trouble getting collision point - ios

Hey I'm trying to get the point of collision and then create a joint at that point for two nodes. I'm not sure what my results mean or how to get what I want.
I don't have access to the contact points which I see in other posts. The CCContactSet from the collision only gives me number of points and normal.
I output the normal during collision begin and its (1.0, -0.0) for left wall, (-0.0, 1.0) for bottom wall, (-1.0, 0.0) for right wall, (-0.0, -1.0) for top wall. I don't understand them basically. I know they are only referring to the second hullPiece though because no matter how I rotate or position the booster during the collision, the results stay the same. They only change if I rotate the hullPiece.
So how do I get the contact points to create the joint? Am I supposed to use the normal for that, and if so how?
newSprite = CCSprite(imageNamed: "Booster.png")
newSprite.position = CGPoint(x: 200, y: 200)
newSprite.scale = 4.0
let spritePhysics = CCPhysicsBody(rect: newSprite.textureRect, cornerRadius: 0)
spritePhysics.collisionType = "booster"
spritePhysics.sensor = true
newSprite.physicsBody = spritePhysics
editorPhysics.addChild(newSprite)
newSprite2 = CCSprite(imageNamed: "HullPiece.png")
newSprite2.position = CGPoint(x: 200, y: 200)
newSprite2.scale = 4.0
let spritePhysics2 = CCPhysicsBody(rect: newSprite2.textureRect, cornerRadius: 0)
spritePhysics2.collisionType = "hull"
spritePhysics2.sensor = true
newSprite2.physicsBody = spritePhysics2
editorPhysics.addChild(newSprite2)
func ccPhysicsCollisionBegin(pair: CCPhysicsCollisionPair!, booster: CCNode!, hull: CCNode!) -> ObjCBool
{
NSLog("contact point\(pair.contacts.count) \(pair.contacts.normal)")
return true
}

You get access to the contact points through the contacts property of the CCPhysicsCollisionPair.
Here's what the contacts struct looks like:
typedef struct CCContactSet {
/// The number of contact points in the set.
/// The count will always be 1 or 2.
int count;
/// The normal of the contact points.
CGPoint normal;
/// The array of contact points.
struct {
/// The absolute position of the contact on the surface of each shape.
CGPoint pointA, pointB;
/// Penetration distance of the two shapes.
/// The value will always be negative.
CGFloat distance;
} points[2];
} CCContactSet;
Through the points array you can access the exact collision position for each involved shape.

Related

Find SKNodes in a specified area

I would like to be able to do something similar to the nodes(at:) function in SpriteKit. However, for my use case, checking if there are SKNodes at one specific CGPoint is simply too specific.
What I would like to have, is an area, (that I can specify), similar to the nodes(at:) function, where I get back the array of nodes intersecting the specific area.
Is there some function that does this for me? Also, I would prefer not to bring any SpriteKit Physics into this.
what you are looking for is
func intersects(_ node: SKNode) -> Bool
Returns a Boolean value that indicates whether this node intersects the specified node. The two nodes are considered to intersect if their frames intersect. The children of both nodes are ignored in this test.
example...
//sprite created in Scene editor
if let locationBox = self.childNode(withName: "locationBox") as? SKSpriteNode {
self.locationBox = locationBox
}
or
//sprite created programmatically
let locationBox = SKSpriteNode(color: .red, size: CGSize(width: 300, height: 300))
locationBox.zPosition = 1
locationBox.position = CGPoint(x: 100, y: 100)
addChild(locationBox)
checking for intersects
for child in children {
if locationBox.intersects(child) {
print("child.name \(child.name)")
}
}

