION_UP) {
			mImage1.y -= floor(mCurStep);
			mImage2.y -= floor(mCurStep);
			if (mImage1.y <= -mImage1.height) {
				mImage1.y = mImage2.y+mImage2.height;
			}
			if (mImage2.y <= -mImage2.height) {
				mImage2.y = mImage1.y+mImage1.height;
			}
		}
		if (mDirection == BE_PARALLAX_DIRECTION_RIGHT) {
			mImage1.x += floor(mCurStep);
			mImage2.x += floor(mCurStep);
			if (mImage1.x >= mImage1.width) {
				mImage1.x = mImage2.x-mImage2.width;
			}
			if (mImage2.x >= mImage2.width) {
				mImage2.x = mImage1.x-mImage1.width;
			}
		}
		if (mDirection == BE_PARALLAX_DIRECTION_LEFT) {
			mImage1.x -= floor(mCurStep);
			mImage2.x -= floor(mCurStep);
			if (mImage1.x <= -mImage1.width) {
				mImage1.x = mImage2.x+mImage2.width;
			}
			if (mImage2.x <= -mImage2.width) {
				mImage2.x = mImage1.x+mImage1.width;
			}
		}
		mCurStep -= floor(mCurStep);
	}
}

- (void)dealloc {
	[super dealloc];
}

@end
</code>

If using Xcode 4 and the latest sparrow release, remember to include "libz.dylib" in your project.
It took me a lot of time to track down it was missing, causing linker errors.