I am trying to set angle constraints for body parts in Swift 2.0.
I have tried to automatically set them in the scene editor under IK Constraints and this failed.
I subsequently set them in the code:
lowerArmBack.reachConstraints?.lowerAngleLimit = 0
lowerArmBack.reachConstraints?.upperAngleLimit = CGFloat(10)
Neither has worked (with or without CGFloat). I am trying to follow this tutorial: http://www.raywenderlich.com/80917/sprite-kit-inverse-kinematics-swift but have stumbled in to issues since the Swift update.
Essentially I want to limit angles to prevent the arms moving in all 360 degrees but this isn't happening.
You need to set a zRotation constraint with a range for the body part you want:
let range = SKRange(lowerLimit: CGFloat(0).degreesToRadians(),
upperLimit: CGFloat(160).degreesToRadians())
let rotationConstraint = SKConstraint.zRotation(range)
lowerArmFront.constraints = [rotationConstraint]
Regarding the tutorial, I'm actually working on it's update fixing the issue.
You can also add a SKReachConstraint in the following way:
lowerLeg.reachConstraints = SKReachConstraints(lowerAngleLimit: CGFloat(-45).degreesToRadians(), upperAngleLimit: 0)
upperLeg.reachConstraints = SKReachConstraints(lowerAngleLimit: CGFloat(-45).degreesToRadians(), upperAngleLimit: CGFloat(160).degreesToRadians())
Hope it helps!
Related
I've been trying to implement an infinite background animation, which should change between 4 images of equal height and then repeat the sequence. However, it does not seem to work properly.
Note anchorPoint = CGPoint(x: 0.5, y: 0)
func updateBackground(currentTime: TimeInterval){
var delta: CGFloat = 0.0
if lastUpdate != nil {
delta = CGFloat(currentTime - lastUpdate)
}
//First increment position
activeBackground1.position.y += delta*backgroundVelocity
activeBackground2.position.y += delta*backgroundVelocity
//Detect bounds surpass
if activeBackground1.position.y > activeBackground1.size.height + screen.height/2 {
lastSky = (lastSky + 1)%4
sky1 = SKTexture(imageNamed: "sky" + String(lastSky))
activeBackground1.texture = sky1
//Reposition: background1 new position is equal to minus the entire height of
//background2 + its y size.
activeBackground1.position.y = -abs(activeBackground2.size.height-activeBackground2.position.y)
}
if activeBackground2.position.y > activeBackground2.size.height + screen.height/2 {
lastSky = (lastSky + 1)%4
sky1 = SKTexture(imageNamed: "sky" + String(lastSky))
activeBackground2.texture = sky1
activeBackground2.position.y = -abs(activeBackground1.size.height-activeBackground1.position.y)
}
}
The update algorithm works fine, but when it is needed to reposition one of the two background, it seems there is an offset of about 10.0 CGFloat from one background to another. What am I doing wrong?
EDIT: It turned out that the error was located in my image, which presented some blank rows and therefore generated visualisation glitches. So my code works perfectly.
I do the test and most likely you should use something like:
activeBackground2.position.y = activeBackground1.size.height + activeBackground1.position.y
instead of
activeBackground2.position.y = -abs(activeBackground1.size.height-activeBackground1.position.y)
I did this example and it works correctly: https://github.com/Maetschl/SpriteKitExamples/tree/master/InfiniteBackground/InfiniteBackground
Feel free to see and use.
Your problem is floating point math causing rounding errors. I am on a phone right now so I can’t wrote code, but what you want to do is have 1 parent SKNode to handle your entire background.
Add your background slivers to the parent node.
You then place the moving action on the parent only.
As each sliver leaves the screen, you take the sliver, and move it to the end of the other slivers.
This jumping should always be done with integer math, leaving no holes.
Basically:
The floating point moving math is done on the parent node.
The integer based tile jumping is done on each of the slivers.
Edit: I have been able to solve this problem by using PhysicsEditor to make a polygonal physicsbody instead of using SKPhysicsBody(... alphaThreshold: ... )
--
For some reason I'm having trouble with what I'm assuming is SKPhysicBodies being slightly off-place. While using showPhysics my stationary obstacle nodes appear to have their physicbodies in the correct position, however I am able to trigger collisions without actually touching the obstacle. If you look at the image below it shows where I have found the physicsbodies to be off centre, despite showPhysics telling me otherwise. (Note, the player node travels in the middle of these obstacle nodes).
I also thought it would be worth noting that while the player is travelling, its physicbody appears to travel slightly ahead but I figured this is probably normal.
I also use SKPhysicsBody(... alphaThreshold: ... ) to create the physicbodies from .png images.
Cheers.
