I want to set a refernce point in scene, and place object at 5 meters from the reference point on X axis from example. Basically, i want to move an object without tap gesture and just using how many meters in front,right, my object should be put. Can you help me please?
When you first run an ARSession the worldOrigin is set at SCNVector3(0,0,0).
As such you can determine an initial reference point based on this.
For example placing an object 1m to the right of the XAxis, 0m on the YAxis and -1.5 away from the camera would be done like so:
let nodeToAdd = SCNNode()
let nodeGeometry = SCNBox(width: 0.2, height: 0.2, length: 0.2, chamferRadius: 0)
nodeGeometry.firstMaterial?.diffuse.contents = UIColor.cyan
nodeToAdd.geometry = nodeGeometry
nodeToAdd.position = SCNVector3(1, 0, -1.5)
augmentedRealityView.scene.rootNode.addChildNode(nodeToAdd)
You can then move an SCNNode in many ways; with a very simple method being the use of an SCNAction which is:
A simple, reusable animation that changes attributes of any node you attach it to.
Actions which move an SCNNode are as follows:
In our case therefore, let's make use of the class func:
move(to: SCNVector3, duration: TimeInterval)
Which simply moves our node to a new position:
let moveAction = SCNAction.move(to: SCNVector3(1.5, 0, -1.5), duration: 5)
nodeToAdd.runAction(moveAction)
Hope this points you in the right direction.
Related
I am creating a game and I need a set of poles to move from the right side of the screen to the left. once it gets to the left, I need to reset the poles to the beginning and go again in a continuous loop. Create poles simply sets the x position of both poles to the original starting position. The poles move just fine the problem is the looping aspect. I am not sure why the code below will not work. I am very new to swift and admit I am not too sure what I am doing.
movePole()
let create = SKAction.run {
() in
self.createPoles()
self.movePole()
}
let delay = SKAction.wait(forDuration: 10)
let spawn = SKAction.sequence([create,delay])
self.run(SKAction.repeatForever(spawn))
Here's what you need to do:
Tell the poles to move a specific distance for a duration.
Tell the poles to move back to the start point.
Repeat.
As demonstrated here:
let AnimationTime = 5
let PoleTravelDistance = view.frame.width
let MovePolesToLeft = SKAction.move(by: CGVector(dx: PoleTravelDistance, dy: 0), duration: AnimationTime)
let ReturnPolesToRight = SKAction.move(to: CGPoint(x: (POLESNODE.frame.width)/2, y: (POLESNODE.position.y)), duration: 0)
let PoleAnimationSequence = SKAction.sequence([MovePolesToLeft, ReturnPolesToRight])
POLESNODE.run(SKAction.repeatForever(PoleAnimationSequence))
Hope that helps.
I'm trying to calculate SpriteKit overlay content position (not just overlaying visual content) over specific geometry points ARFaceGeometry/ARFaceAnchor.
I'm using SCNSceneRenderer.projectPoint from the calculated world coordinate, but the result is y inverted and not aligned to the camera image:
let vertex4 = vector_float4(0, 0, 0, 1)
let modelMatrix = faceAnchor.transform
let world_vertex4 = simd_mul(modelMatrix, vertex4)
let pt3 = SCNVector3(x: Float(world_vertex4.x),
y: Float(world_vertex4.y),
z: Float(world_vertex4.z))
let sprite_pt = renderer.projectPoint(pt3)
// To visualize sprite_pt
let dot = SKSpriteNode(imageNamed: "dot")
dot.size = CGSize(width: 7, height: 7)
dot.position = CGPoint(x: CGFloat(sprite_pt.x),
y: CGFloat(sprite_pt.y))
overlayScene.addChild(dot)
In my experience, the screen coordinates given by ARKit's projectPoint function are directly usable when drawing to, for example, a CALayer. This means they follow iOS coordinates as described here, where the origin is in the upper left and y is inverted.
SpriteKit has its own coordinate system:
The unit coordinate system places the origin at the bottom left corner of the frame and (1,1) at the top right corner of the frame. A sprite’s anchor point defaults to (0.5,0.5), which corresponds to the center of the frame.
Finally, SKNodes are placed in an SKScene which has its origin on the bottom left. You should ensure that your SKScene is the same size as your actual view, or else the origin may not be at the bottom left of the view and thus your positioning of the node from view coordinates my be incorrect. The answer to this question may help, in particular checking the AspectFit or AspectFill of your view to ensure your scene is being scaled down.
The Scene's origin is in the bottom left and depending on your scene size and scaling it may be off screen. This is where 0,0 is. So every child you add will start there and work its way right and up based on position. A SKSpriteNode has its origin in the center.
