Rotate a sprite in cocos2d using accelerometer - iphone

Question

I'm on cocos2d and I have a sprite that I would like to rotate with the accelerometer.
I've heard about CMMotionManager. I would like to know if it is possible to use it just for 2D rotation, and, if yes, how?

Answer 1

put this in onEnter:
UIAccelerometer *accelerometer = [UIAccelerometer sharedAccelerometer];
accelerometer.updateInterval = 1.0/50.0; //update interval in sec...so 1/50= 20 ms
accelerometer.delegate = self;
you need to conform to UIAccelerometerDelegate like so:
#interface MyClass:CCLayer <UIAccelerometerDelegate>
and implement this in MyClass.m:
- (void)accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration {
CCLOG(#"x = %f y = %f z = %f",acceleration.x,acceleration.y,acceleration.z);
mysprite.rotation=acceleration.x*20;
}
edit: almost forgot...put accelerometer.delegate = nil; in onExit
note that the method is called every time the accelerometer changes value..in all 3 vectors
cards on the table..i didnt use accelerometer ...ever..but it should look something like this...check the rotation property in the documentation and play a little with it
hope it helps
PS: loved the "sorry for my english i'm french" part...hilarious
edit: here is my test of that code..and made a few modifications..it works fairly smooth..if you dont like it play around with the values.
#import "cocos2d.h"
// HelloWorldLayer
UIAccelerationValue accelerationX;
UIAccelerationValue accelerationY;
float currentRawReading;
float calibrationOffset;
#interface HelloWorldLayer : CCLayer <UIAccelerometerDelegate>
{
CCLabelTTF *label;
}
// returns a CCScene that contains the HelloWorldLayer as the only child
+(CCScene *) scene;
#end
#import "HelloWorldLayer.h"
// HelloWorldLayer implementation
#implementation HelloWorldLayer
+(CCScene *) scene
{
// 'scene' is an autorelease object.
CCScene *scene = [CCScene node];
// 'layer' is an autorelease object.
HelloWorldLayer *layer = [HelloWorldLayer node];
// add layer as a child to scene
[scene addChild: layer];
// return the scene
return scene;
}
#define kFilteringFactor .05
CGFloat RadiansToDegrees(CGFloat radians) {return radians *180/M_PI;};
// on "init" you need to initialize your instance
-(id) init
{
// always call "super" init
// Apple recommends to re-assign "self" with the "super" return value
if( (self=[super init])) {
UIAccelerometer *accel= [UIAccelerometer sharedAccelerometer];
accel.delegate=self;
accel.updateInterval=1/60;
// create and initialize a Label
label = [CCLabelTTF labelWithString:#"Hello World" fontName:#"Marker Felt" fontSize:64];
// ask director the the window size
CGSize size = [[CCDirector sharedDirector] winSize];
// position the label on the center of the screen
label.position = ccp( size.width /2 , size.height/2 );
label.flipY=YES; //i have absolutly no idea why the label is fliped :/
label.flipX=YES;
label.rotation=0;
// add the label as a child to this Layer
[self addChild: label];
}
return self;
}
-(void)accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration{
CCLOG(#"acc called");
accelerationX=acceleration.x *kFilteringFactor +accelerationX *(1-kFilteringFactor);
accelerationY=acceleration.y*kFilteringFactor +accelerationY *(1-kFilteringFactor);
currentRawReading=atan2(accelerationY, accelerationX);
label.rotation=-RadiansToDegrees(currentRawReading);
}
// on "dealloc" you need to release all your retained objects
- (void) dealloc
{
// in case you have something to dealloc, do it in this method
// in this particular example nothing needs to be released.
// cocos2d will automatically release all the children (Label)
// don't forget to call "super dealloc"
[super dealloc];
}
#end