Camera Damping « cocos2d for iPhone

cocos2d for iPhone » Programming » physics

Camera Damping

(7 posts) (3 voices)

Started 1 year ago by inewland53
Latest reply from asinesio

Tags:

Hello -
At the moment I have a camera attached to a physics body. The camera follows accordingly and as needed. However, I would like to expand the camera to apply a 'damping' or spring.

Camera movement directly applies a snap-to-center, but I'd like to integrate the damping to the camera.

Here is what I'm using -

-(void)setViewpointCenter:(CGPoint) position {

    CGSize winSize = [[CCDirector sharedDirector] winSize];

    int x = MAX(position.x, winSize.width / 2);
    int y = MAX(position.y, winSize.height / 2);
    x = MIN(x, (_tileMap.mapSize.width * _tileMap.tileSize.width)
			- winSize.width / 2);
    y = MIN(y, (_tileMap.mapSize.height * _tileMap.tileSize.height)
			- winSize.height/2);
    CGPoint actualPosition = ccp(x, y);

    CGPoint centerOfView = ccp(winSize.width/2, winSize.height/2);
    CGPoint viewPoint = ccpSub(centerOfView, actualPosition);
    self.position = viewPoint;

}

This comes directly from How To Make A Tile Based Game with Cocos2D

Any help on this matter would be greatly appreciated.
Thanks in advance.

Posted 1 year ago #

jordo
Member

keep track of the delta differece in position, and adjust with a mult factor...

-(void)setViewpointCenter:(CGPoint) position {

    CGSize winSize = [[CCDirector sharedDirector] winSize];

    int x = MAX(position.x, winSize.width / 2);
    int y = MAX(position.y, winSize.height / 2);
    x = MIN(x, (_tileMap.mapSize.width * _tileMap.tileSize.width)
			- winSize.width / 2);
    y = MIN(y, (_tileMap.mapSize.height * _tileMap.tileSize.height)
			- winSize.height/2);
    CGPoint actualPosition = ccp(x, y);

    CGPoint centerOfView = ccp(winSize.width/2, winSize.height/2);
    CGPoint viewPoint = ccpSub(centerOfView, actualPosition);

//view point is where you want to go...
    self.position = self.position + (viewPoint - self.position)/2.0;

}

there's no x and y coordinates here, but hopefully it gets the point accross...

the adjust factor in this case would be 2.0 the delta difference between frames...

Posted 1 year ago #

jordo
Member

so... each time you call 'setViewpointCenter', it would get closer and close to the actual viewpoint by halfing the distance every call...

Posted 1 year ago #
inewland53
Member
Hey Jordo - Thanks for the quick reply!

Well I have attempted to implement the idea that you gave me with little success. I might need a bit more help with my math.

So far I have:
```
self.position = ccpMult(ccpAdd(self.position,ccpSub(viewPoint, self.position)), 0.5);
```
This almost works...but I can't seem to find a function to divide. But we are headed in the right direction I believe.

Any more help would be great.
Posted 1 year ago #
jordo
Member
yep... you just actually only want to multiply the DELTA by a half....
```
self.position = ccpAdd(self.position,ccpMult(ccpSub(viewPoint, self.position), 0.5));
```
Posted 1 year ago #

inewland53
Member

@jordo

Hey thanks a bunch, that did the trick! Here's the final code:

-(void)setViewpointCenter:(CGPoint) position {

    CGSize winSize = [[CCDirector sharedDirector] winSize];

    int x = MAX(position.x, winSize.width / 2);
    int y = MAX(position.y, winSize.height / 2);
    x = MIN(x, (_tileMap.mapSize.width * _tileMap.tileSize.width)
			- winSize.width / 2);
    y = MIN(y, (_tileMap.mapSize.height * _tileMap.tileSize.height)
			- winSize.height/2);
    CGPoint actualPosition = ccp(x, y);

    CGPoint centerOfView = ccp(winSize.width/2, winSize.height/2);
    CGPoint viewPoint = ccpSub(centerOfView, actualPosition);

   //self.position = viewPoint;

	// Camera damping...
	float damping = 0.1f;

	self.position = ccpAdd(self.position,ccpMult(ccpSub(viewPoint, self.position), damping));
}

Posted 1 year ago #

asinesio
Member
I just used this same code to great effect. Thank you for your help, everyone.

Also, if you are integrating with Chipmunk SpaceManager, it helps to override the "setPosition" method on whatever node you want to center the camera on to call this "setViewpointCenter" method (which I have on a singleton GameController).

It seems to be much smoother than when I had it calling from the layer's update: method, but YMMV.

For example:

Ship.h
```
#import <Foundation/Foundation.h>
#import "cpCCSprite.h"
#import "GameController.h"

@interface Ship : cpCCSprite<cpCCNodeProtocol> {

}

-(void) setPosition: (CGPoint)newPosition;

@end
```
Ship.m
```
#import "Ship.h"
@implementation Ship

// Override setPosition so that we tell the screen to move.
-(void) setPosition: (CGPoint)newPosition {
  [super setPosition:newPosition];
  [[GameController sharedInstance] setViewpointCenter:newPosition];
}

@end
```
Posted 1 year ago #

RSS feed for this topic

Reply

You must log in to post.