if (CGRectIntersectsRect(projectileRect, targetRects))
{
NSLog(#"ha ha Collision detected");
}
CGRect projectileRect = [player boundingBox];
CGRect targetRects = [anEnemy boundingBox];
This is the code i am using for collision.The problem is many time the collision get not checked.If it get checked the position of collision is bottom left or right.
PLease advise what to do or any sample of how to do collision.ALso i am not using box or chimpunk
Make sure to check if the object has passed through the object as well. Ray has some great tuts on all of this here
Related
I've spent too long on this. Someone has solved this already, please help.
Enemy fires on my ship. SKPhysicsContact takes over and I get contactPoint. I explode the fired missile at the contactPoint, in world coordinates. All good. Now I would like to use the point, not in the scene coordinates returned by contactPoint, but in my ship coordinates to start emitting smoke from the ship, where I've been hit. I've used convertPoint function before, with success, but I can't seem to get it right here...Docs say the contactPoint is expressed in Scene coordinates, while myShip has its coordinates, living as a child of a world node, which is a child of the scene node. They are in the same Node hierarchy. I think...I have a Scene->World->Camera, where myShip is a child of World. My code, I think, is saying convert contactPoint from Scene coordinates to coordinates in myShip. But this does not work. Nor does any other combination. What am I missing? I suspect the Camera hierarchy, but unsure. The numbers being returned into smoke.position are way out of whack...
- (SKEmitterNode *) newSmokeEmitter: (SKPhysicsContact *) contact
{
NSString *smokePath = [[NSBundle mainBundle] pathForResource:#"ShipSmoke" ofType:#"sks"];
SKEmitterNode *smoke = [NSKeyedUnarchiver unarchiveObjectWithFile:smokePath];
smoke.targetNode = myShip;
smoke.name = #"shipSmoke";
smoke.position = [self convertPoint:contact.contactPoint toNode:myShip];
//my temporary kludge that places the smoke on the ship, randomly
//smoke.position = CGPointMake(skRand(-25,25), skRand(-25,+25));
NSLog(#"Ship at world pos: %f,%f", myShip.position.x, myShip.position.y);
NSLog(#"Contact at scene pos: %f,%f", contact.contactPoint.x, contact.contactPoint.y);
NSLog(#"Smoke position at ship pos: %f,%f", smoke.position.x, smoke.position.y);
[myShip addChild:smoke];
return smoke;
}
If you haven't solved it already, the answer is to convert from the node's scene:
smoke.position = [self convertPoint:contact.contactPoint fromNode:self.scene];
Or, in Swift:
smoke.position = convertPoint(contact.contactPoint, fromNode: scene)
If I understand your node hierarchy correctly this could fix the issue.
CGPoint contact = [self convertPoint:contact.contactPoint toNode:self.world];
smoke.position = [self.world convertPoint:contact toNode:myShip];
I don't think you can convert the point directly to ship. You have to convert it down the hierarchy until you get to the node you want.
Hopefully that helps.
Edit
To verify that the actual contact point is on the scene where I would expect you could try this.
SKSpriteNode *sprite = [SKSpriteNode spriteNodeWithColor:[SKColor greenColor] size:CGSizeMake(50, 50)];
sprite.position = contact.contactPoint;
[self addChild:sprite];
This should add a sprite exactly where the contact point is if the point returned is in the scene coordinate system. If it it does show up at the right spot than it truly does come down to converting points correctly.
Reanimating a bouncing ball in sprite-kit
I have a question about the best way to reanimate a bouncing ball. Using Ray Wenderlich's tutorial on building a break out game as a reference I have a number of circular shape nodes which continually bounce around a gravity-less environment. When the user touches one of them, it centers on the screen, stops moving, and transforms into something else. When the user touches it again, it is supposed to transform back into the circular shape node and then continue bouncing around the screen.
I have it all working as I like except for reanimating the ball. The manner in which I stop the animation is simply to set the physicsBody to nil. Once I want to reanimate, I call the method that sets up the physicsBody for the node and I apply an impulse to it. But frustratingly, the impulse does not have the effect I think it should. Clearly, my expectations are incorrect.
