SKSpitekit 节点之间未检测到冲突

Question

我正在建造一个迷宫，并为墙壁添加了一些 SKSpritekit 节点，并为玩家添加了一个点。但是，当点和墙壁发生碰撞时，不会检测到碰撞。我的代码如下：

import UIKit
import SpriteKit
import GameplayKit
import Foundation
import GameplayKit


class level1: SKScene, SKPhysicsContactDelegate {
    var entities = [GKEntity]()
    var graphs = [String : GKGraph]()
    var dot = SKSpriteNode()

override func sceneDidLoad () {
    buildMaze()
    addDot()

    func addDot() {
    let startNum = x * (y - 1)
    startCoord = coordArray[startNum]
    dot = SKSpriteNode(imageNamed: "redDot")
    dot.physicsBody?.isDynamic = true
    dot.size = CGSize(width: 20, height: 20)
    dot.position = startCoord
    dot.physicsBody = SKPhysicsBody(circleOfRadius: 10)
    dot.physicsBody?.mass = 0
    dot.physicsBody?.usesPreciseCollisionDetection = true
    self.addChild(dot)
}

 func buildMaze() {
    let difference =  coordArray[1].x - coordArray[0].x 
    let wallDistance = difference/2
    let thickness = CGFloat(3)
    let length = difference  - CGFloat(thickness)/2



    var count = 0
    for point in coordArray {

        let northWall = SKSpriteNode(color: SKColor.black, size : CGSize (width: length, height: thickness))
        northWall.physicsBody = SKPhysicsBody(rectangleOf: CGSize(width: length, height: thickness))
        northWall.physicsBody?.mass = 200000

        let southWall = SKSpriteNode(color: SKColor.black, size : CGSize (width: length, height: thickness))
        southWall.physicsBody = SKPhysicsBody(rectangleOf: CGSize(width: length, height: thickness))
        southWall.physicsBody?.mass = 200000

        let eastWall = SKSpriteNode(color: SKColor.black, size : CGSize (width: thickness, height: length ))
        eastWall.physicsBody = SKPhysicsBody(rectangleOf: CGSize(width: thickness, height: length))
        eastWall.physicsBody?.mass = 200000

        let westWall = SKSpriteNode(color: SKColor.black, size : CGSize (width: thickness, height: length ))
        westWall.physicsBody = SKPhysicsBody(rectangleOf: CGSize(width: thickness, height: length))
        westWall.physicsBody?.mass = 200000


        if !instructions[count].contains("N")  {
            //print("added north wall")
            northWall.position = CGPoint (x: point.x , y: point.y + wallDistance)
            if nodes(at: northWall.position) == [] {

                addChild(northWall)}
            else {print("north wall already there")}

        }
        if !instructions[count].contains("S")  {
            //print("added south wall")
            southWall.position = CGPoint (x: point.x , y: point.y - wallDistance)
            if nodes(at: southWall.position) == [] {

                addChild(southWall)}
            else {//print("southwall already there")

            }

        }
        if !instructions[count].contains("E")  {
            //print("added east wall")
            eastWall.position = CGPoint (x: point.x + wallDistance , y: point.y)
            if nodes(at: eastWall.position) == [] {

                addChild(eastWall)}
            else {//print("east already there")

            }

        }
        if !instructions[count].contains("W")  {
            //print("added west wall")
            westWall.position = CGPoint (x: point.x - wallDistance , y: point.y)
            if nodes(at: westWall.position) == [] {

                addChild(westWall)}
            else {//print("west wall already there")

            }

        }
        count = count + 1

    }
}


    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
        for t in touches {
            let location = t.location(in: self)
            dot.position.x = location.x
            dot.position.y = location.y
        }
    }

func didBegin(_ contact: SKPhysicsContact) {
    print("contact!")


}

墙的外观和我想要的一样，点也在正确的位置。

我为它们中的每一个添加了 20000 的质量，这样当我移动点时，墙壁保持在原位。但是，当我用手指移动圆点时，它只是直接穿过迷宫的墙壁，而不是被它们阻止。

我在 didBegin 函数中添加了一个打印语句，以查看它是否至少检测到精灵之间的任何接触，但它没有。

这是为什么？

干杯！

Answer 1

首先在你的didMoveTo或sceneDidLoad中，你需要设置physicsContactDelegate：

override func sceneDidLoad () {
    physicsWorld.contactDelegate = self
    buildMaze()
    addDot()
}

要设置接触/碰撞掩码，你必须这样做，因为它们是基于位运算的：

假设您希望 dot 和 墙

之间发生碰撞

struct PhysicsCategory {
    static let wall: UInt32 = 0x1 << 1
    static let dot: UInt32 = 0x1 << 2
}

如果你愿意，你可以把结构放在你的类之上

然后，当你分配物理体时，你必须设置位掩码：

对于点：

    dot.physicsBody?.categoryBitMask = PhysicsCategory.dot
    dot.physicsBody?.contactTestBitMask = PhysicsCategory.wall
    dot.physicsBody?.collisionBitMask = PhysicsCategory.wall 

    //Collision is different from contact, so if you want to avoid collision
    //dot.physicsBody?.collisionBitMask = PhysicsCategory.dot 

碰撞与接触不同，查看apple documentation about it

对于墙壁：

    northWall.physicsBody?.categoryBitMask = PhysicsCategory.wall
    northWall.physicsBody?.contactTestBitMask = PhysicsCategory.dot
    northWall.physicsBody?.collisionBitMask = PhysicsCategory.dot

    //Do the same for all walls

如果您希望墙壁与多个物体接触或碰撞：

    northWall.physicsBody?.contactTestBitMask = PhysicsCategory.dot | PhysicsCategory.other
    northWall.physicsBody?.collisionBitMask = PhysicsCategory.dot | PhysicsCategory.other

对于墙壁是有效的，所有考虑都按点计算

Answer 2

当您直接设置精灵的位置时，碰撞和接触检测效果不佳。

在您的代码中，以下行：

        dot.position.x = location.x
        dot.position.y = location.y

直接设置dot 的位置，覆盖物理引擎想要对对象执行的任何操作。

此外，您似乎没有设置任何必要的类别或碰撞/接触测试位掩码。

您允许手动移动点，但使用与墙壁的接触检测，那么您可能需要查看屏幕上的触摸是否在墙内，如果是这种情况，则不要移动点。 （这意味着你根本没有使用物理）。

编辑：我的碰撞和接触分步指南： https://stackoverflow.com/a/51041474/1430420

以及碰撞和接触测试位掩码指南： https://stackoverflow.com/a/40596890/1430420