I am creating a iOS Game where a player has a bow and arrow that spins in a 360 degree circle, and the player must shoot the bow at the right time to hit the target. Right now I am having trouble getting the arrow to shoot in the direction the bow is facing, as well as getting the arrow to shoot at the right angle towards that direction.
let bullet = SKSpriteNode(fileNamed: "Bullet")
bullet?.size = CGSize(width: 100, height: 100)
bullet.zPosition = -5
bullet.position = CGPointMake(player.position.x, player.position.y)
bullet.zRotation = player.zRotation
let action = SKAction.moveToY(self.size.height + 30, duration: 0.8)
let actionDone = SKAction.removeFromParent()
bullet.runAction(SKAction.sequence([action, actionDone]))
bullet.physicsBody = SKPhysicsBody(rectangleOfSize: bullet.size)
bullet.physicsBody?.affectedByGravity = false
bullet.physicsBody?.dynamic = false
self.addChild(bullet)
The player refers the the bow for reference.
Instead of moving the bullet to self.size.height + 30 in the Y direction and 0 pixels in the X direction, you can rotate that movement direction by the zRotation using trigonometry.
let amount = self.size.height + 30
let action = SKAction.moveTo(CGPointMake(bullet.position.x + amount * sin(bullet.zRotation), bullet.position.y + amount * cos(bullet.zRotation)), duration: 0.8)
You can get the behavior you are looking for by calculating a force vector from the bullet's zRotation and then use it to apply a force to the bullet's physicsBody.
To do this we will use trigonometry.
//adjust rotation by pi/2 radians to match spriteKits rotation system
let adjustedRotation = bullet.zRotation + .pi/2
//intensity scalar
let intensity:CGFloat = 4000 //adjust this value
//find x and y components using adjustedRotation and scale by intensity
let vx = intensity * cos(adjustedRotation)
let vy = intensity * sin(adjustedRotation)
//make vector using vx and vy components
let forceVector = CGVector(dx:vx, dy: vy)
//apply force to physicsBody
bullet.physicsBody?.applyForce(forceVector)
my question was
I want to create a simple line graph with certain values. This is done in a view within the mainviewcontroller. I created a UIview named chart. I pass the data to the chart when its retrieved from the API. I figured out how to draw the axis but I am stuck now. I cant find anything on google on how to set labels on intervals and to make the points appear dynamically.
draw the xasis and its labels.
draw the dots in the graph.
My salution
i figured out how to do all the things i asked for.
The code I have now:
class ChartView: UIView {
//some variables
var times: [String] = []
var AmountOfRain: [Double] = []
let pathy = UIBezierPath()
let pathx = UIBezierPath()
var beginwitharray = Array<CGFloat>()
// Only override draw() if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
override func draw(_ rect: CGRect) {
// Drawing code
//draw the y line
pathy.move(to: CGPoint(x: 30, y: 10))
pathy.addLine(to: CGPoint(x: 30, y: 10))
pathy.addLine(to: CGPoint(x: 30, y: frame.size.height - 30))
UIColor.black.setStroke()
pathy.lineWidth = 1.0
pathy.stroke()
//draw the x line
pathx.move(to: CGPoint(x: 30, y: frame.size.height - 30))
pathx.addLine(to: CGPoint(x: 30, y: frame.size.height - 30))
pathx.addLine(to: CGPoint(x: frame.size.width - 30, y: frame.size.height - 30))
UIColor.black.setStroke()
pathx.lineWidth = 1.0
pathx.stroke()
//when the data arrives form the SUPER slow duienradar API refresh it with the data
if beginwitharray != []{
//remove the label retriving data
let label = viewWithTag(1)
DispatchQueue.main.sync {
label?.removeFromSuperview()
}
//create the dots in the graph
var point = CGPoint()
//simple way to do 2 loop in 1 loop.
