I am creating a game where I do not want the player to be able to move out of the screen. The node follows the players moving touch. The code I have "under construction" so the player can't move out on the top or right side, but I do not want the player to be able to move out on any of the sides.
- (void)movementPlayer {
SKAction * actionMoveX = [SKAction moveToX:MIN(location2.x - playerPositionX, self.size.width - (_player.size.width/2)) duration:0];
SKAction * actionMoveY = [SKAction moveToY:MIN(location2.y - playerPositionY, self.size.height - (_player.size.height/2)) duration:0];
[_player runAction:[SKAction sequence:#[actionMoveX, actionMoveY]]];
}
You should create a physics world and add a border rectangle around the screen. This border must have a physics body that is set to collide with the physics body collision category given to your player node. If the player node starts inside the border, the player cannot leave the screen and no additional coding is required (besides properly setting up collision categories for each physics body)
RayWenderlich.com has easy to understand game tutorials that show how to handle collisions following the sprite kit manual.
In your SKScene:
self.physicsBody=[SKPhysicsBody bodyWithEdgeLoopFromRect:self.frame];
self.physicsWorld.gravity=CGVectorMake=(0,0);
_player.physicsBody=[SKPhysicsBody bodyWithRectangleOfSize:CGSizeMake(10,10)];//example; use bodyWithPolygonFromPath:yourCGPath if player has more complex form, or bodyWithCircleOfRadius:radius if its shape is circle
_player.physicsBody.velocity=CGVectorMake(10,10); //or more then 10,10
Good luck!
just add the bottom code to your method that is called it should stop all physical bodies from leaving the screen!! veryuseful!
SKPhysicsBody* gameborderBody = [SKPhysicsBody bodyWithEdgeLoopFromRect:self.frame];
// 2 Set physicsBody of scene to borderBody
self.physicsBody = gameborderBody;
// 3 Set the friction of that physicsBody to 0
self.physicsBody.friction = 1.0f;
Related
I have a Class with a SpriteNode that rotates very wide, when rotated within the main Scene(as if the anchor point is in the middle of the screen and the Sprite is rotating around it). I want it to rotate around the anchor point of itself in the main Scene(anchor point on the Sprite).
So in the Class i have something like the following
- (void)createChainWithPos:(CGPoint)pos {
SKTexture *myTex...
SKTexture *myTex2...
SKSpriteNode *chainFront = [SKSpriteNode spriteWithTexture:myTex];
chainFront.position = pos;
chainFront.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:mytex.size];
[self addChild:chainFront];
[_chainParts addObject:chainFront];
SKSpriteNode *chainSide = [SKSpriteNode spriteWithTexture:myTex2];
chainSide.position = CGPointMake(chainFront.position.x, chainFront.position.y - chainSide.size.height + 6);
chainSide.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:myTex2.size;
[self addChild:chainSide];
[_chainParts addObject:chainSide];
}
I have an loop creating the chain parts in the main file but couldn't get it rotate so stripped it down in an new project. There is actually 4 chain parts but i only did two. The other two are just mirrors of the ones above with their positions mirroring the chainSide.(to position them in a chain like fashion)
and in the Scene
self.chain1 = [chain node];
[self.chain1 createChainWithPos:CGPointMake(self.size.width/2, self.size.height/2);
self.chain1.zRotation = 3.14/4;
[self addChild:self.chain1];
I have a NSMutableArray in the chain class header that i use to hold the chains.
the physics joints
for (int i = 1; i < self.chain1.chainParts.count; i++ {
SKSpriteNode *nodeA = [[self.chain1 chainParts]objectAtindex:i-1];
SKSpriteNode *nodeB = [[self.chain1 chainParts]objectAtindex:i];
SKPhysicsJointPin *pin = [SKPhysicsJointPin jointWithBodyA:nodeA.physicsBody
bodyB:nodeB.physicsBody
anchor:CGPointMake(CGRectGetMidX(nodeA.frame), CGRectGetMinY(nodeA.Frame))];
}
I found that if i set the position of the chain in the middle in the Class, it rotates correctly in the Scene. However, the physics joints just start moving randomly across the screen and isn't correct to the anchor points set. (the physics joints are set in the Scene)
I don't know if i have to convert the coordinates or play with random anchor point positions , but if someone could shed some light if would be greatly appreciated.
You do not want to use the nodes frame, you want to use the nodes size, the frame mid is the screen coordinate + the fitted node size / 2, you want the middle of your sprite only, also for pi / 4 use M_PI_4
Hi I have a bunch of round SKSpriteNodes with a circle physical body. Now when these balls roll down a path I want some of these SKSpritenodes image to stay upright even when rolling. So think of an arrow pointing upwards. When the ball starts rolling the arrow spins in circles. But for some balls Id like the arrow to remain pointing up even when the ball rolls. Whats the best way of doing this?
Edit
So an answer was given but from testing it turns out it is not the correct one. Not allowing the ball to rotate affects the way it rolls down the path. So I guess what I want is rotation to be on but the image to always appear to the user like its not rotating. Thanks.
This looks like a job for SupermSKConstraint. Constraints are evaluated and applied after the physics simulation runs on each frame, so you can use them for tasks like making a node point a certain direction regardless of what physics does to it. For this, you'd want a zRotation constraint.
But there's a bit more to it than that. If you set a zero-rotation constraint on the ball:
// Swift
let constraint = SKConstraint.zRotation(SKRange(constantValue: 0))
ball.constraints = [constraint]
You'll find that SpriteKit resets the physics body's transform every frame due to the constraint, so it only sort-of behaves like it's rolling. Probably not what you want. (To get a better idea what's going on here, try adding a zero-rotation constraint to a rectangular physics body in a world without gravity, applying an angular impulse to it, and watching it try to spin in a view with showsPhysics turned on. You'll see the sprite and its physics body get out of sync and shake a bit -- probably due to accumulated rounding errors as the physics engine and the constraint engine fight it out.)
