BoxTestViewController.mm

#import "BoxTestViewController.h"


#import <Box2D/Box2D.h>


#define PTM_RATIO 16


@interface BoxTestViewController ()
@property (assign) b2World *world;
@property (retain) CADisplayLink *displayLink;
@end


@implementation BoxTestViewController

@synthesize world, displayLink;

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    return YES;
}

- (void)dealloc {
    [super dealloc];
}

-(void)createPhysicsWorld
{
	CGSize screenSize = self.view.bounds.size;
	
	NSLog(@"screenSize: %@", NSStringFromCGSize(screenSize));
	
	// Define the gravity vector.
	b2Vec2 gravity;
	gravity.Set(0.0f, -9.81f);
	
	// Do we want to let bodies sleep?
	// This will speed up the physics simulation
	bool doSleep = true;
	
	// Construct a world object, which will hold and simulate the rigid bodies.
	world = new b2World(gravity, doSleep);
	
	world->SetContinuousPhysics(true);
	
	// Define the ground body.
	b2BodyDef groundBodyDef;
	groundBodyDef.position.Set(0, 0); // bottom-left corner
	
	// Call the body factory which allocates memory for the ground body
	// from a pool and creates the ground box shape (also from a pool).
	// The body is also added to the world.
	b2Body* groundBody = world->CreateBody(&groundBodyDef);
	
	// Define the ground box shape.
//	b2PolygonShape groundBox;
	
//	// bottom
//	groundBox.SetAsEdge(b2Vec2(0,0), b2Vec2(screenSize.width/PTM_RATIO,0));
//	groundBody->CreateFixture(&amp;groundBox, 0);
//	
//	// top
//	groundBox.SetAsEdge(b2Vec2(0,screenSize.height/PTM_RATIO), b2Vec2(screenSize.width/PTM_RATIO,screenSize.height/PTM_RATIO));
//	groundBody->CreateFixture(&amp;groundBox, 0);
//	
//	// left
//	groundBox.SetAsEdge(b2Vec2(0,screenSize.height/PTM_RATIO), b2Vec2(0,0));
//	groundBody->CreateFixture(&amp;groundBox, 0);
//	
//	// right
//	groundBox.SetAsEdge(b2Vec2(screenSize.width/PTM_RATIO,screenSize.height/PTM_RATIO), b2Vec2(screenSize.width/PTM_RATIO,0));
//	groundBody->CreateFixture(&amp;groundBox, 0);



	b2EdgeShape groundBox;
	
	// bottom
	groundBox.Set(b2Vec2(0,0), b2Vec2(screenSize.width/PTM_RATIO,0));
	groundBody->CreateFixture(&groundBox, 0);
	
	// top
	groundBox.Set(b2Vec2(0,screenSize.height/PTM_RATIO), b2Vec2(screenSize.width/PTM_RATIO,screenSize.height/PTM_RATIO));
	groundBody->CreateFixture(&groundBox, 0);
	
	// left
	groundBox.Set(b2Vec2(0,screenSize.height/PTM_RATIO), b2Vec2(0,0));
	groundBody->CreateFixture(&groundBox, 0);
	
	// right
	groundBox.Set(b2Vec2(screenSize.width/PTM_RATIO,screenSize.height/PTM_RATIO), b2Vec2(screenSize.width/PTM_RATIO,0));
	groundBody->CreateFixture(&groundBox, 0);



}


-(void)addPhysicalBodyForView:(UIView *)physicalView
{
	// Define the dynamic body.
	b2BodyDef bodyDef;
	bodyDef.type = b2_dynamicBody;
	
	CGPoint p = physicalView.center;
	CGPoint boxDimensions = CGPointMake(physicalView.bounds.size.width/PTM_RATIO/2.0,physicalView.bounds.size.height/PTM_RATIO/2.0);
	
	bodyDef.position.Set(p.x/PTM_RATIO, (self.view.bounds.size.height - p.y)/PTM_RATIO);
	bodyDef.userData = physicalView;
	
	// Tell the physics world to create the body
	b2Body *body = world->CreateBody(&bodyDef);
	
	// Define another box shape for our dynamic body.
	b2PolygonShape dynamicBox;
	
	dynamicBox.SetAsBox(boxDimensions.x, boxDimensions.y);
	
	// Define the dynamic body fixture.
	b2FixtureDef fixtureDef;
	fixtureDef.shape = &dynamicBox;
	fixtureDef.density = 3.0f;
	fixtureDef.friction = 0.3f;
	fixtureDef.restitution = 0.5f; // 0 is a lead ball, 1 is a super bouncy ball
	body->CreateFixture(&fixtureDef);
	
	// a dynamic body reacts to forces right away
	body->SetType(b2_dynamicBody);
	
	// we abuse the tag property as pointer to the physical body
	physicalView.tag = (int)body;
}

- (void)viewDidLoad
{
	[super viewDidLoad];
}

- (void) didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation;
{
	NSLog(@"blarg");
	[self createPhysicsWorld];
	
	
	for (UIView *oneView in self.view.subviews)
	{
		[self addPhysicalBodyForView:oneView];
	}
	
	//	tickTimer = [NSTimer scheduledTimerWithTimeInterval:1.0/60.0 target:self selector:@selector(tick:) userInfo:nil repeats:YES];
	[self.displayLink invalidate];
	self.displayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(tick:)];
	[self.displayLink addToRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode];
}

//- (void)viewWillAppear:(BOOL)animated;	
//{
//}

-(void) tick:(CADisplayLink *)displayLink
{
	//It is recommended that a fixed time step is used with Box2D for stability
	//of the simulation, however, we are using a variable time step here.
	//You need to make an informed choice, the following URL is useful
	//http://gafferongames.com/game-physics/fix-your-timestep/
	
	int32 velocityIterations = 8;
	int32 positionIterations = 1;
	
	// Instruct the world to perform a single step of simulation. It is
	// generally best to keep the time step and iterations fixed.
	world->Step(1.0f/60.0f, velocityIterations, positionIterations);
	
	//Iterate over the bodies in the physics world
	for (b2Body* b = world->GetBodyList(); b; b = b->GetNext())
	{
		if (b->GetUserData() != NULL)
		{
			UIView *oneView = (UIView *)b->GetUserData();
			
			// y Position subtracted because of flipped coordinate system
			CGPoint newCenter = CGPointMake(b->GetPosition().x * PTM_RATIO,
											self.view.bounds.size.height - b->GetPosition().y * PTM_RATIO);
			oneView.center = newCenter;
			
			CGAffineTransform transform = CGAffineTransformMakeRotation(- b->GetAngle());
			
			oneView.transform = transform;
		}
	}
}
@end