Pro OpenGL ES for iOS

250 CHAPTER 8: Putting It All Together^

gestures are also handled. However, they did leave out momentum swipes, the kind of

action that can keep a list scrolling for a while after you’ve lifted your finger.

Here we’ll need only the pinch and pan gestures. To your view controller’s

viewDidLoad() method, add Listing 8-2.

Listing 8-2. Allocating the gesture recognizers

UIPinchGestureRecognizer *pinchGesture =

[[UIPinchGestureRecognizer alloc]initWithTarget:self

action:@selector(handlePinchGesture:)];

[self.view addGestureRecognizer:pinchGesture];

UIPanGestureRecognizer *panGesture =

[[UIPanGestureRecognizer alloc]initWithTarget:self

action:@selector(handlePanGesture:)];

[self.view addGestureRecognizer:panGesture];

Next we need to add the two handlers, handlePanGesture() and handlePinchGesture(),

shown in Listing 8-3.

Listing 8-3. The Two Handlers for the Gesture Recognizers

• (IBAction)handlePanGesture:(UIPanGestureRecognizer *)sender
  {
  static CGPoint prevLocation;
  CGPoint translate = [sender translationInView:self.view];

UIGestureRecognizerState state;

state=sender.state;

if(state==UIGestureRecognizerStateBegan)

{

prevLocation=translate;

[m_SolarSystem lookAtTarget];

}

else if(state==UIGestureRecognizerStateChanged)

{

CGPoint currlocation =translate;

m_PointerLocation=CGPointMake(currlocation.x, currlocation.y);

[self setHoverPosition:0 location:currlocation prevLocation:prevLocation];

prevLocation=currlocation;

}

}