var intforbeginarray = 0
let stoke = UIBezierPath()
//get the first 6 itmes out of the rain array cuz of space issues
let first6aumountarray = AmountOfRain[0...5]
stoke.move(to: CGPoint(x: 30, y: self.frame.size.height - 30))
//loop trough the data in the amounts array
for amount in first6aumountarray{
//determen the hight of the dot
let InitialHeight = (CGFloat(amount) * (self.frame.size.height - 30))/6
let pointHeight = (frame.size.height - 30) - InitialHeight
//make the point so we can draw it using UIbezierpath()
point = CGPoint(x: beginwitharray[intforbeginarray] + 20, y: pointHeight)
intforbeginarray += 1
//create the dot
let dot = UIBezierPath()
dot.addArc(withCenter: point, radius: CGFloat(5), startAngle: CGFloat(0), endAngle: CGFloat(360), clockwise: true)
UIColor.black.setFill()
dot.lineWidth = 30
dot.fill()
//create the line between dots will give a warning on the last one cuz the last one doenst go anyway
stoke.addLine(to: point)
stoke.move(to: point)
stoke.lineWidth = 1
UIColor.black.setStroke()
}
//make the strokes
stoke.stroke()
}
}
func getvalues(RainData: [Double], TimesData:[String]){
//assing the data to the subview
self.AmountOfRain = RainData
self.times = TimesData
//xaxis values
let maxint = [0, 1, 2, 3, 4, 5, 6]
//calculate the hight spacing to fit the graph
let heightperstep = ((self.frame.size.height - 5)/6)-5
var beginheight = self.frame.size.height - 35
//calculate the width spacing to fit the graph
let widthperstep = ((self.frame.size.width - 5)/6)-5
var beginwith = CGFloat(30)
//extra check to see if we have data at all.
if times != []{
//get the first 6 items out of the times array for use in our graph
let first6 = times[0...5]
//draw the label on the main queue
DispatchQueue.main.sync {
//draw the xaxis labels accroding to the spacing
for number in maxint{
let label = UILabel(frame: CGRect(x: 5, y: beginheight, width: 25, height: 15))
label.text = "\(number)"
self.addSubview(label)
beginheight = beginheight - heightperstep
}
//draw the yaxis labels according to the spacing
for time in first6{
let label = UILabel(frame: CGRect(x: beginwith, y: self.frame.size.height - 20, width: 55, height: 15))
label.text = time
self.addSubview(label)
beginwitharray.append(beginwith)
beginwith = beginwith + widthperstep
}
}
}
//redrawthe graph with new data.
setNeedsDisplay()
}}
Any help would be appreciated. I also can't use a lib or a pod since this is a school project and I need to create a simple graph.
EDIT:
Completed my code, cleared up an error when running this code
What I did first was to draw the x-asis and the y-axis. After this I considered reasonable values for the aumountofrain data. this turns out cannot really be higher then 6. Since I could fit around 6 labels in the space I have the steps where easy go down by 1 till I hit 0. The calculations I did are for my specific frame height. After I figured it all out and the padding for the y-asxis. It was a matter of figuring out how to get the dots in the right place. Since I already have the data in the beginwitharray I just needed to calculate the height. Then it was simply loop trough the data and draw each dot. Then I just had to connect the dots using the uibezierpath.
i hope my troubles will save someone a lot of time when they read how i done it.
This might be helpful: Draw Graph curves with UIBezierPath
Essentially what you need to do is for every data set you have you need to know the y-axis range of values and based on those ranges assign each value a CGFloat value (in your case inches of rain needs to correlate to a certain CGFloat value). Let's say you have your set amountOfRain = [0.1, 1.3, 1.5, 0.9, 0.1, 0] so your range is var rangeY = amountOfRain.max() - amountOfRain.min(). now lets find out where your first data point 0.1 should go on your graph by converting inches of rain to a CGFloat value that corresponds to the axis you've drawn already, this equation is just basic algebra: let y1 = (amountOfRain[0]/rangeY)*((frame.size.height-30) - 10) + 10 now it looks like your rain samples are at regular intervals so maybe let x1:CGFloat = 10 now you can add a dot or something at the CGPoint corresponding with (x1,y1). If you did this with all the data points it would create a graph that has your maximum value at the top of the graph and minimum value at the bottom. Good Luck!
