linearGravityField（）不影响场景SceneKit中的物理实体 [英] linearGravityField() is not affecting physics bodies in the scene SceneKit

问题描述

我正在尝试使用SCNPhysicsField.linearGravityField对象来仅影响场景中的特定对象。问题是，我似乎无法让它影响任何事情。以下是我在Swift中的代码示例：

I'm trying to use a SCNPhysicsField.linearGravityField object to affect only specific objects in my scene. The problem is, that I can't seem to get it to affect anything. Here's a sample of my code in Swift:

let downGravityCatagory = 1 << 0
let fieldDown = SCNPhysicsField.linearGravityField()
let fieldUp = SCNPhysicsField.linearGravityField()
let fieldNode = SCNNode()

let sceneView = view as! SCNView
sceneView.scene = scene
sceneView.scene!.physicsWorld.gravity = SCNVector3(x: 0, y: 0, z: 0)

fieldDown.categoryBitMask = downGravityCatagory
fieldDown.active = true
fieldDown.strength = 3
fieldNode.physicsField = fieldDown
scene.rootNode.addChildNode(fieldNode)

var dice = SCNNode()
//I then attach geometry here
dice.physicsBody = SCNPhysicsBody(type: SCNPhysicsBodyType.Dynamic, shape: SCNPhysicsShape(geometry: dice.geometry!, options: nil))
dice.physicsBody?.categoryBitMask = downGravityCatagory
scene.rootNode.addChildNode(dice)

Even虽然物理实体被分配了与重力场相同的catagoryBitMask，它们只是在零G中浮动，只受物理世界引力的影响。

Even though the Physics Bodies are assigned the same catagoryBitMask as the gravity field, they just float there in zero G, only affected by the physicsworld gravity.

推荐答案

在节点上设置downGravityCatagory位掩码：

Set the "downGravityCatagory" bit mask on the node:

dice.categoryBitMask = downGravityCatagory;

物理的categoryBitMask仅用于物理碰撞。

the physics's categoryBitMask is for physics collisions only.

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