CODEWITHSUNDEEP
iphoneswiftxcodescenekitscnnode
user2252471
user2252471

Reputation: 289

SceneKit Physics – Friction and Concave Polyhedrons

I am working on a cornhole game in Scene Kit and have encountered a bug with SCNPhysicsShape and SCNPhysicsBody friction. The board for the game is loaded through a .dae file and is set as a SCNPhysicsShapeTypeConcavePolyhedron. This allows the bean bag to fall through the hole however it seems to nullify the friction on the board. When the bean bag hits the board it slides right off despite have a friction value of 1.0 (the bean bag has a friction value of 1.0 as well). If I change the board to SCNPhysicsShapeTypeConvexHull then the friction works but the bean bag does not fall through the hole.

Here is my custom board initialization:

let geo = nodeWithFile("board.dae").geometry!

geo.materials = [SCNMaterial()] 
geo.firstMaterial!.diffuse.contents = "wood_texture.png"
geo.firstMaterial!.diffuse.wrapS = SCNWrapMode.Repeat
geo.firstMaterial!.diffuse.wrapT = SCNWrapMode.Repeat
geo.firstMaterial!.diffuse.mipFilter = SCNFilterMode.Linear

self.geometry = geo
self.position = position
self.rotation = SCNVector4Make(1, 0, 0, -CFloat(degreesToRadians(65.0)))

let shape = SCNPhysicsShape(geometry: geo, options: [SCNPhysicsShapeTypeKey: SCNPhysicsShapeTypeConcavePolyhedron])

self.physicsBody = SCNPhysicsBody(type: .Static, shape: shape)
self.physicsBody!.restitution = 0.0
self.physicsBody!.rollingFriction = 1.0
self.physicsBody!.friction = 1.0

And here is the custom initialization for the bean bag

let geo = SCNBox(width: 20.0, height: 4.0, length: 20.0, chamferRadius: 5.0)

self.geometry = geo
self.position = position
self.geometry!.firstMaterial!.diffuse.contents = UIColor.blueColor()

let shape = SCNPhysicsShape(geometry: geo, options: [SCNPhysicsShapeTypeKey: SCNPhysicsShapeTypeBoundingBox])

self.physicsBody = SCNPhysicsBody(type: .Dynamic, shape: shape)
self.physicsBody!.restitution = 0.0
self.physicsBody!.rollingFriction = 1.0
self.physicsBody!.friction = 1.0

These are both inside of init methods for classes that subclass SCNNode

My question is: how can I keep the board as a ConcavePolyhedron and have the friction work at the same time?

Upvotes: 3

Views: 764

Answers (1)

Antonio Ciolino
Antonio Ciolino

Reputation: 556

This might not be the best answer, but it would work. Redesign your board into multiple pieces, leaving a hole in the middle that is not part of a geometry.

Upvotes: 1

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