I wanted to mix 2 tutorials, namely:
http://hub.ae/blog/2014/03/26/soft-body-physics-jellyusing-spritekit/
and
https://developer.apple.com/library/ios/documentation/GraphicsAnimation/Conceptual/SpriteKit_PG/Actions/Actions.html
(Example: Centering the Scene on a Node part)
I got both working one by one, but I've a bug when I mix both.
If my code starts like this:
[self setAnchorPoint:CGPointMake(0.5f, 0.5f)];
_myWorld = [SKNode node];
[self addChild:_myWorld];
[self createPlayer]; // I replaced all [self addchild's to [_myWorld addChild]
then camera follows the player but there are no joints created!
If I put [self createPlayer] to the top and leave all [self addchilds] as they are (because _myWorld isn't created yet) then there are joints which are working perfectly but camera doesn't follow player, since player isn't in _myWorld.
I leave [self.physicsWorld addJoint:joint]; as it is all the time.
Any idea where I go wrong?
When I moved the parts into _myWorld as told in the Apple guide, I didn't know I also had to shift anchor points, as they are always in scene coordinates.
Adding these lines solved the problem:
CGPoint p1 = [self.scene convertPoint:CGPointMake(point1.position.x+self.frame.size.width/2, point1.position.y+self.frame.size.height/2) fromNode:_myWorld];
CGPoint p2 = [self.scene convertPoint:CGPointMake(point2.position.x+self.frame.size.width/2, point2.position.y+self.frame.size.height/2) fromNode:_myWorld];
in the AttachPoint function.
Related
I have some sprites coming from the bottom of the screen in a random order. I want to swipe the sprite in the direction of the swipe. I got the algorithm for swiping. Also, I get an NSLog message whenever any sprite has been touched in the screen. The NSLog gives correct responses to any and every object touched. But how do I know which sprite has been swiped to write the code for applying impulse to that particular sprite?
I am trying the following code:
SKNode *sprite = [self nodeAtPoint:location];
[ball.physicsBody applyImpulse:CGVectorMake(dx, dy) atPoint:location];
[self addChild:sprite];
Also,
userInteractionEnabled = YES for all the sprites
And all the sprites are performing an action (Just in case this is the reason why I cannot swipe them while they are already running an action, in this case what else should I use to move the sprites?)
Sorry if this is too dumb, I am a noob
Thanks in advance!
You will need to use the name of the sprite with the name property:
node.name = #"nodeName";
for(SKNode *node in [self nodesAtPoint:location])
{
if([node.name isEqualToString:#"nodeName"])
{
// your custom code here
}
}
I hope this is what you were looking for, if not i am always here to help.
So, in this game I'm making the player can move left and right using the accelerometer and jump by tapping the screen. Now the player must evade enemies frome the sky and climb up by jumping on de fallen enemies. The player should be able to go up infinitely until he dies, therefore a camera is needed to follow the player on his journey up. I have read some other Stack Overflow posts and consulted Apple's programming guide, but I'm not able to figure it out. This is what I added:
-(void) createSceneContents
{
self.world = [SKNode node];
self.playerSize = self.frame.size.width/7;
self.player = [self.playerData newPlayer:self.playerSize];
self.player.name = #"player";
self.player.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:CGSizeMake(self.playerSize-5,self.playerSize-5)];
self.player.physicsBody.allowsRotation = NO;
self.player.physicsBody.categoryBitMask = self.playerCategory;
self.player.physicsBody.contactTestBitMask = self.enemyCategory | self.edgeCategory;
self.isTouchingGround = NO;
self.player.position = CGPointMake(CGRectGetMidX(self.frame), 100);
[self.playerData movementSetup];
[self addChild:self.world];
[self.world addChild:self.player];
}
There are more things in this method, but those aren't important for this question.
-(void) didSimulatePhysics
{
self.world.position = CGPointMake(-(self.player.position.x-(self.size.width/2)), -(self.player.position.y-(self.size.height/2)));
}
Then there are a lot of other methods adding other things to the game including enemies, collision handeling etc.