ARkit - Camera Position and 3D model Positions

I am trying to put several models in the scene.
for candidate in selectedCandidate {
sceneView.scene.rootNode.addChildNode(selectedObjects[candidate])
}
The candidate and selectedCandidate stands for the index of the model I want to use. Each model contains a rootNode and nodes attached to it. I use the API worldPosition and position of SCNNode to get and modify 3D model's position.
The thing I want to do is put those models right in front users' eyes. It means I need to get the camera's position and orientation vector to put the models in the right position I want. I also use these codes to get the camera's position according to this solution https://stackoverflow.com/a/47241952/7772038:
guard let pointOfView = sceneView.pointOfView else { return }
let transform = pointOfView.transform
let orientation = SCNVector3(-transform.m31, -transform.m32, transform.m33)
let location = SCNVector3(transform.m41, transform.m42, transform.m43)
The PROBLEM is that the camera's position and the model's position I printed out directly are severely different in order of magnitude. Camera's position is 10^-2 level like {0.038..., 0.047..., 0.024...} BUT the model's position is 10^2 level like {197.28, 100.29, -79.25}. From my point of view when I run the program, I am in the middle of those models and models are very near, but the positions are so different. So can you tell me how to modify the model's position to whatever I want? I really need to put the model right in front of user's eyes. If I simply do addChildNode() the models are behind me or somewhere else, while I need the model just be in front of users' eyes. Thank you in advance!
If you want to place an SCNNode infront of the camera you can do so like this:
/// Adds An SCNNode 3m Away From The Current Frame Of The Camera
func addNodeInFrontOfCamera(){
guard let currentTransform = augmentedRealitySession.currentFrame?.camera.transform else { return }
let nodeToAdd = SCNNode()
let boxGeometry = SCNBox(width: 0.1, height: 0.1, length: 0.1, chamferRadius: 0)
boxGeometry.firstMaterial?.diffuse.contents = UIColor.red
nodeToAdd.geometry = boxGeometry
var translation = matrix_identity_float4x4
//Change The X Value
translation.columns.3.x = 0
//Change The Y Value
translation.columns.3.y = 0
//Change The Z Value
translation.columns.3.z = -3
nodeToAdd.simdTransform = matrix_multiply(currentTransform, translation)
augmentedRealityView?.scene.rootNode.addChildNode(nodeToAdd)
}
And you can change any of the X,Y,Z values as you need.
Hope it points you in the right direction...
Update:
If you have multiple nodes e.g. in a scene, in order to use this function, it's probably best to create a 'holder' node, and then add all your content as a child.
Which means then you can simply call this function on the holder node.

Correctly position the camera when panning

I'm having a hard time setting boundaries and positioning camera properly inside my view after panning. So here's my scenario.
I have a node that is bigger than the screen and I want to let user pan around to see the full map. My node is 1000 by 1400 when the view is 640 by 1136. Sprites inside the map node have the default anchor point.
Then I've added a camera to the map node and set it's position to (0.5, 0.5).
Now I'm wondering if I should be changing the position of the camera or the map node when the user pans the screen ? The first approach seems to be problematic, since I can't simply add translation to the camera position because position is defined as (0.5, 0.5) and translation values are way bigger than that. So I tried multiplying/dividing it by the screen size but that doesn't seem to work. Is the second approach better ?
var map = Map(size: CGSize(width: 1000, height: 1400))
override func didMove(to view: SKView) {
(...)
let pan = UIPanGestureRecognizer(target: self, action: #selector(panned(sender:)))
view.addGestureRecognizer(pan)
self.anchorPoint = CGPoint.zero
self.cam = SKCameraNode()
self.cam.name = "camera"
self.camera = cam
self.addChild(map)
self.map.addChild(self.cam!)
cam.position = CGPoint(x: 0.5, y: 0.5)
}
var previousTranslateX:CGFloat = 0.0
func panned (sender:UIPanGestureRecognizer) {
let currentTranslateX = sender.translation(in: view!).x
//calculate translation since last measurement
let translateX = currentTranslateX - previousTranslateX
let xMargin = (map.nodeSize.width - self.frame.width)/2
var newCamPosition = CGPoint(x: cam.position.x, y: cam.position.y)
let newPositionX = cam.position.x*self.frame.width + translateX
// since the camera x is 320, our limits are 140 and 460 ?
if newPositionX > self.frame.width/2 - xMargin && newPositionX < self.frame.width - xMargin {
newCamPosition.x = newPositionX/self.frame.width
}
centerCameraOnPoint(point: newCamPosition)
//(re-)set previous measurement
if sender.state == .ended {
previousTranslateX = 0
} else {
previousTranslateX = currentTranslateX
}
}
func centerCameraOnPoint(point: CGPoint) {
if cam != nil {
cam.position = point
}
}
Your camera is actually at a pixel point 0.5 points to the right of the centre, and 0.5 points up from the centre. At (0, 0) your camera is dead centre of the screen.
I think the mistake you've made is a conceptual one, thinking that anchor point of the scene (0.5, 0.5) is the same as the centre coordinates of the scene.
If you're working in pixels, which it seems you are, then a camera position of (500, 700) will be at the top right of your map, ( -500, -700 ) will be at the bottom left.
This assumes you're using the midpoint anchor that comes default with the Xcode SpriteKit template.
Which means the answer to your question is: Literally move the camera as you please, around your map, since you'll now be confident in the knowledge it's pixel literal.
With one caveat...
a lot of games use constraints to stop the camera somewhat before it gets to the edge of a map so that the map isn't half off and half on the screen. In this way the map's edge is showing, but the furthest the camera travels is only enough to reveal that edge of the map. This becomes a constraints based effort when you have a player/character that can walk/move to the edge, but the camera doesn't go all the way out there.

