gistfile1.m

@interface ChipmunkSprite : CCSprite {
	ChipmunkBody *body;
	cpBody *cp_body;
}

@property(retain) ChipmunkBody *body;

@end




@implementation ChipmunkSprite

- (ChipmunkBody *)body {return body;}

-(void)setBody:(ChipmunkBody *)newBody {
	ChipmunkBody *oldBody = body;
	
	body = [newBody retain];
	cp_body = body.body;
	
	[oldBody release];
}

- (CGPoint)position {return cp_body->p;}

- (void)setPosition:(CGPoint)p {
	position_ = cp_body->p = p;
}

- (float)rotation {return -CC_RADIANS_TO_DEGREES(cp_body->a);}

- (void)setRotation:(float)a {
	rotation_ = a;
	cpBodySetAngle(cp_body, -CC_DEGREES_TO_RADIANS(a));
}

-(BOOL)dirty {return TRUE;}

static inline void update(ChipmunkSprite *sprite){
	assert(sprite->cp_body);
	
	sprite->rotation_ = CC_RADIANS_TO_DEGREES(-sprite->cp_body->a);
	sprite->position_ = sprite->cp_body->p;
}

-(void)updateTransform {
	update(self);
	[super updateTransform];
}

-(void)visit {
	update(self);
	[super visit];
}

// making a private copy of the struct definition is not ideal, but works to prove the point
struct transformValues_ {
	CGPoint pos;		// position x and y
	CGPoint	scale;		// scale x and y
	float	rotation;
	CGPoint ap;			// anchor point in pixels
};

-(struct transformValues_)getTransformValues {
	return (struct transformValues_){
		cp_body->p,
		{scaleX_, scaleY_},
		-CC_RADIANS_TO_DEGREES(cp_body->a),
		anchorPointInPixels_
	};
}


@end