Aaron Goselin Aaron Goselin - 4 months ago 21
iOS Question

CCParallaxNode parallaxRatio (explanation)

I feel stupid asking this question, but I can not find a clear answer anywhere (or much of an answer at all) so I feel I must ask. Is there anyone out there who can explain clearly how the parallaxRatio of CCParallaxNode works?

I have checked the source of CCParallaxNode and it does not explain it at all. I have searched the internet and stackOverflow extensively. I have tried to do good old trial and error. I'm still confused.

[parallaxLayer addChild:backgroundEffect_subtleRed z:100 parallaxRatio:ccp(0.5, 0.5) positionOffset:backgroundEffect_subtleRed.position];


In this piece of code I am trying to add a particle emitter to a parallaxLayer and have it move somewhat like you would expect an object on a parallax layer to move. Unfortunately I do not see the particles at all. I have had this problem anytime I try to add anything to a parallaxNode when I want it to move. I have been using CCParallaxNode to create static UI layers, but have not been able to use them for what they were built to do.

In summary:

parallaxRatio takes a CGPoint. What do the floats in the CGPoint apply to? Are they ratios of x and y in relation to the window? Are they (parallaxLayerMovementInRelationTo, parentNode)? A working piece of example code would be very helpful.

Thank you.

Answer

To quote from a cocos2d book I own:

[paraNode addChild:para1 z:1 parallaxRatio:CGPointMake(0.5f, 0) positionOffset:topOffset];
    [paraNode addChild:para2 z:2 parallaxRatio:CGPointMake(1, 0) positionOffset:topOffset];
    [paraNode addChild:para3 z:4 parallaxRatio:CGPointMake(2, 0) positionOffset:midOffset];
    [paraNode addChild:para4 z:3 parallaxRatio:CGPointMake(3, 0) positionOffset:downOffset];

"The CCParallaxNode is created like any other node, but its children are added using a special initializer. With it you specify the parallax ratio, which is a CGPoint used as a multiplier for any movement of the CCParallaxNode In this case, para1 would move at half the speed, para2 at the normal speed, para3 at double the speed of the CCParallaxNode, and so on"

So basically, its the ratio that the individual layers are moved in the relation to the movement of the whole CCParallaxNode.