Custom Particle System for iOS

I want to create a particle system on iOS using sprite kit where I define the colour of each individual particle. As far as I can tell this isn't possible with the existing SKEmitterNode.
It seems that best I can do is specify general behaviour. Is there any way I can specify the starting colour and position of each particle?
This can give you a basic idea what I was meant in my comments. But keep in mind that it is untested and I am not sure how it will behave if frame rate drops occur.
This example creates 5 particles per second, add them sequentially (in counterclockwise direction) along the perimeter of a given circle. Each particle will have different predefined color. You can play with Settings struct properties to change the particle spawning speed or to increase or decrease number of particles to emit.
Pretty much everything is commented, so I guess you will be fine:
Swift 2
import SpriteKit
struct Settings {
static var numberOfParticles = 30
static var particleBirthRate:CGFloat = 5 //Means 5 particles per second, 0.2 means one particle in 5 seconds etc.
}
class GameScene: SKScene {
var positions = [CGPoint]()
var colors = [SKColor]()
var emitterNode:SKEmitterNode?
var currentPosition = 0
override func didMoveToView(view: SKView) {
backgroundColor = .blackColor()
emitterNode = SKEmitterNode(fileNamed: "rain.sks")
if let emitter = emitterNode {
emitter.position = CGPoint(x: CGRectGetMidX(frame), y: CGRectGetMidY(frame))
emitter.particleBirthRate = Settings.particleBirthRate
addChild(emitter)
let radius = 50.0
let center = CGPointZero
for var i = 0; i <= Settings.numberOfParticles; i++ {
//Randomize color
colors.append(SKColor(red: 0.78, green: CGFloat(i*8)/255.0, blue: 0.38, alpha: 1))
//Create some points on a perimeter of a given circle (radius = 40)
let angle = Double(i) * 2.0 * M_PI / Double(Settings.numberOfParticles)
let x = radius * cos(angle)
let y = radius * sin(angle)
let currentParticlePosition = CGPointMake(CGFloat(x) + center.x, CGFloat(y) + center.y)
positions.append(currentParticlePosition)
if i == 1 {
/*
Set start position for the first particle.
particlePosition is starting position for each particle in the emitter's coordinate space. Defaults to (0.0, 0,0).
*/
emitter.particlePosition = positions[0]
emitter.particleColor = colors[0]
self.currentPosition++
}
}
// Added just for debugging purposes to show positions for every particle.
for particlePosition in positions {
let sprite = SKSpriteNode(color: SKColor.orangeColor(), size: CGSize(width: 1, height: 1))
sprite.position = convertPoint(particlePosition, fromNode:emitter)
sprite.zPosition = 2
addChild(sprite)
}
let block = SKAction.runBlock({
// Prevent strong reference cycles.
[unowned self] in
if self.currentPosition < self.positions.count {
// Set color for the next particle
emitter.particleColor = self.colors[self.currentPosition]
// Set position for the next particle. Keep in mind that particlePosition is a point in the emitter's coordinate space.
emitter.particlePosition = self.positions[self.currentPosition++]
}else {
//Stop the action
self.removeActionForKey("emitting")
emitter.particleBirthRate = 0
}
})
// particleBirthRate is a rate at which new particles are generated, in particles per second. Defaults to 0.0.
let rate = NSTimeInterval(CGFloat(1.0) / Settings.particleBirthRate)
let sequence = SKAction.sequence([SKAction.waitForDuration(rate), block])
let repeatAction = SKAction.repeatActionForever(sequence)
runAction(repeatAction, withKey: "emitting")
}
}
}
Swift 3.1
import SpriteKit
struct Settings {
static var numberOfParticles = 30
static var particleBirthRate:CGFloat = 5 //Means 5 particles per second, 0.2 means one particle in 5 seconds etc.
}
class GameScene: SKScene {
var positions = [CGPoint]()
var colors = [SKColor]()
var emitterNode: SKEmitterNode?
var currentPosition = 0
override func didMove(to view: SKView) {
backgroundColor = SKColor.black
emitterNode = SKEmitterNode(fileNamed: "rain.sks")
if let emitter = emitterNode {
emitter.position = CGPoint(x: frame.midX, y: frame.midY)
emitter.particleBirthRate = Settings.particleBirthRate
addChild(emitter)
let radius = 50.0
let center = CGPoint.zero
for var i in 0...Settings.numberOfParticles {
//Randomize color
colors.append(SKColor(red: 0.78, green: CGFloat(i * 8) / 255.0, blue: 0.38, alpha: 1))
//Create some points on a perimeter of a given circle (radius = 40)
