/*

     File: APLInstantaneousPushViewController.m

 Abstract: Provides the "Instantaneous Push + Collision" demo.

 Tapping the view changes the angle and magnitude of the impulse. 

 To visually show the impulse vector on screen, a red arrow representing 

 the angle and magnitude of this vector is briefly drawn on screen.

  Version: 1.3

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 MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION

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 OPERATION ALONE OR IN COMBINATION WITH YOUR PRODUCTS.

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 */

#import "APLInstantaneousPushViewController.h"

#import "APLDecorationView.h"

@interface APLInstantaneousPushViewController ()

@property (nonatomic, weak) IBOutlet UIView *square1;

@property (nonatomic, strong) UIDynamicAnimator *animator;

@property (nonatomic, strong) UIPushBehavior *pushBehavior;

@end

@implementation APLInstantaneousPushViewController

//| ----------------------------------------------------------------------------

- (void)viewDidAppear:(BOOL)animated

{

    [super viewDidAppear:animated];

    UIDynamicAnimator *animator = [[UIDynamicAnimator alloc] initWithReferenceView:self.view];

    UICollisionBehavior *collisionBehavior = [[UICollisionBehavior alloc] initWithItems:@[self.square1]];

    // Account for any top and bottom bars when setting up the reference bounds.

    [collisionBehavior setTranslatesReferenceBoundsIntoBoundaryWithInsets:UIEdgeInsetsMake(self.topLayoutGuide.length, 0, self.bottomLayoutGuide.length, 0)];

    [animator addBehavior:collisionBehavior];

    UIPushBehavior *pushBehavior = [[UIPushBehavior alloc] initWithItems:@[self.square1] mode:UIPushBehaviorModeInstantaneous];

    pushBehavior.angle = 0.0;

    pushBehavior.magnitude = 0.0;

    [animator addBehavior:pushBehavior];

    self.pushBehavior = pushBehavior;

    self.animator = animator;

}

//| ----------------------------------------------------------------------------

//  IBAction for the Tap Gesture Recognizer that has been configured to track

//  touches in self.view.

//

- (IBAction)handlePushGesture:(UITapGestureRecognizer*)gesture

{

    // Tapping will change the angle and magnitude of the impulse. To visually

    // show the impulse vector on screen, a red arrow representing the angle

    // and magnitude of this vector is briefly drawn.

    CGPoint p = [gesture locationInView:self.view];

    CGPoint o = CGPointMake(CGRectGetMidX(self.view.bounds), CGRectGetMidY(self.view.bounds));

    CGFloat distance = sqrtf(powf(p.x-o.x, 2.0)+powf(p.y-o.y, 2.0));

    CGFloat angle = atan2(p.y-o.y, p.x-o.x);

    distance = MIN(distance, 100.0);

    // Display an arrow showing the direction and magnitude of the applied

    // impulse.

    [(APLDecorationView*)self.view drawMagnitudeVectorWithLength:distance angle:angle color:[UIColor redColor] forLimitedTime:YES];

    // These two lines change the actual force vector.

    [self.pushBehavior setMagnitude:distance / 100.0];

    [self.pushBehavior setAngle:angle];

    // A push behavior in instantaneous (impulse) mode automatically

    // deactivate itself after applying the impulse. We thus need to reactivate

    // it when changing the impulse vector.

    [self.pushBehavior setActive:TRUE];

}

@end