Edit: Here's how I create the obstacle physicbodies. Once they're added into the worldNode they are left alone until they need to be removed. Apart from that I don't change them in any way.
let obstacleNode = SKSpriteNode(imageNamed: ... )
obstacleNode.position = CGPoint(x: ..., y: ...)
obstacleNode.name = "obstacle"
obstacleNode.physicsBody = SKPhysicsBody(texture: obstacleNode.texture!, alphaThreshold: 0.1, size: CGSize(width: obstacleNode.texture!.size().width, height: obstacleNode.texture!.size().height))
obstacleNode.physicsBody?.affectedByGravity = false
obstacleNode.physicsBody?.isDynamic = false
obstacleNode.physicsBody!.categoryBitMask = CC.wall.rawValue
obstacleNode.physicsBody!.collisionBitMask = CC.player.rawValue
obstacleNode.physicsBody!.contactTestBitMask = CC.player.rawValue
worldNode.addChild(obstacleNode)
The player node is treated the same way, here is how the player moves.
playerNode.physicsBody?.velocity = CGVector(dx: dx, dy: dy)
I'm assuming you aren't showing the exact images that you used to create your SKSpriteNode and SKPhysicsBody instances. Since you are using a texture to define the shape of your SKPhysicsBody you are likely running up against this:
SKPhysicsBody documentation
If you do not want to create your own shapes, you can use SpriteKit to create a shape for you based on the sprite’s texture.
This is easy and convenient but it can sometimes give unexpected results depending on the textures you are using for your sprite. Perhaps try making an explicit mask or using a simple shape to represent your physics body. There are very good examples and guidelines in that documentation.
I would also follow this pattern when you set the properties on your objects:
// safely unwrap and handle failure if it fails
guard let texture = obstacleNode.texture else { return }
// create the physics body
let physicsBody = SKPhysicsBody(texture: texture,
alphaThreshold: 0.1,
size: CGSize(width: texture.size().width,
height: texture.size().height))
// safely set its properties without the need to unwrap an Optional
physicsBody.affectedByGravity = false
// set the rest of the properties
// set the physics body property on the node
obstacleNode.physicsBody = physicsBody
By setting the properties on a concrete instance of SKPhysicsBody and fully unwrapping and testing Optionals you minimize the chances for a run-time crash that may be difficult to debug.
Hello I'm trying to spawn bullets at the bottom of my screen to travel upwards but the current code that I have spawns the bullets at the top of the screen. I've tried making the height negative and nothing happened. Here's the code I'm working with, thanks.
let randomBulletPosition = GKRandomDistribution(lowestValue: -300, highestValue: 300)
let position = CGFloat(randomBulletPosition.nextInt())
bullet.position = CGPoint(x: position, y: self.frame.size.height + bullet.size.height)
Some nice conversions will help you.
Now, do not do this all the time, this should be a one and done type deal, like in a lazy property.
First, we want to get the bottom of our view
let viewBottom = CGPoint(x:scene!.view!.midX,y:scene!.view!.frame.maxY) //In a UIView, 0,0 is the top left corner, so we look to bottom middle
Second, we want to convert the position to the scene
let sceneBottom = scene!.view!.convert(viewBottom, to:scene!)
Finally we want to convert to whatever node you need it to be a part of. (This is optional if you want to place it on the scene)
let nodeBottom = scene!.convert(sceneBottom,to:node)
Code should look like this:
let viewBottom = CGPoint(x:scene!.view!.midX,y:scene!.view!.frame.maxY)
let sceneBottom = scene!.view!.convert(viewBottom!, to:scene!)
let nodeBottom = scene!.convert(sceneBottom,to:node)
Of course, this is a little ugly.
Thankfully we have convertPoint and convert(_from:) to clean things up a little bit
let sceneBottom = scene.convertPoint(from:viewBottom)
Which means we can clean up the code to look like this:
let sceneBottom = scene.convertPoint(from:CGPoint(x:scene!.view!.midX,y:scene!.view!.frame.maxY))
let nodeBottom = node.convert(sceneBottom,from:scene!)
Then we can make it 1 line as:
let nodeBottom = node.convert(scene.convertPoint(from:CGPoint(x:scene!.view!.midX,y:scene!.view!.frame.maxY),from:scene!)
As long as the node is available to the class, we can make it lazy:
lazy var nodeBottom = self.node.convert(self.scene!.convertPoint(CGPoint(x:self.scene!.view!.midX,y:self.scene!.view!.frame.maxY),from:self.scene!)
This means the first time you call nodeBottom, it will do these calculations for you and store it into memory. Everytime after that, the number is preserved.
Now that you know where the bottom of the screen is in the coordinate system you want to use, you can assign the x value to whatever your random is producing, and you can subtract the (node.height * (1 - node.anchorPoint.y)) to fully hide your node from the scene.