Here is the code in question:
- (void)applyPhysics
{
// Set physics properties
self.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius:self.frame.size.width/2];
self.physicsBody.friction = 0.0f;
self.physicsBody.restitution = 1.0f;
self.physicsBody.linearDamping = 0.0f;
self.physicsBody.allowsRotation = NO;
self.physicsBody.collisionBitMask = wallCategory;
self.physicsBody.categoryBitMask = bubbleCategory;
}
- (void)morphPicker
{
BOOL check = NO;
if (check) NSLog(#"morphPicker called.");
[self runAction:[SKAction fadeAlphaTo:0.0 duration:.5]];
if (self.flipped) {
if (check) NSLog(#"The information side is showing.");
self.fillColor = bubbleColors[self.index % bubbleColors.count];
self.alpha = .9;
// Resume physics:
[self applyPhysics];
[self.physicsBody applyImpulse:CGVectorMake(10.0f, -10.0f)];
} else {
// stop physics:
self.physicsBody = nil;
if (check) NSLog(#"The statistic side is showing.");
self.fillColor = [SKColor blackColor];
self.alpha = .9;
[self transformToPickerNode];
[self removeAllChildren];
}
self.flipped = !self.flipped;
}
So my questions are these:
How should I be reanimating the ball if applying an impulse to it is not the correct method?
Is there a more elegant way to stop the animation after centering the node than setting the physicsBody to nil? Even to my novice instincts it feels like a brutish method.
After all my trials and searching for an answer to this I firmly believe that there is no elegant way to apply a new impulse to a sprite and expect it to move in the physics world. Thus my answer must be "it cannot be done at this point." However, my solution of removing all the the animated sprites from the scene and recreating them turned out to be the best solution for a completely different reason. The nature of my physics world caused my "floating bubbles" to eventually end up in the corners of the scene where they remained unmoving. Occasionally removing and recreating them had the effect of sending them happily bouncing around the scene again :)
I am having a physicsSprite of kinematics body type and I want to move the body and sprite bit down and back to its position. I tried it like this Inside update method:
for (NSValue *bodyValue in [self getGoalPostBodiesList])
{
b2Body *gPBody = (b2Body *)[bodyValue pointerValue];
PhysicsSprite *pSprite =(PhysicsSprite *) gPBody->GetUserData();
NSLog(#"\n tag value of Sprite = %d",pSprite.tag);
if(pSprite == goal1)
{
pSprite.position = CGPointMake((gPBody->GetPosition().x)*32.0,(gPBody->GetPosition().y)*32.0);
float angle = gPBody->GetAngle();
pSprite.rotation = -(CC_RADIANS_TO_DEGREES(angle));
id moveDownAction = [CCMoveTo actionWithDuration:0.5 position:CGPointMake(pSprite.position.x,(pSprite.position.y )- 40)];
id moveUpAction = [CCMoveTo actionWithDuration:0.5 position:CGPointMake(pSprite.position.x,(pSprite.position.y )+ 40)];
CCSequence *seqAction = [CCSequence actions:moveDownAction,moveUpAction, nil];
[pSprite runAction:seqAction];
b2Vec2 pos = b2Vec2(pSprite.position.x/32.0, pSprite.position.y/32.0);
gPBody->SetTransform(pos, CC_DEGREES_TO_RADIANS(pSprite.rotation));
gPBody->SetLinearVelocity(b2Vec2(0.0f, 0.0f));
gPBody->SetAngularVelocity(0.0f);
}
}
Still the sprite is not changing its position.
Anyone's help will be deeply appreciated.
Thanks all,
MONISH
To summarize your code, you update the position of your sprite to reflect that of the body, start an animation, and then update the position of the body to correspond to the position of the sprite. So naturally, nothing should move here, since your CCMoveTo actions have not exerted any effect on your sprite yet.
Second, your update method may be called very often, like dozens of times per second, so the animation gets reset continously and will not make any visible progress.
To follow a consistent pattern, how about you set the velocity of your kinematic bodies. Also, update the position of your sprites to correspond to these bodies as you would do for dynamic bodies, but don't set the transformation of your bodies to correspond to their sprites.
I have an iOS game, and when a ball hits a target it explodes.
What would be the best way to animate this explosion?
If you're looking for something simple.
Make a series of images that animate the explosion. Add those to a UIImageView and start the animation. Something like this:
UIImage *image0 = [UIImage imageNamed:#"explosion0.png"];
UIImage *image1 = [UIImage imageNamed:#"explosion1.png"];
UIImage *image2 = [UIImage imageNamed:#"explosion2.png"];
UIImage *image3 = [UIImage imageNamed:#"explosion3.png"];
myImageView.animationImages = [NSArray arrayWithObjects:image0, image1, image2, image3, nil];
[myImageView setAnimationDuration:0.75f];
[myImageView startAnimation];
For a bouncing ball game, the Cocos2D game- and Box2d physics- (included with Cocos2D) engines are a great way to go.