Ok, so when I did this the player movement suddenly stopped working, the players spawn position was changed and the rest of the sprites, that weren't child nodes of world, just kept on going.
Why isn't this working, how can I fix it, and how does it work?
In order to make a camera follow your player add these simple lines of code:
int cameraEdge = 100;
if (self.player.position.y > cameraEdge) {
worldPosition.y = cameraEdge - self.player.position.y;
}
self.world.position = worldPosition;
What this does: Whenever your player's y-position is higher than 100 (or whatever you set it to) the world's position starts following the player. I've tested it and it works perfectly
Two likely related things here:
1) I can draw a box and add to child from my SKScene impelmentation file with self, self.scene, and myWorld, but not with an SKSprite node's scene property.
SKSpriteNode *bla = [SKSpriteNode spriteNodeWithColor:[UIColor redColor] size:CGSizeMake(100, 100)];
[self.scene addChild:bla]; // If I use bla.scene, it doesn't work. self, self.scene, myworld all do work though.
bla.position = CGPointMake(0, 0);
bla.zPosition = 999;
2) I've seen the related questions here and here, but I'm trying to add a joint during gameplay (grabbing a rope). This method gets called after doing some sorting in `didBeginContact:
-(void)monkey:(SKPhysicsBody *)monkeyPhysicsBody didCollideWithRope:(SKPhysicsBody *)ropePhysicsBody atPoint:(CGPoint)contactPoint
{
if (monkeyPhysicsBody.joints.count == 0) {
// Create a new joint between the player and the rope segment
CGPoint convertedRopePosition = [self.scene convertPoint:ropePhysicsBody.node.position fromNode:ropePhysicsBody.node.parent];
SKPhysicsJointPin *jointPin = [SKPhysicsJointPin jointWithBodyA:playerPhysicsBody bodyB:ropePhysicsBody anchor:convertedRopePosition];
jointPin.upperAngleLimit = M_PI/4;
jointPin.shouldEnableLimits = YES;
[self.scene.physicsWorld addJoint:jointPin];
}
}
I've got showPhyiscs enabled on the scene, so I can see that the joint is ending up in a totally wacky place. Unfortunately, I don't know how to apply the linked solutions since I'm not adding the SKSpriteNodes in this method, they already exist, so I can't just flip the order of position and physicsBody.
I've tried every permutation I could for both of the convertPoint methods. Nothing worked. My best guess is that physicsWorld is using some wacky coordinate system.
Method members of SKPhysicsWorld that relate to position (CGPoint) or frame (CGRect) are to be in scene coordinates. Scene coordinates reference the point {0,0} as the bottom left corner and is consistent throughout SpriteKit.
The scene property of your object named bla will be nil when bla is first created and is set by the scene when added to it.
[bla.scene addChild:bla]; // this won't do anything as scene will be nil when first created
It looks as though convertedRopePosition is being assigned an incorrect value because the second member you're passing into, - (CGPoint)convertPoint:(CGPoint)point fromNode:(SKNode *)node , is the scene when it should be another node in the same node tree as this node. where this node is the caller (in this case the SKScene subclass).
Try replacing the line-
CGPoint convertedRopePosition = [self.scene convertPoint:ropePhysicsBody.node.position fromNode:ropePhysicsBody.node.parent];
with-
CGPoint convertedRopePosition = [self convertPoint:ropePhysicsBody.node.position fromNode:ropePhysicsBody.node];
I came up with a janky work around for this problem. It turns out that the coordinate system offset for physicsWorld was likely due to an anchor difference. Changing the anchors of every related thing made no difference, and you can't change the anchor of the physicsWorld directly, so I ended up adding half of the scene width and half of the scene height to the anchor position of my joint. That got it to show in the right place and behave normally.
This problem persisted once side scrolling was factored in. I've posted other questions here with this same problem but I'll include th
I added the following convenience method to my GameScene.m. It essentially takes the place of the seemingly useless convertTo built in method.