Hey I have a ball that gets moved by a force-applied. What im trying to get it to do is basically have the causal effect of gravity acting upon it while its moving through the air to its destination. basically when the "move to" action is playing gravity does not take affect so instead of slowly falling down to the ground it instead moves to its final position then it just falls straight down when the "move to" action stops. do to the gravity in the scene.
Im trying to get the ball to be thrown in an arc and land on the target?
Code:
func CreateBall() {
let BallScene = SCNScene(named: "art.scnassets/Footballs.dae")
Ball = BallScene!.rootNode.childNodeWithName("Armature", recursively: true)! //the Amature/Bones
Ballbody = BallScene!.rootNode.childNodeWithName("Ball", recursively: true)!
let collisionCapsuleRadius3 = CGFloat(0.01) // Width of physicsBody
let collisionCapsuleHeight3 = CGFloat(0.01) // Height of physicsBody
Ball.position = SCNVector3Make(Guy.position.x, Guy.position.y, Guy.position.z)
Ball.scale = SCNVector3Make(5, 5, 5)
Ball.rotation = SCNVector4Make(0.0,0.0,0.0,0.0) // x,y,z,w
Ball.physicsBody = SCNPhysicsBody(type: .Dynamic, shape:SCNPhysicsShape(geometry: SCNCapsule(capRadius: collisionCapsuleRadius3, height: collisionCapsuleHeight3), options:nil))
Ball.physicsBody?.affectedByGravity = true
Ball.physicsBody?.friction = 1 //
Ball.physicsBody?.restitution = 0 //bounceness of the object. 1.0 will boounce forever
Ball.physicsBody?.angularDamping = 1 // ability to rotate
Ball.physicsBody?.mass = 1
Ball.physicsBody?.rollingFriction = 1
Ball.physicsBody!.categoryBitMask = BitmaskCollision4
Ball.physicsBody?.contactTestBitMask = BitmaskCollision3 //| BitmaskCollision2
Ballbody.physicsBody?.collisionBitMask = BitmaskCollision2 | BitmaskCollision3 | BitmaskCollision//| BitmaskCollision2
scnView.scene!.rootNode.addChildNode(Ball)
scnView.scene!.rootNode.addChildNode(Ballbody)
}
CreateBall()
now this is where the magic happens:
scnView.scene!.physicsWorld.gravity = SCNVector3(x: 0, y: -9.8, z: 0)
let location = SCNVector3(Guy2.presentationNode.position.x, 0.0, Guy2.presentationNode.position.z + Float(50) )
let moveAction = SCNAction.moveTo(location, duration: 2.0)
Ball.runAction(SCNAction.sequence([moveAction]))
let forceApplyed = SCNVector3(x: 0.0, y: 100.0 , z: 0.0)
Ball.physicsBody?.applyForce(forceApplyed, atPosition: Ball.presentationNode.position, impulse: true)
Combining SCNActions and physics doesn't work, you need to use one or the other. Using physics you can calculate the exact force needed to propel your node to a target.
I have adapted a solution for Unity found here and utilised an SCNVector3 extension that makes some of the calculations much easier.