Ray Wenderlich has three great tutorials on exactly what you want to do:
Intro to Box2D with Cocos2D Tutorial: Bouncing Balls
How To Create A Breakout Game with Box2D and Cocos2D Tutorial: Part 1
How To Create A Breakout Game with Box2D and Cocos2D Tutorial: Part 2
Once you get past the basics of working with Box2d objects, the key step is to create a Contact Listener (as described in the tutorials) which will tell you when you have a collision. Check (by iterating over contacts in your tick method) if the colliding objects are the ones you want for the explosion, and if so add them to a vector of objects to be destroyed (we can't do this while iterating over contacts or we will invalidate the iterator). Remember the coordinates of the collision and set a flag for explosion.
After exiting the loop destroy the bodies and run the explosion effect at the saved position.
Cocos2D has some very nice built-in explosion effects, and the one I am using for my project is CCParticleSun. You can find some screenshots of someone using this effect here. (The curiously named CCParticleExplosion just gave a lot of confetti flying around the screen.)
Here is the relevant portion from some preliminary code I have working, which is mostly from the tutorial. You will still need to do everything else, eg. create and set up your world and bodies in your init method, update positions, apply forces, and draw in your tick method, implement your Contact Listener class, etc. For all this refer to the tutorials.
std::vector<b2Body *>toDestroy;
std::vector<MyContact>::iterator pos;
CGPoint p;
bool explode = FALSE;
for(pos = _contactListener->_contacts.begin();
pos != _contactListener->_contacts.end(); ++pos) {
MyContact contact = *pos;
if ((contact.fixtureA->GetBody() == _moonBody && contact.fixtureB->GetBody() == _moon2Body) ||
(contact.fixtureA->GetBody() == _moon2Body && contact.fixtureB->GetBody() == _moonBody)) {
NSLog(#"Moons collided!");
explode = TRUE;
p = CGPointMake(PTM_RATIO*(_moonBody->GetPosition().x + _moon2Body->GetPosition().x)/2.,PTM_RATIO*(_moonBody->GetPosition().y + _moon2Body->GetPosition().y)/2.);
if (std::find(toDestroy.begin(), toDestroy.end(), _moonBody) == toDestroy.end()) {
toDestroy.push_back(_moonBody);
}
if (std::find(toDestroy.begin(), toDestroy.end(), _moon2Body) == toDestroy.end()) {
toDestroy.push_back(_moon2Body);
}
}
}
std::vector<b2Body *>::iterator pos2;
for(pos2 = toDestroy.begin(); pos2 != toDestroy.end(); ++pos2) {
b2Body *body = *pos2;
if (body->GetUserData() != NULL) {
CCSprite *sprite = (CCSprite *) body->GetUserData();
[sprite.parent removeChild:sprite cleanup:YES]; }
world->DestroyBody(body);
}
if (explode)
{
explosion = [[CCParticleSun alloc]initWithTotalParticles:250];
explosion.texture = [[CCTextureCache sharedTextureCache] addImage:#"fire.png"];
explosion.autoRemoveOnFinish = YES;
explosion.startSize = 15.0f;
explosion.speed = 30.0f;
explosion.position = p;
explosion.duration = 1.0f;
[self addChild:explosion z:self.zOrder+1];
}
What you want, then, is a way to create a particle emission system. My suggestion is to use a CAEmitterLayer. Ray Wenderlich has a great tutorial: UIKit Particle Systems in iOS 5 Tutorial
iPhone Programming Tutorial: Animating a Game Sprite
If you need to make an explosion another alternative would to use Cocos2d and do:
CCParticleSun *anExplosion=[CCParticleGalaxy node];
[kk setPosition:ball.position];
[self addChild:anExplosion];
Not really an animation, also, from the question you don't seem to be using Cocos2d, but if you start using it you can do this...
hi i have a problem with sprite during startup
The problem is that the sprite rotates 180 degree to and fro once before setting to its position.
It happens very fast.
I know it is some bug but couldnt find the problem.
Can anyone please help me.
The code are as follows
CCSprite *arrowSprite = [[CCSprite spriteWithFile:#"Launcher2.png"] retain];
CGSize size = [arrowSprite contentSize];
arrowSprite.anchorPoint = ccp(25/size.width,20/size.height);
NSLog(#"Value of anchorPoint x,y %f, %f",arrowSprite.anchorPoint.x,arrowSprite.anchorPoint.y);
arrowSprite.position = ccp(65, 80);
[self addChild:arrowSprite z:1];
I don't see anything in your code that would cause any rotation of the sprite. You can confirm this by reducing the posted code down to the bare bones by commenting out the line that sets the anchorPoint. If you're still getting the rotation, it's happening somewhere else in your application.