Instead, you can do a bit of what's in 0x141E's answer, but use constraints to make it less code (and run more efficiently):
Give the ball node a circular physics body. (And possibly no texture, if the only art you want for the ball is a non-rotating sprite.)
Add the arrow node as a child of the ball node. (It doesn't need its own physics body.)
Put a zero-rotation constraint on the arrow.
Wait, that doesn't work -- I told the arrow to not rotate, but it's still spinning?! Remember that child nodes are positioned (and rotated and scaled) relative to their parent node. So the arrow isn't spinning relative to the ball, but the ball is spinning. Don't worry, you can still solve this with a constraint:
Tell the constraint to operate relative to the node containing the ball (probably the scene).
Now the constraint will keep the arrow in place while allowing the ball to rotate however the physics simulation wants it to.
Here's some test code to illustrate:
// Step 1: A rectangular spinner so we can see the rotation
// more easily than with a ball
let spinner = SKSpriteNode(color: SKColor.redColor(), size: CGSize(width: 300, height: 20))
spinner.position.x = scene.frame.midX
spinner.position.y = scene.frame.midY
spinner.physicsBody = SKPhysicsBody(rectangleOfSize: spinner.size)
scene.addChild(spinner)
spinner.physicsBody?.applyAngularImpulse(0.1) // wheeeeee
// Step 2: Make the arrow a child of the spinner
let arrow = SKSpriteNode(color: SKColor.greenColor(), size: CGSize(width: 20, height: 50))
spinner.addChild(arrow)
// Step 3: Constrain the arrow's rotation...
let constraint = SKConstraint.zRotation(SKRange(constantValue: 0))
arrow.constraints = [constraint]
// Step 4: ...relative to the scene, instead of to its parent
constraint.referenceNode = scene
Here are two methods to create a ball with a physics body and an arrow:
Add an arrow as a child of a ball
Add both the ball and the arrow directly to the scene
Here's what will happen when you add the above to the SpriteKit simulation:
The arrow will rotate when the ball rotates
Both the arrow and the ball will move/rotate independently
If you want the arrow to rotate with the ball, choose Option 1. If you want the arrow to remain fixed, choose Option 2. If you choose Option 2, you will need to adjust the rotation of the arrow to ensure that it points upward. Here's an example of how to do that.
-(void)didMoveToView:(SKView *)view {
self.scaleMode = SKSceneScaleModeResizeFill;
/* Create an edge around the scene */
self.physicsBody = [SKPhysicsBody bodyWithEdgeLoopFromRect:view.frame];
// Show outline of all physics bodies
self.view.showsPhysics = YES;
CGFloat radius = 16;
SKNode *balls = [SKNode node];
balls.name = #"balls";
[self addChild:balls];
// Create 5 balls with stationary arrows
for (int i = 0;i<5;i++) {
// Create a shape node with a circular physics body. If you are targeting iOS 8,
// you have other options to create circular node. You can also create an SKSpriteNode
// with a texture
SKShapeNode *ball = [SKShapeNode node];
// Create a CGPath that is centered
ball.path = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(-radius,-radius,radius*2,radius*2)].CGPath;
ball.fillColor = [SKColor whiteColor];
ball.position = CGPointMake(100, 100+i*radius*2);
ball.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius:radius];
[balls addChild:ball];
// Create an arrow node
CGSize size = CGSizeMake(2, radius*2);
SKSpriteNode *arrow = [SKSpriteNode spriteNodeWithColor:[SKColor blackColor] size:size];
arrow.name = #"arrow";
arrow.position = CGPointZero;
[ball addChild:arrow];
// Apply angular impulse to the ball so it spins when it hits the floor
[ball.physicsBody applyAngularImpulse:-1];
}
}
- (void) didSimulatePhysics
{
SKNode *balls = [self childNodeWithName:#"balls"];
for (SKNode *ball in balls.children) {
SKNode *arrow = [ball childNodeWithName:#"arrow"];
arrow.zRotation = -ball.zRotation;
}
}
sprite.physicsBody.allowsRotation = NO;
The allowRotation property should control exactly what you are asking.
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 am working on an iOS game using Sprite Kit.
I recently added an SKSpriteNode into my scene and did NOT create a physics body for it. However, when I build and run, when the player's character(which does have a physics body) moves into the SKSpriteNode, it spins and moves away, like it has a physics body -but I didn't create one for the SKSpriteNode.
Even if I type
sprite.physicsBody = nil;
it still behaves like it's part of the simulation.
I wondered if a physics body is created automatically when you make an SKSpriteNode, but I looked at the documentation and searched it on Google and couldn't find anything to suggest that is the case.
Any help or suggestions would be much appreciated.
This is the code I used to create the sprite (the one that should not be affected by the simulation)
-(void)addSprite
{
SKSpriteNode *sprite = [SKSpriteNode spriteNodeWithImageNamed:#"image"];
sprite.position = CGPointMake(40, 30);
sprite.zPosition = 30;
sprite.name = #"spriteName";
[self addChild:sprite];
}
In another part of the project I have
[self addSprite];
to call the method.
Yes every SKSpriteNode comes with a physics body. Its best to change the physics body's properties instead of getting rid of it altogether. If you want your sprite to be on screen and not interact with any other sprite nodes, do the following:
sprite.physicsBody.dynamic = NO;
sprite.physicsBody.collisionBitMask = 0x0;
sprite.physicsBody.contactTestBitMask = 0x0;
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).