let angle = Double(i) * 2.0 * Double.pi / Double(Settings.numberOfParticles)
let x = radius * cos(angle)
let y = radius * sin(angle)
let currentParticlePosition = CGPoint.init(x: CGFloat(x) + center.x, y: CGFloat(y) + center.y)
positions.append(currentParticlePosition)
if i == 1 {
/*
Set start position for the first particle.
particlePosition is starting position for each particle in the emitter's coordinate space. Defaults to (0.0, 0,0).
*/
emitter.particlePosition = positions[0]
emitter.particleColor = colors[0]
self.currentPosition += 1
}
}
// Added just for debugging purposes to show positions for every particle.
for particlePosition in positions {
let sprite = SKSpriteNode(color: SKColor.orange, size: CGSize(width: 1, height: 1))
sprite.position = convert(particlePosition, from: emitter)
sprite.zPosition = 2
addChild(sprite)
}
let block = SKAction.run({
// Prevent strong reference cycles.
[unowned self] in
if self.currentPosition < self.positions.count {
// Set color for the next particle
emitter.particleColor = self.colors[self.currentPosition]
// Set position for the next particle. Keep in mind that particlePosition is a point in the emitter's coordinate space.
emitter.particlePosition = self.positions[self.currentPosition]
self.currentPosition += 1
} else {
//Stop the action
self.removeAction(forKey: "emitting")
emitter.particleBirthRate = 0
}
})
// particleBirthRate is a rate at which new particles are generated, in particles per second. Defaults to 0.0.
let rate = TimeInterval(CGFloat(1.0) / Settings.particleBirthRate)
let sequence = SKAction.sequence([SKAction.wait(forDuration: rate), block])
let repeatAction = SKAction.repeatForever(sequence)
run(repeatAction, withKey: "emitting")
}
}
}
Orange dots are added just for debugging purposes and you can remove that part if you like.
Personally I would say that you are overthinking this, but I might be wrong because there is no clear description of what you are trying to make and how to use it. Keep in mind that SpriteKit can render a bunch of sprites in a single draw call in very performant way. Same goes with SKEmitterNode if used sparingly. Also, don't underestimate SKEmitterNode... It is very configurable actually.
Here is the setup of Particle Emitter Editor:
Anyways, here is the final result:
Note that nodes count comes from an orange SKSpriteNodes used for debugging. If you remove them, you will see that there is only one node added to the scene (emitter node).
What you want is completely possible, probably even in real time. Unfortunately to do such a thing the way you describe with moving particles as being a particle for each pixel would be best done with a pixel shader. I don't know of a clean method that would allow you to draw on top of the scene with a pixel shader otherwise all you would need is a pixel shader that takes the pixels and moves them out from the center. I personally wouldn't try to do this unless I built the game with my own custom game engine in place of spritekit.
That being said I'm not sure a pixel per pixel diffusion is the best thing in most cases. Expecially if you have cartoony art. Many popular games will actually make sprites for fragments of the object they expect to shader. So like if it's an airplane you might have a sprite for the wings with perhaps even wires hanging out of this. Then when it is time to shatter the plane, remove it from the scene and replace the area with the pieces in the same shape of the plane... Sorta like a puzzle. This will likely take some tweaking. Then you can add skphysicsbodies to all of these pieces and have a force push them out in all directions. Also this doesn't mean that each pixel gets a node. I would suggest creatively breaking it into under 10 pieces.
And as whirlwind said you could all ways get things looking "like" it actually disintegrated by using an emitter node. Just make the spawn area bigger and try to emulate the color as much as possible. To make the ship dissappear you could do a fade perhaps? Or Mabye an explosion sprite over it? Often with real time special effects and physics, or with vfx it is more about making it look like reality then actually simulating reality. Sometimes you have to use trickery to get things to look good and run real-time.
If you want to see how this might look I would recommend looking at games like jetpac joyride.
Good luck!

