Rotating CocosNode's Children « cocos2d for iPhone

cocos2d for iPhone » Programming » cocos2d support (graphics engine)

Rotating CocosNode's Children

(10 posts) (5 voices)

Started 2 years ago by sachmoz
Latest reply from coolman

Tags:

sachmoz
Member

Hi,

I have a subclass of CocosNode called "PlayerShip" that has a Sprite as a child. If I set an anchorPoint on the PlayerShip class and then try to rotate it, the sprite rotates about it's centre, rather than the anchor point that I set on PlayerShip. Is this correct behaviour as it goes against my expectations for what should happen?

I can see that this is happening because the setter for anchorPoint multiplies the normalised anchorPoint by the content size or PlayerShip. But the content size of PlayerShip is 0 for both width and height.

I'm currently using version 8.0 beta.

Thanks.

Posted 2 years ago #
Codemattic
Moderator

anchorPoint is now (unfortunately IMHO) a percentage. Maybe in your subclass call setContentSize to whatever the combined sizes of its children is - and then set anchor point?

Posted 2 years ago #
sachmoz
Member

It does seem a bit inconvenient with the way that it works now, especially if you want to rotate around a point that is outside the bounds of the object you are rotating. However, I'll try your suggestion.

Thanks for your help.

Posted 2 years ago #
Codemattic
Moderator

"rotate around a point that is outside the bounds of the object you are rotating."

just fyi - you arent limited to coordinates between 0.0 and 1.0. You could make it (2.0, 2.0) to make the anchorPoint set outside the bounds. But I agree absolute positioning seems more natural, imho.

Posted 2 years ago #
coolman
Member

>is now (unfortunately IMHO) a percentage

That seems wierd. A percentage of what?

Posted 2 years ago #
Codemattic
Moderator

(0.5, 0.5) will always be the center of the sprite. Its a percentage wrt size.

Posted 2 years ago #
coolman
Member

I see. Well now we have less control from the anchorpoint

Posted 2 years ago #
crmagicxxx
Member
I see. Well now we have less control from the anchorpoint

Not really true...
You can still have whatever coordinates you want with new anchorPoint, Riq explained it many times:
For example, if you want your anchor at cpv(xXx,yYy) it's like:
```
sprite.transformAnchor = cpv (xXx,yYy);          // old transformAnchor
sprite.anchorPoint = cpv (xXx/sprSize.width, yYy/sprSize.height);  // new anchorPoint
```
where sprSize is defined as
CGSize sprSize = [sprite contentSize];

It may look like you need more coding for same thing, but then, it was also more coding before if you wanted to have your anchor at the (top,right) of your sprite, for example.
Posted 2 years ago #
Clain
Member

Maybe we could add a convenient method in CocosNode to set the anchor point's position in pixels.

Posted 2 years ago #
coolman
Member

crmagicxxx, Thanks for the point.

Posted 2 years ago #

RSS feed for this topic

Reply

You must log in to post.