Now keep in mind, if your node moves between various parents, this lazy will not update.
Also note, I unwrapped all optionals with !, you may want to be using ? and checking if it exists first.
I currently have two SKSpriteNodes on top of each other like so (The white part is one and the brown round circle part is the other one):
The white part is positioned 1/3 the way down on top of the round brown sprite node. In the picture, the brown round part has a SKPhysicsBody applied to it already as seen by the light blue outline around it. When I add a SKPhysicsBody around the top ovalish white part it pushes it up and not in the position I wanted it.
How can I have a SKPhysics body coving both bodies of sprites but not have the physics bodies push on one another which makes the white part move upwards? I would like the white part to stay in the position it was in the first image.
Thanks for anyone help!
Here's the code I used for the SKPhysicsBody's:
// create, position, scale & add the round body
roundBody = SKSpriteNode( imageNamed: "roundBody" )
roundBody.position = CGPoint( x: 207, y: 70 )
roundBody.zPosition = 1
roundBody.xScale = 0.3
roundBody.yScale = 0.3
// add sprite node to view
self.addChild( roundBody )
// create, position, scale & add the head
theHead!.position = CGPoint( x: 207, y: roundBody.frame.maxY / 1.15 )
theHead!.zPosition = 2
theHead!.xScale = 0.3
theHead!.yScale = 0.3
// setting up a SKPhysicsBody for the round body
roundBody.physicsBody = SKPhysicsBody( circleOfRadius: roundBody.size.width / 4 )
roundBody.physicsBody!.dynamic = true
roundBody.physicsBody!.affectedByGravity = true
roundBody.physicsBody!.allowsRotation = false
roundBody.physicsBody!.pinned = false
// setting up a SKPhysicsBody for the head
theHead!.physicsBody = SKPhysicsBody(circleOfRadius: theHead!.size.width / 2 )
theHead!.physicsBody!.dynamic = true
theHead!.physicsBody!.affectedByGravity = false
theHead!.physicsBody!.allowsRotation = false
theHead!.physicsBody!.pinned = false
I was able to figure out that if you use SKPhysicsJointPin it does the exact thing I needed! (Which was to basically pin a sprite head on it's body and share a physics body)
let joinTogether = SKPhysicsJointPin.jointWithBodyA(
roundBody.physicsBody!,
bodyB:theHead!.physicsBody!,
anchor: GPointMake(CGRectGetMidX(roundBody.frame),
CGRectGetMinY(theHead!.frame)))
scene!.physicsWorld.addJoint(joint)
Hope this helps someone in the future!
If you never want it to move, set it's .dynamic property to false. Then other objects may or may not bounce/collide with it (depending upon their collisionBitMask) but it won't move in response to those collisions.
Your own answer is correct and a better solution but just to explain further.
The reason of the bodies colliding is that by default a physics body's collision bit mask is set to all categories which means it will collide with everything. In your code you are not calling
roundBody.physicsBody?.collisionBitMask = ...
which is why its using the default values.
To change that you could give your body and head a different collisionBitMask.
Im sure you will deal with this sooner or later when you handle collisions
Also as a tip it's a better idea to not force unwrap the physics bodies unless you have too, even though you know they exist. So you should replace your ! with ? whenever possible.
I have 4 nodes of enemies. They are appearing on a scene from the right to the left bound. But often they are appearing in groups for some reason. It looks unpleasantly so I want to set the distance between them. I know that I can do it with SKConstraint, but XCode says that I'm doing something wrong. That's how I tried to do it:
mouse = SKSpriteNode(texture: mouseArray[0]);
self.mouse.position = CGPointMake(CGRectGetMaxX(self.frame) + self.mouse.size.width, CGRectGetMidY(self.frame) - 138)
self.mouse.size = CGSizeMake(self.mouse.size.width + self.mouse.size.width / 2, self.mouse.size.height + mouse.size.height / 2)
let constraint = SKConstraint.distance(range: 50...100, toNode: cat)
Xcode tells me that argument for parameter ToPoint is missing. I don't know why and what point it is talking about.
I couldn't find examples of using SKConstraint.distance online. How to use constraints properly for this purpose? Thanks!
SKConstraint's distance class method takes an SKRange as its first argument not a closed range (e.g., 10...50). For an example,
Swift 2
let range = SKRange(lowerLimit:50, upperLimit:100)
let constraint = SKConstraint.distance(range, toNode:cat)
mouse.constraints = [constraint]
Swift 3
let range = SKRange(lowerLimit:50, upperLimit:100)
let constraint = SKConstraint.distance(range, to: cat)
mouse.constraints = [constraint]