Basically you pass in an SCNNode that you want to throw, an SCNVector3 for the target and an angle (in radians) that you want the node to be thrown at. This function will then work out the force required to reach the target.
func shootProjectile() {
let velocity = ballisticVelocity(ball, target: target.position, angle: Float(0.4))
ball.physicsBody?.applyForce(velocity, impulse: true)
}
func ballisticVelocity(projectile:SCNNode, target: SCNVector3, angle: Float) -> SCNVector3 {
let origin = projectile.presentationNode.position
var dir = target - origin // get target direction
let h = dir.y // get height difference
dir.y = 0 // retain only the horizontal direction
var dist = dir.length() // get horizontal distance
dir.y = dist * tan(angle) // set dir to the elevation angle
dist += h / tan(angle) // correct for small height differences
// calculate the velocity magnitude
let vel = sqrt(dist * -scene.physicsWorld.gravity.y / sin(2 * angle))
return dir.normalized() * vel * Float(projectile.physicsBody!.mass)
}
It is also important to set the damping of the physicsBody to 0, otherwise it will be affected by air resistance.
I’m not going to pretend to know exactly how this works, but Wikipedia has articles that explain all the maths behind it.
UPDATE
Since using the code above I've noticed it doesn't always work, especially when the heights of the origin and target are different. From the same forum this function seems more reliable.
func calculateBestThrowSpeed(origin: SCNVector3, target: SCNVector3, timeToTarget:Float) -> SCNVector3 {
let gravity:SCNVector3 = sceneView.scene!.physicsWorld.gravity
let toTarget = target - origin
var toTargetXZ = toTarget
toTargetXZ.y = 0
let y = toTarget.y
let xz = toTargetXZ.length()
let t = timeToTarget
let v0y = y / t + 0.5 * gravity.length() * t
let v0xz = xz / t
var result = toTargetXZ.normalized()
result *= v0xz
result.y = v0y
return result
}
I've been trying to draw a cylinder between two points on the outer edge of a sphere using SceneKit. I have already produced a line between these two points using primitive geometry and openGL with SCNRendering Delegate, but now I need to produce a cylinder between these two (well, not just two, but any two 3D vectors that sit on the surface of the sphere). I've been working on this for about 3 days straight now, and I've gone through everything I could find on implementing Quaternions to make this happen, but as it stands, I can't get it to work. Academic articles, scientific studies, and nothing, nothing is working to realign a cylinder between two fixed points. I need an algorithm to do this.
Anyway, here's my most recent code that doesn't work, but this is just a small snippet of nearly 2k lines of code I've worked through so far without the intended result. I know I can move to something more advanced like building my own SCNProgram and/or SCNRenderer to then access GLSL, OpenGL, and Metal complexity, but this seems like something that should be possible using Scenekit and converting between GLKit vector structs to and from SCNVector structs, but so far it's impossible:
Code:
The following code ingests Longitude and Latitude coordinates and projects them onto the surface of a 3D sphere. These coordinates are returned through a proprietary function I build where I received a SCNVector3 of {x,y,z} coordinates that display accurately on my 3D sphere. I draw a line between two sets of Longitude and Latitude coordinates where the lines that are drawn using primitives shoot through the center of the sphere. So, as I mentioned above, I want this same functionality but with cylinders, not lines (by the way, the longitude and latitude coordinates listed here are bogus, they are randomly generated but both fall on the Earth's surface).
drawLine = [self lat1:37.76830 lon1:-30.40096 height1:tall lat2:3.97620 lon2:63.73095 height2:tall];
float cylHeight = GLKVector3Distance(SCNVector3ToGLKVector3(cooridnateSetOne.position), SCNVector3ToGLKVector3(coordinateSetTwo.position));
SCNCylinder * cylTest = [SCNCylinder cylinderWithRadius:0.2 height:cylHeight];
SCNNode * test = [SCNNode nodeWithGeometry:cylTest];
SCNMaterial *material = [SCNMaterial material];
[[material diffuse] setContents:[SKColor whiteColor]];
material.diffuse.intensity = 60;
material.emission.contents = [SKColor whiteColor];
material.lightingModelName = SCNLightingModelConstant;
[cylTest setMaterials:#[material]];
GLKVector3 u = SCNVector3ToGLKVector3(cooridnateSetOne.position);
GLKVector3 v = SCNVector3ToGLKVector3(cooridnateSetTwo.position);
GLKVector3 w = GLKVector3CrossProduct(u, v);
GLKQuaternion q = GLKQuaternionMakeWithAngleAndVector3Axis(GLKVector3DotProduct(u,v), GLKVector3Normalize(w));
q.w += GLKQuaternionLength(q);
q = GLKQuaternionNormalize(q);
SCNVector4 final = SCNVector4FromGLKVector4(GLKVector4Make(q.x, q.y, q.z, q.w));
test.orientation = final;
Other code I've tried includes this same sort of method, in fact, I even built my own SCNVector3 and SCNVector4 Math libraries in Objective-C to see if my math methods produced different values than using GLKit maths, but I get the same results with both methods. Any help would be awesome, but for now, I'm not looking to jump into anything more complicated than SceneKit. I won't be diving into Metal and/or OpenGL for another month or two. Thanks!