-(CGPoint)convertSceneToFrameCoordinates:(CGPoint)scenePoint
{
CGFloat xDiff = myWorld.position.x - self.position.x;
CGFloat yDiff = myWorld.position.y - self.position.y;
return CGPointMake(scenePoint.x + self.frame.size.width/2 + xDiff, scenePoint.y + self.frame.size.height/2 + yDiff);
}
I use this method to add joints. It handles all of the coordinate system transformations that need to be dealt with that lead to the issue raised in this question. For example, the way I add joints
CGPoint convertedRopePosition = [self convertSceneToFrameCoordinates:ropePhysicsBody.node.position];
SKPhysicsJointPin *jointPin = [SKPhysicsJointPin jointWithBodyA:monkeyPhysicsBody bodyB:ropePhysicsBody anchor:convertedRopePosition];
jointPin.upperAngleLimit = M_PI/4;
jointPin.shouldEnableLimits = YES;
[self.scene.physicsWorld addJoint:jointPin];
I am creating a simple Sprite Kit game however when i am adding the PhysicsBody to one of my sprites it seems to be going in the wrong position. i know that it is in the wrong position as i have have set
skView.showsPhysics = YES;
and it is showing up in the wrong position.
The Square in the bottom corner is the physics body for the first semicircle. I am using a square at the moment just for testing purposes.
My app includes view following and follows my main sprite when it moves. I implemented this by following apples documentation and creating a 'myworld' node and creating all other nodes from that node.
myWorld = [SKNode node];
[self addChild:myWorld];
semicircle = [SKSpriteNode spriteNodeWithImageNamed:#"SEMICRICLE.png"];
semicircle.size = CGSizeMake(semicircle.frame.size.width/10, semicircle.frame.size.height/10);
semicircle.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:semicircle.frame.size];
semicircle.position = CGPointMake(self.frame.size.width/2, self.frame.size.height/2);
semicircle.physicsBody.dynamic = YES;
semicircle.physicsBody.collisionBitMask = 0;
semicircle.name = #"semicircle";
[myWorld addChild:semicircle];
To centre on the node I call these methods
- (void)didSimulatePhysics
{
[self centerOnNode: [self childNodeWithName: #"//mainball"]];
}
- (void) centerOnNode: (SKNode *) node
{
CGPoint cameraPositionInScene = [node.scene convertPoint:node.position fromNode:node.parent];
node.parent.position = CGPointMake(node.parent.position.x - cameraPositionInScene.x, node.parent.position.y - cameraPositionInScene.y);
}
I don't know if the my world thing makes any difference to the SkPhysics body...
SKPhysicsBody starts at coordinates 0,0 which is at the bottom left hand corner. If you make the area smaller, as you did by width/10 and height/10, you decrease the size but from the bottom left.
I think what you are looking for is bodyWithRectangleOfSize:center: which allows you to manually set the center from which you base your physics body area on.
Update:
Based on what I understand, your smallest semi circle pic size is the same as the screen size. I would suggest you modify the image size to something like the example I have. You can then set the sprite's position as required and set the physics body to the half of the image containing your semi circle.
Your centerOnNode call should be put in the didEvaluateActions function instead of the didSimulatePhysics function. This is because you need to move the world before the physics are drawn so that they stay in sync. Similar question found here: https://stackoverflow.com/a/24804793/5062806
I have created a SKSpriteNode for a camera with a physic body size of 0.0 , to avoid unwanted collisions and a world node:
-(void)createSceneContents {
SKNode *world = [SKNode node];
world.name = #"world";
self.anchorPoint = CGPointMake(0.1, 0);
SKSpriteNode *camera = [SKSpriteNode spriteNodeWithColor:[UIColor redColor] size:CGSizeMake(300, 300)];
camera.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:CGSizeMake(0, 0)];
camera.physicsBody.affectedByGravity = NO;
camera.physicsBody.usesPreciseCollisionDetection = NO;
camera.physicsBody.categoryBitMask = noColisions;
camera.alpha = 0.5;
camera.zPosition = 1;
camera.name = #"cam";
[self addChild:world];
[world addChild:camera];
I've tried a little tutorial to add a camera in a spriteKit platform game, but i can't even move the view, i don't know hoy to access to the property that move the view. Anybody knows what am i doing wrong?