checking to see if location in scene is occupied by sprite

I am building my first iPhone game using Xcode, SpriteKit and Swift. I am new to these technologies but I am familiar with general programming concepts.
Here is what I am trying to do in English. I want circles to randomly appear on the screen and then begin to expand in size. However, I do not want a circle to appear in a location where a circle currently exists. I am having trouble determining each circle's position.
Inside GameScene.swift I have the following code inside the didMoveToView:
runAction(SKAction.repeatActionForever(
SKAction.sequence([
SKAction.runBlock(addCircle), SKAction.waitForDuration(3, withRange: 2)]
)))
The piece of code above calls my "addCircle" method:
func addCircle() {
// Create sprite.
let circle = SKSpriteNode(imageNamed: "grad640x640_circle")
circle.name = "circle"
circle.xScale = 0.1
circle.yScale = 0.1
// Determine where to position the circle.
let posX = random(min: 50, max: 270)
let posY = random(min: 50, max: 518)
// ***Check to see if position is currently occupied by another circle here.
circle.position = CGPoint(x: posX, y: posY)
// Add circle to the scene.
addChild(circle)
// Expand the circle.
let expand = SKAction.scaleBy(2, duration: 0.5)
circle.runAction(expand)
}
The random function above just chooses a random number within the given range. How can I check to see if my random functions are generating a location that is currently occupied by another circle?
I was thinking of using a do..while loop to randomly generate a set of x and y coordinates and then check to see if a circle is at that location but I cannot find how to check for that condition. Any help would be greatly appreciated.
There are a few methods which can help you in this regard:
(BOOL) intersectsNode: (SKNode*)node, available with SKNode, and
CGRectContainsPoint() as well as the CGRectContainsRect() methods.
For instance the loop to check for intersection can look as follows:
var point: CGPoint
var exit:Bool = false
while (!exit) {
let posX = random(min: 50, max: 270)
let posY = random(min: 50, max: 518)
point = CGPoint(x: posX, y: posY)
var pointFound: Bool = true
self.enumerateChildNodesWithName("circle", usingBlock: {
node, stop in
let sprite:SKSpriteNode = node as SKSpriteNode
if (CGRectContainsPoint(sprite.frame, point))
{
pointFound = false
stop.memory = true
}
})
if (pointFound)
{
exit = true
}
}
//point contains CGPoint where no other circle exists
//Declare new circle at point

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