EDIT:
The variables "cooridnateSetOne" and "cooridnateSetTwo" are SCNNodes that are produced by another function that forces a primitive line geometry into this node and then returns it to a subclass implementation of SCNScene.
Here's a quick demo using node hierarchy (to get the cylinder situated such that its end is at one point and its length is along the local z-axis) and a constraint (to make that z-axis look at another point).
let root = view.scene!.rootNode
// visualize a sphere
let sphere = SCNSphere(radius: 1)
sphere.firstMaterial?.transparency = 0.5
let sphereNode = SCNNode(geometry: sphere)
root.addChildNode(sphereNode)
// some dummy points opposite each other on the sphere
let rootOneThird = CGFloat(sqrt(1/3.0))
let p1 = SCNVector3(x: rootOneThird, y: rootOneThird, z: rootOneThird)
let p2 = SCNVector3(x: -rootOneThird, y: -rootOneThird, z: -rootOneThird)
// height of the cylinder should be the distance between points
let height = CGFloat(GLKVector3Distance(SCNVector3ToGLKVector3(p1), SCNVector3ToGLKVector3(p2)))
// add a container node for the cylinder to make its height run along the z axis
let zAlignNode = SCNNode()
zAlignNode.eulerAngles.x = CGFloat(M_PI_2)
// and position the zylinder so that one end is at the local origin
let cylinder = SCNNode(geometry: SCNCylinder(radius: 0.1, height: height))
cylinder.position.y = -height/2
zAlignNode.addChildNode(cylinder)
// put the container node in a positioning node at one of the points
p2Node.addChildNode(zAlignNode)
// and constrain the positioning node to face toward the other point
p2Node.constraints = [ SCNLookAtConstraint(target: p1Node) ]
Sorry if you were looking for an ObjC-specific solution, but it was quicker for me to prototype this in an OS X Swift playground. (Also, less CGFloat conversion is needed in iOS, because the element type of SCNVector3 is just Float there.)
Just for reference a more elegant SCNCyclinder implementation to connect a start and end position with a given radius:
func makeCylinder(from: SCNVector3, to: SCNVector3, radius: CGFloat) -> SCNNode
{
let lookAt = to - from
let height = lookAt.length()
let y = lookAt.normalized()
let up = lookAt.cross(vector: to).normalized()
let x = y.cross(vector: up).normalized()
let z = x.cross(vector: y).normalized()
let transform = SCNMatrix4(x: x, y: y, z: z, w: from)
let geometry = SCNCylinder(radius: radius,
height: CGFloat(height))
let childNode = SCNNode(geometry: geometry)
childNode.transform = SCNMatrix4MakeTranslation(0.0, height / 2.0, 0.0) *
transform
return childNode
}
Needs the following extension:
extension SCNVector3 {
/**
* Calculates the cross product between two SCNVector3.