Here's my code:
-(void)didSimulatePhysics
{
//I've tried with #"cam" and #"hero"
[self centerOnNode: [self childNodeWithName:#"world"]];
}
-(void)centerOnNode:(SKNode *) camera {
CGPoint cameraPositionInScene = [camera.scene convertPoint:camera.position fromNode:camera.parent];
[self.parent setPosition:CGPointMake(
camera.parent.position.x - cameraPositionInScene.x,
camera.parent.position.y - cameraPositionInScene.y
)];
}
In the example from Apple's Documentation, which you are following the camera node isn't an SKSprite, it's an SKNode. I think that will fix your problem.
To answer the question from the title, what you're essentially doing is attaching a world node to the scene. Inside this node, all the sprites are placed. As a child to the world node you add another node for the camera.
This gives you three distinct coordinate systems. Imagine, three sheets of paper, the bottom most one is your world, ie the layer with all the sprites. On top of that is a small piece of paper that represents the camera. Above all of this you have a transparent box that represents your viewing area.
The way it's set up it's impossible to move the top most transparent viewing layer. Instead, what you're doing is moving the point that's sits on top of the world layer and then sliding the world layer to that point.
Now imagine, in the paper scenario, this is a 2D scrolling world where you can only go left and right. Now take the camera point and put it all the way to the right most side of the viewing area. Now, take the world layer and drag it to the left until the camera is in the center of the non-moveable viewing area. That is more or less, what's happening.
In Apple's Adventure sample game they don't move the camera but the "World" SKNode which is the top one.
Excerpt from Apple docs on how they do it:
In Adventure all world-related nodes, including background tiles,
characters, and foliage, are children of a world node, which in turn
is a child of the scene. We change the position of this top-of-tree
world node within the scene to give the effect of moving a camera
across the level. By contrast, the nodes that make up the HUD are
children of a separate node that is a direct child of the scene rather
than of the world node, so that the elements in the HUD don’t move
when we “move the camera.”
Read about it more here
to add the previous answers , you should center on your camera , not the world..
so instead of
[self centerOnNode: [self childNodeWithName:#"world"]];
you should use
[self centerOnNode: [self childNodeWithName:#"cam"]];
and dont forget to change your camera to SKNode instead of SKSprite.
.. and for testing, add a moveTo action on your camera node , move it around back and forth to check if your camera centering works. I recommend putting the call in the touchesbegan
example (put this on your scene where your camera is) :
Put these before the #implementation
#interface yourClassNameHere() // edit this to your own class name
#property SKNode *theWorld;
#property SKNode *theCamera;
#property BOOL cameraRunning;
#end
As you see above, i put the nodes (world and camera) on property of this class, so i dont refer them with node name like you did on your post..
Put this on the Implementation section
// Process Camera centering
-(void) didSimulatePhysics {
[self centerOnNode:self.theCamera];
}
-(void) centerOnNode: (SKNode *) node {
CGPoint pos = [node.scene convertPoint:node.position fromNode:node.parent];
CGPoint p = node.parent.position;
node.parent.position = CGPointMake(p.x - pos.x, p.y-pos.y);
}
// .. Move the camera around when you touch , to see if it works..
-(void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
if (!self.cameraRunning) {
self.cameraRunning = YES;
SKAction *moveUp = [SKAction moveByX:0 y:500 duration:3];
SKAction *moveDown = [SKAction moveByX:0 y:-500 duration:3];
SKAction *moveLeft = [SKAction moveByX:-500 y:0 duration:3];
SKAction *moveRight = [SKAction moveByX:500 y:0 duration:3];
SKAction *sequence = [SKAction sequence:#[moveUp, moveRight,moveDown,moveLeft]];
[self.theCamera runAction:sequence];
} else {
self.cameraRunning = NO;
[self.theCamera removeAllActions];
self.theCamera.position = CGPointZero;
}
}
regards
PS: do you want anchor point 0,0 or 1,1 ? check your anchor point setting there
If you want to move the view, just move the camera:
// Center the view at 100, 0
camera.position = CGPointMake(100, 0);
Here's a slightly longer example here on how to set up a 2D camera system in SpriteKit (in Swift, not ObjC, but easily translated).