So the two basic steps to convert from view coordinates and SpriteKit coordinates would be 1) inverting the y-axis so your origin is in the bottom left, and 2) ensuring that your SKScene frame matches your view frame.
I can test this out more fully in a bit and edit if there are any issues
Found the transformation that works using camera.projectPoint instead of the renderer.projectPoint.
To scale the points correctly on the spritekit: set scaleMode=.aspectFill
I updated https://github.com/AnsonT/ARFaceSpriteKitMapping to demo this.
guard let faceAnchor = anchor as? ARFaceAnchor,
let camera = sceneView.session.currentFrame?.camera,
let sie = overlayScene?.size
else { return }
let modelMatrix = faceAnchor.transform
let vertices = faceAnchor.geometry.vertices
for vertex in vertices {
let vertex4 = vector_float4(vertex.x, vertex.y, vertex.z, 1)
let world_vertex4 = simd_mul(modelMatrix, vertex4)
let world_vector3 = simd_float3(x: world_vertex4.x, y: world_vertex4.y, z: world_vertex4.z)
let pt = camera.projectPoint(world_vector3, orientation: .portrait, viewportSize: size)
let dot = SKSpriteNode(imageNamed: "dot")
dot.size = CGSize(width: 7, height: 7)
dot.position = CGPoint(x: CGFloat(pt.x), y: size.height - CGFloat(pt.y))
overlayScene?.addChild(dot)
}
I have the following code that creates a SCNBox and shoots it on the screen. This works but as soon as I turn the phone in any other direction then the force impulse does not get updated and it always shoots the box in the same old position.
Here is the code:
#objc func tapped(recognizer :UIGestureRecognizer) {
guard let currentFrame = self.sceneView.session.currentFrame else {
return
}
/
let box = SCNBox(width: 0.2, height: 0.2, length: 0.2, chamferRadius: 0)
let material = SCNMaterial()
material.diffuse.contents = UIColor.red
material.lightingModel = .constant
var translation = matrix_identity_float4x4
translation.columns.3.z = -0.01
let node = SCNNode()
node.geometry = box
node.geometry?.materials = [material]
print(currentFrame.camera.transform)
node.physicsBody = SCNPhysicsBody(type: .dynamic, shape: nil)
node.simdTransform = matrix_multiply(currentFrame.camera.transform, translation)
node.physicsBody?.applyForce(SCNVector3(0,2,-10), asImpulse: true)
self.sceneView.scene.rootNode.addChildNode(node)
}
Line 26 is where I apply the force but it does not take into account the user's current phone orientation. How can I fix that?
On line 26 you're passing a constant vector to applyForce. That method takes a vector in world space, so passing a constant vector means you're always applying a force in the same direction — if you want a direction that's based on the direction the camera or something else is pointing, you'll need to calculate a vector based on that direction.
The (new) SCNNode property worldFront might prove helpful here — it gives you the direction a node is pointing, automatically converted to world space, so it's useful with physics methods. (Though you might want to scale it.)
The movement of a physics body circle is too erratic for what I want to achieve. I would like to restrict it so it follows a certain path touching specific points (or a range of points) as shown in the image below. How can I set the physics properties to traverse a similar path?
how to set physics properties for a circle so it follows given path
So essentially you are looking to move a node to a particular point using real-time motion. I have an answer here showing how to do this, however given the number of up votes this question has received, I will provide a more detailed answer.
What the answer I linked to doesn't provide is traversing a path of points. So below I have provided a solution showing how this can be done below. It simply just moves to each point in the path, and each time the node reaches a point, we increment the index to move to the next point. I also added a few variables for travel speed, rate (to make the motion more smooth or static) and whether or not the node should repeat the path. You could further expand upon this solution to better meet the needs of your game. I would definitely consider subclassing a node and building this behavior into it so you can re-use this motion for multiple nodes.
One final note, you may notice the calculation for the impulse varies between my solution below and the answer I linked to above. This is because I am avoiding using angle calculation because they are very expensive. Instead I am calculating a normal so that the calculation is more computationally efficient.