*/
func cross(vector: SCNVector3) -> SCNVector3 {
return SCNVector3Make(y * vector.z - z * vector.y, z * vector.x - x * vector.z, x * vector.y - y * vector.x)
}
func length() -> Float {
return sqrtf(x*x + y*y + z*z)
}
/**
* Normalizes the vector described by the SCNVector3 to length 1.0 and returns
* the result as a new SCNVector3.
*/
func normalized() -> SCNVector3 {
return self / length()
}
}
extension SCNMatrix4 {
public init(x: SCNVector3, y: SCNVector3, z: SCNVector3, w: SCNVector3) {
self.init(
m11: x.x,
m12: x.y,
m13: x.z,
m14: 0.0,
m21: y.x,
m22: y.y,
m23: y.z,
m24: 0.0,
m31: z.x,
m32: z.y,
m33: z.z,
m34: 0.0,
m41: w.x,
m42: w.y,
m43: w.z,
m44: 1.0)
}
}
/**
* Divides the x, y and z fields of a SCNVector3 by the same scalar value and
* returns the result as a new SCNVector3.
*/
func / (vector: SCNVector3, scalar: Float) -> SCNVector3 {
return SCNVector3Make(vector.x / scalar, vector.y / scalar, vector.z / scalar)
}
func * (left: SCNMatrix4, right: SCNMatrix4) -> SCNMatrix4 {
return SCNMatrix4Mult(left, right)
}
Thank you, Rickster! I have taken it a little further and made a class out of it:
class LineNode: SCNNode
{
init( parent: SCNNode, // because this node has not yet been assigned to a parent.
v1: SCNVector3, // where line starts
v2: SCNVector3, // where line ends
radius: CGFloat, // line thicknes
radSegmentCount: Int, // number of sides of the line
material: [SCNMaterial] ) // any material.
{
super.init()
let height = v1.distance(v2)
position = v1
let ndV2 = SCNNode()
ndV2.position = v2
parent.addChildNode(ndV2)
let ndZAlign = SCNNode()
ndZAlign.eulerAngles.x = Float(M_PI_2)
let cylgeo = SCNCylinder(radius: radius, height: CGFloat(height))
cylgeo.radialSegmentCount = radSegmentCount
cylgeo.materials = material
let ndCylinder = SCNNode(geometry: cylgeo )
ndCylinder.position.y = -height/2
ndZAlign.addChildNode(ndCylinder)
addChildNode(ndZAlign)
constraints = [SCNLookAtConstraint(target: ndV2)]
}
override init() {
super.init()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
}
I have tested this class successfully in an iOS app, using this function,
which draws 100 lines (oops cylinders :o).
func linesTest3()
{
let mat = SCNMaterial()
mat.diffuse.contents = UIColor.whiteColor()
mat.specular.contents = UIColor.whiteColor()
for _ in 1...100 // draw 100 lines (as cylinders) between random points.
{
let v1 = SCNVector3( x: Float.random(min: -50, max: 50),
y: Float.random(min: -50, max: 50),
z: Float.random(min: -50, max: 50) )
let v2 = SCNVector3( x: Float.random(min: -50, max: 50),
y: Float.random(min: -50, max: 50),
z: Float.random(min: -50, max: 50) )
// Just for testing, add two little spheres to check if lines are drawn correctly:
// each line should run exactly from a green sphere to a red one:
root.addChildNode(makeSphere(v1, radius: 0.5, color: UIColor.greenColor()))
root.addChildNode(makeSphere(v2, radius: 0.5, color: UIColor.redColor()))
// Have to pass the parentnode because
// it is not known during class instantiation of LineNode.
