Chipmunk Physics

Code: Select all

static void
click(int button, int state, int x, int y)
{
	if(button == GLUT_LEFT_BUTTON){
		if(state == GLUT_DOWN){
			cpVect point = mouseToSpace(x, y);
		
			cpShape *shape = cpSpacePointQueryFirst(space, point, GRABABLE_MASK_BIT, 0);
			if(shape){
				cpBody *body = shape->body;
				mouseJoint = cpPivotJointNew2(mouseBody, body, cpvzero, cpBodyWorld2Local(body, point));
				mouseJoint->maxForce = 50000.0f;
				mouseJoint->biasCoef = 0.15f;
				cpSpaceAddConstraint(space, mouseJoint);
			}
		} else if(mouseJoint){
			cpSpaceRemoveConstraint(space, mouseJoint);
			cpConstraintFree(mouseJoint);
			mouseJoint = NULL;
		}
	}
}

Code: Select all

	cpVect newPoint = cpvlerp(mousePoint_last, mousePoint, 0.25f);
	mouseBody->p = newPoint;
	mouseBody->v = cpvmult(cpvsub(newPoint, mousePoint_last), 60.0f);
	mousePoint_last = newPoint;

Code: Select all

-(id) init {
	if( (self=[super init])) {
		
		self.isTouchEnabled = YES;
		
		CGSize wins = [[CCDirector sharedDirector] winSize];
		cpInitChipmunk();
		
		mouseBody = cpBodyNew(INFINITY, INFINITY);
		
		cpBody *staticBody = cpBodyNew(INFINITY, INFINITY);
		space = cpSpaceNew();
		cpSpaceResizeStaticHash(space, 400.0f, 40);
		cpSpaceResizeActiveHash(space, 100, 600);
		
		space->gravity = ccp(0, 0);
		space->elasticIterations = space->iterations;

		[self schedule: @selector(step:)];
}

-(void) step {

	int steps = 1;
	cpFloat dt = 1.0f/60.0f/(cpFloat)steps;

	for(int i=0; i<steps; i++){
		// turn the control body based on the angle relative to the actual body
		cpVect mouseDelta = cpvsub(mousePoint, spaceBody->p);
		
		cpFloat turn = cpvtoangle(cpvunrotate(spaceBody->rot, mouseDelta));
		
		cpBodySetAngle(spaceControlBody, spaceBody->a - turn);
		
		// drive the tank towards the mouse
		if(cpvnear(mousePoint, spaceBody->p, 30.0)){
			spaceControlBody->v = cpvzero; // stop
		} else {
			cpFloat direction = (cpvdot(mouseDelta, spaceBody->rot) > 0.0 ? 1.0 : -1.0);
			spaceControlBody->v = cpvrotate(spaceBody->rot, cpv(30.0f*direction, 0.0f));
		}
		cpSpaceStep(space, dt);
	}

}

-(void) makeSpaceShips {
	
	CGSize winSize = [[CCDirector sharedDirector] winSize];

	CCTexture2D * texture = [[CCTextureCache sharedTextureCache] addImage:@"space.png"];
	spaceOne = [[CCSprite alloc] initWithTexture:texture];
	spaceOne.rotation = -90.f;
	spaceOne.position = CGPointMake(winSize.width/2 - (spaceOne.contentSize.width/2) + 20, 100);
	[self addChild:spaceOne z:10];

	// 86 x 47
	cpVect oneVerts[] = {
	cpv(43, 23.5),
	cpv(43, -23.5),
	cpv(-43, -23.5), 
	cpv(-43, 23.5), 
	};
	
	spaceBody = cpBodyNew(100.0, INFINITY);
	spaceBody->p = cpv(winSize.width/2 - (spaceOne.contentSize.width/2) + 20, 100);
	cpSpaceAddBody(space, spaceBody);
	
	cpShape * spaceOneShape = cpPolyShapeNew(spaceBody, 4, oneVerts, cpvzero);
	spaceOneShape->data = spaceOne;
	spaceOneShape->e = 0.0;
	spaceOneShape->u = 0.0;
	spaceOneShape->collision_type = 1;
	cpSpaceAddShape(space, spaceOneShape);
	
	spaceControlBody = cpBodyNew(INFINITY, INFINITY);
	
	cpConstraint * pivot = cpSpaceAddConstraint(space, cpPivotJointNew2(spaceControlBody, spaceBody, cpvzero, cpvzero));
	pivot->biasCoef = 0.0f; // disable joint correction
	pivot->maxForce = 10000.0f; // emulate linear friction

	cpConstraint * gear = cpSpaceAddConstraint(space, cpGearJointNew(spaceControlBody, spaceBody, 0.0f, 1.0f));
	gear->biasCoef = 1.0f; // limit angular correlation rate
	gear->maxBias = 1.0f; // limit angular correction rate
	gear->maxForce = 500000.f; // emulate angular friction
	
}

-(void) ccTouchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
	
	UITouch *myTouch = [touches anyObject];
	
	CGPoint location = [myTouch locationInView: [myTouch view]];
	location = [[CCDirector sharedDirector] convertToGL: location];
	
	cpVect point =  [self convertTouchToNodeSpace:myTouch]; //cpv(location.x, location.y);
	mousePoint = point;
	
	cpShape *shape = cpSpacePointQueryFirst(space, location, GRABABLE_MASK_BIT, 0);
	if ( shape ) {
		cpBody *body = shape->body;
		
		mousePoint_last = mousePoint;
		mouseBody->p = mousePoint;
		
		mouseJoint = cpPivotJointNew2(mouseBody, body, cpvzero, cpBodyWorld2Local(body, location));
		mouseJoint->maxForce = 50000.0f;
		mouseJoint->biasCoef = 0.15f;
		cpSpaceAddConstraint(space, mouseJoint);
	}
	
}

-(void) ccTouchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
	
	UITouch *myTouch = [touches anyObject];
	
	CGPoint location = [myTouch locationInView: [myTouch view]];
	location = [[CCDirector sharedDirector] convertToGL: location];
	
	cpVect point = [self convertTouchToNodeSpace:myTouch]; // cpv(location.x, location.y);
	mousePoint = point;
	
}

-(void)ccTouchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {

	if (cpArrayContains(space->constraints, mouseJoint)) {
		cpSpaceRemoveConstraint(space, mouseJoint);
		cpConstraintFree(mouseJoint);
		mouseJoint = nil;
	}
	
}

Code: Select all

cpVect mousePosLast;
cpBody *dragBody = 0;

void clickFunc(int button, int state, int x, int y)
{
	if( button == GLUT_LEFT_BUTTON )
	{
		if( state == GLUT_DOWN )
		{
			mousePosLast = mouseToSpace(x, y);

			cpShape *shape = cpSpacePointQueryFirst(space, mousePosLast, CP_ALL_LAYERS, CP_NO_GROUP);

			dragBody = (shape) ? shape->body : 0;
		}
		else
			dragBody = 0;
	}
}

void dragFunc(int x, int y)
{
	if( dragBody )
	{
		cpVect mousePos = mouseToSpace(x, y);

		// Update body's position
		dragBody->p = cpvadd(dragBody->p, cpvsub(mousePos, mousePosLast));
		// Stop body. Isn't necessary
		dragBody->v = cpvzero;
		
		// Walk throught body's shapes and update space hash for them
		cpShape *shapes = dragBody->shapesList;

		while( shapes )
		{
			cpSpaceRehashShape(space, shapes);
			shapes = shapes->next;
		}

		mousePosLast = mousePos;

		glutPostRedisplay();
	}
}