One final note, my answer here explains the use of the rate factor to smooth the motion and leave room for motion distortions.
import SpriteKit
class GameScene: SKScene {
var node: SKShapeNode! //The node.
let path: [CGPoint] = [CGPoint(x: 100, y: 100),CGPoint(x: 100, y: 300),CGPoint(x: 300, y: 300),CGPoint(x: 300, y: 100)] //The path of points to travel.
let repeats: Bool = true //Whether to repeat the path.
var pathIndex = 0 //The index of the current point to travel.
let pointRadius: CGFloat = 10 //How close the node must be to reach the destination point.
let travelSpeed: CGFloat = 200 //Speed the node will travel at.
let rate: CGFloat = 0.5 //Motion smoothing.
override func didMoveToView(view: SKView) {
node = SKShapeNode(circleOfRadius: 10)
node.physicsBody = SKPhysicsBody(circleOfRadius: 10)
node.physicsBody!.affectedByGravity = false
self.addChild(node)
}
final func didReachPoint() {
//We reached a point!
pathIndex++
if pathIndex >= path.count && repeats {
pathIndex = 0
}
}
override func update(currentTime: NSTimeInterval) {
if pathIndex >= 0 && pathIndex < path.count {
let destination = path[pathIndex]
let displacement = CGVector(dx: destination.x-node.position.x, dy: destination.y-node.position.y)
let radius = sqrt(displacement.dx*displacement.dx+displacement.dy*displacement.dy)
let normal = CGVector(dx: displacement.dx/radius, dy: displacement.dy/radius)
let impulse = CGVector(dx: normal.dx*travelSpeed, dy: normal.dy*travelSpeed)
let relativeVelocity = CGVector(dx:impulse.dx-node.physicsBody!.velocity.dx, dy:impulse.dy-node.physicsBody!.velocity.dy);
node.physicsBody!.velocity=CGVectorMake(node.physicsBody!.velocity.dx+relativeVelocity.dx*rate, node.physicsBody!.velocity.dy+relativeVelocity.dy*rate);
if radius < pointRadius {
didReachPoint()
}
}
}
}
I did this pretty quickly so I apologize if there is a mistake. I don't have time now but I will add a gif showing the solution later.
A note about collisions
To fix the erratic movement during a collision, after the 2 bodies collide set the "rate" property to 0 or preferably a very low number to reduce the travel velocity impulse which will give you more room for motion distortion. Then at some point in the future (maybe some time after the collision occurs or preferably when the body is moving slow again) set the rate back to its initial value. If you really want a nice effect, you can actually ramp up the rate value over time from 0 to the initial value to give yourself a smooth and gradual acceleration.
Quick implementation using followPath:duration:
override func didMoveToView(view: SKView) {
self.backgroundColor = UIColor.blackColor()
let xWidth: CGFloat = CGRectGetMaxX(self.frame)
let yHeight: CGFloat = CGRectGetMaxY(self.frame)
let ball = SKSpriteNode(color: UIColor.redColor(), size: CGSizeMake(50.0, 50.0))
let offset : CGFloat = ball.size.width / 2
// Moving path
let path = CGPathCreateMutable()
CGPathMoveToPoint(path, nil, offset, yHeight / 2)
CGPathAddLineToPoint(path, nil, xWidth * 2 / 3, yHeight - offset)
CGPathAddLineToPoint(path, nil, xWidth - offset, yHeight * 2 / 3)
CGPathAddLineToPoint(path, nil, xWidth / 2, offset)
CGPathAddLineToPoint(path, nil, offset, yHeight / 2)
// Movement
let moveByPath = SKAction.followPath(path, asOffset: false, orientToPath: false, duration: 4.0)
let moveForever = SKAction.repeatActionForever(moveByPath)
ball.runAction(moveForever)
self.addChild(ball)
}
In GameViewController.swift, I changed the default GameScene.unarchiveFromFile method to let scene = GameScene(size: view.bounds.size) for creating the scene's size.
Preview:
I'm trying to create an ellipse in the center of my scene:
let center = (CGRectGetMidX(view.scene.frame), CGRectGetMidY(view.scene.frame))
let size = (view.scene.frame.size.width * 0.3, view.scene.frame.size.height * 0.3)
let ellipse = SKShapeNode (ellipseInRect: CGRectMake(center.0, center.1, size.0, size.1))
ellipse.strokeColor = UIColor.blackColor()
ellipse.position = CGPointMake(center)
self.addChild(ellipse)
This was added to didMoveToView, and the node count on the view shows 1, but I do not see the path. How do I add an ellipse to my scene using the SKShapeNode ellipseInRect API?
The problem lies in ellipse.position = CGPointMake(center). For some reason, this changes the position of the ellipse relative to itself rather than relative to the view - so if you did ellipse.position = CGPoint(x: 100, y: 100) then it would set the position to 100 up and 100 to the right of the ellipse itself as opposed to 100,100 on the scene. If you comment out this line, then you should be able to see you ellipse on the screen - I certainly could when it tried it. Hope that helps you position it to where you want.