let ndLine = LineNode(
parent: scene.rootNode, // ** needed
v1: v1, // line (cylinder) starts here
v2: v2, // line ends here
radius: 0.2, // line thickness
radSegmentCount: 6, // hexagon tube
material: [mat] ) // any material
root.addChildNode(ndLine)
}
}
Regards. (btw. I can only see 3D objects.. I have never seen a "line" in my life :o)
i use SCNVector3 extensions with:
func cylVector(from : SCNVector3, to : SCNVector3) -> SCNNode {
let vector = to - from,
length = vector.length()
let cylinder = SCNCylinder(radius: cylsRadius, height: CGFloat(length))
cylinder.radialSegmentCount = 6
cylinder.firstMaterial = material
let node = SCNNode(geometry: cylinder)
node.position = (to + from) / 2
node.eulerAngles = SCNVector3Make(CGFloat(Double.pi/2), acos((to.z-from.z)/length), atan2((to.y-from.y), (to.x-from.x) ))
return node
}
Here's an entire method using Objective-C
First, here's how you use it:
SCNNode * testNode = [self lat1:-35 lon1:108 height1:tall lat2:-35 lon2:30 height2:0];
Inputs:
1rst location
lat1 = latitude of 1rst location
lon1 = longitude of 1rst location
height1 = distance from earth for 1rst location
lat2 = latitude of 2nd location
lon2 = latitude of 2nd location
height2 = distance from earth for 2nd location
The second method creates the SCNVector3 points for each location in question above:
-(SCNNode *)lat1:(double)lat1 lon1:(double)lon1 height1:(float)height1 lat2:(double)lat2 lon2:(double)lon2 height2:(float)height2 {
SCNVector3 positions[] = {[self lat:lat1 lon:lon1 height:height1], [self lat:lat2 lon:lon2 height:height2]};
float cylHeight = GLKVector3Distance(SCNVector3ToGLKVector3(positions[0]), SCNVector3ToGLKVector3(positions[1]))/4;
SCNCylinder * masterCylinderNode = [SCNCylinder cylinderWithRadius:0.05 height:cylHeight];
SCNMaterial *material = [SCNMaterial material];
[[material diffuse] setContents:[SKColor whiteColor]];
material.lightingModelName = SCNLightingModelConstant;
material.emission.contents = [SKColor whiteColor];
[masterCylinderNode setMaterials:#[material]];
SCNNode *mainLocationPointNodeTestA = [mainLocationPointNode clone];
SCNNode *mainLocationPointNodeTestB = [mainLocationPointNode clone];
mainLocationPointNodeTestA.position = positions[0];
mainLocationPointNodeTestB.position = positions[1];
SCNNode * mainParentNode = [SCNNode node];
SCNNode * tempNode2 =[SCNNode nodeWithGeometry:masterCylinderNode];
[mainParentNode addChildNode:mainLocationPointNodeTestA];
[mainParentNode addChildNode:mainLocationPointNodeTestB];
[mainParentNode addChildNode:tempNode2];
[mainParentNode setName:#"parentToLineNode"];
tempNode2.position = SCNVector3Make((positions[0].x+positions[1].x)/2, (positions[0].y+positions[1].y)/2, (positions[0].z+positions[1].z)/2);
tempNode2.pivot = SCNMatrix4MakeTranslation(0, cylHeight*1.5, 0);
GLKVector3 normalizedVectorStartingPosition = GLKVector3Make(0.0, 1.0, 0.0);
GLKVector3 magicAxis = GLKVector3Normalize(GLKVector3Subtract(GLKVector3Make(positions[0].x/2, positions[0].y/2, positions[0].z/2), GLKVector3Make(positions[1].x/2, positions[1].y/2, positions[1].z/2)));
GLKVector3 rotationAxis = GLKVector3CrossProduct(normalizedVectorStartingPosition, magicAxis);
CGFloat rotationAngle = GLKVector3DotProduct(normalizedVectorStartingPosition, magicAxis);
GLKVector4 rotation = GLKVector4MakeWithVector3(rotationAxis, acos(rotationAngle));
tempNode2.rotation = SCNVector4FromGLKVector4(rotation);
return mainParentNode;
}
This second method uses hard coded numbers for earth's radius and curvature, I'm showing this just to show the numbers required for total 100% accuracy, this is how it works. You'll want to change this to the correct dimensions for your scene, obviously, but here's the method. This is an adaptation of methods used by Link. An explanation an be found here: Link. I put this together very quickly but it works and is accurate, feel free to change the number formats to your liking.
