Touch event on rotating sprite « cocos2d for iPhone

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Touch event on rotating sprite

(6 posts) (2 voices)

Started 1 year ago by calsmith
Latest reply from mobilebros

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calsmith
Member
Hi, I have tried every possible method of sprite touch detection I can find and none of them seem to work with sprites that have rotated

my code:
```
//add circle sprite hit zone (this is what I need touch detection for)
		circleHitZone = [CCSprite spriteWithFile:@"circle_10_hitzone.png"];
		circleHitZone.anchorPoint = ccp(0,-0.9);//this is probs messing it up
		circleHitZone.position = ccp(winSize.width /2 , winSize.height/2);
		circleHitZone.color = ccc3(150,10,5);
		[self addChild:circleHitZone];

		//start rotations
		id rotHit = [CCRotateBy actionWithDuration:20 angle:360];
		id infinRotateHit = [CCRepeatForever actionWithAction: [CCSequence actions: rotHit, nil]];
		[circleHitZone runAction:infinRotateHit];
```
I'm trying to detect when 'circleHitZone' is tapped but all methods either don't work at all or work when I tap the anchor point
I have tried creating a sprite that follows the circleHitZone but it just goes to the anchor point as well :(

If anyone has any ideas please help me out, anything is appreciated
Thanks.

PS. screenshot of app scene (brown segment is circleHitZone) -> http://cl.ly/e770911a8c6c022fb6e5
Posted 1 year ago #
mobilebros
Moderator

I personally am not really understanding what you're asking. Is that just one big image thats rotating and you want to detect if a touch was "inside" the circle or are you trying to detect a touch on one of those "squares"?

Posted 1 year ago #
calsmith
Member

No it's not just one big image, the white "squares" are all one image, but circleHitZone is this image:
circleHitZone = http://cl.ly/7e47f706338c3baea865
circleHitZone rotates around the larger white one, I want touch detection for circleHitZone but since the sprite is rotating and has a different anchor point I haven't been able to get touch events to work.

I hope I've made it more clear.

Posted 1 year ago #
mobilebros
Moderator
ok yes thats a bit clearer now. So yes probably part of it is due to your anchor, I assume just doing a quick radius check against the center pt of your circleHitZone piece is adequate enough for you?

I would say that the "center" pt on that image looks to be 50 pixels right and 40 pixels up, your anchor point is shifting your image up by 90 pixels (.9*100). So the point relative to the node is ccp(50,130). Given that your code should look something like the following for touch detection:
```
const int radius = 20; //maybe more?

CGPoint tpt = [circleHitZone convertTouchToNodeSpace:touch];

if (ccpLengthSQ(ccpSub(tpt, ccp(50,130))) < radius*radius)
{
      //it was hit!
}
```
I think all that works out correctly....
Posted 1 year ago #

calsmith
Member

EDIT: Wow thanks so much that works perfectly! =D
I just had to add another segment to the if statement so that the point for touch detection isn't so precise:

- (void)ccTouchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
	const int radius = 10;

	UITouch *touch = [touches anyObject];
	CGPoint tpt = [circleHitZone convertTouchToNodeSpace:touch];

	if ((ccpLengthSQ(ccpSub(tpt, ccp(53,38))) < radius*radius) || (ccpLengthSQ(ccpSub(tpt, ccp(53,38))) < (radius*radius+999)))
	{
		//it was hit!
		NSLog(@"hit!");
	} else {
		NSLog(@"no hit");
	}
}

Posted 1 year ago #

mobilebros
Moderator

Nice glad to hear it!, I see that the anchor point calculation was left out, so that didn't make any difference?

Also I think you can remove the first part of your "or" statement because it's just redundant now (the second case is always true if the first is true); and actually instead of doing +999 just increase the radius to 33.

Posted 1 year ago #

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