-(SCNVector3)lat:(double)lat lon:(double)lon height:(float)height {
double latd = 0.0174532925;
double latitude = latd*lat;
double longitude = latd*lon;
Float64 rad = (Float64)(6378137.0);
Float64 f = (Float64)(1.0/298.257223563);
double cosLat = cos(latitude);
double sinLat = sin(latitude);
double FF = pow((1.0-f), 2);
double C = 1/(sqrt(pow(cosLat,2) + FF * pow(sinLat,2)));
double S = C * FF;
double x = ((rad * C)*cosLat * cos(longitude))/(1000000/(1+height));
double y = ((rad * C)*cosLat * sin(longitude))/(1000000/(1+height));
double z = ((rad * S)*sinLat)/(1000000/(1+height));
return SCNVector3Make(y+globeNode.position.x, z+globeNode.position.y, x+globeNode.position.z);
}
I have been looking for a solution to make cylinder between two points and thanks to rickster, I have used his answer to make SCNNode extension. There, I have added missing conditions for a possible cylinder orientation to avoid its wrong opposite direction.
func makeCylinder(positionStart: SCNVector3, positionEnd: SCNVector3, radius: CGFloat , color: NSColor, transparency: CGFloat) -> SCNNode
{
let height = CGFloat(GLKVector3Distance(SCNVector3ToGLKVector3(positionStart), SCNVector3ToGLKVector3(positionEnd)))
let startNode = SCNNode()
let endNode = SCNNode()
startNode.position = positionStart
endNode.position = positionEnd
let zAxisNode = SCNNode()
zAxisNode.eulerAngles.x = CGFloat(M_PI_2)
let cylinderGeometry = SCNCylinder(radius: radius, height: height)
cylinderGeometry.firstMaterial?.diffuse.contents = color
let cylinder = SCNNode(geometry: cylinderGeometry)
cylinder.position.y = -height/2
zAxisNode.addChildNode(cylinder)
let returnNode = SCNNode()
if (positionStart.x > 0.0 && positionStart.y < 0.0 && positionStart.z < 0.0 && positionEnd.x > 0.0 && positionEnd.y < 0.0 && positionEnd.z > 0.0)
{
endNode.addChildNode(zAxisNode)
endNode.constraints = [ SCNLookAtConstraint(target: startNode) ]
returnNode.addChildNode(endNode)
}
else if (positionStart.x < 0.0 && positionStart.y < 0.0 && positionStart.z < 0.0 && positionEnd.x < 0.0 && positionEnd.y < 0.0 && positionEnd.z > 0.0)
{
endNode.addChildNode(zAxisNode)
endNode.constraints = [ SCNLookAtConstraint(target: startNode) ]
returnNode.addChildNode(endNode)
}
else if (positionStart.x < 0.0 && positionStart.y > 0.0 && positionStart.z < 0.0 && positionEnd.x < 0.0 && positionEnd.y > 0.0 && positionEnd.z > 0.0)
{
endNode.addChildNode(zAxisNode)
endNode.constraints = [ SCNLookAtConstraint(target: startNode) ]
returnNode.addChildNode(endNode)
}
else if (positionStart.x > 0.0 && positionStart.y > 0.0 && positionStart.z < 0.0 && positionEnd.x > 0.0 && positionEnd.y > 0.0 && positionEnd.z > 0.0)
{
endNode.addChildNode(zAxisNode)
endNode.constraints = [ SCNLookAtConstraint(target: startNode) ]
returnNode.addChildNode(endNode)
}
else
{
startNode.addChildNode(zAxisNode)
startNode.constraints = [ SCNLookAtConstraint(target: endNode) ]
returnNode.addChildNode(startNode)
}
return returnNode
}