从上图中,给定初始位置b0(x,y),b1(x,y)的结束位置和a(x,y)和c(x,y)的位置。如何在不与矩形A和C接触的情况下预先确定方形B0是否从b0(x,y)移动到b1(x,y)?我相信这个角度是必要的。
答案 0 :(得分:11)
一些观察......
如果方框B的初始位置位于结束位置的右侧(在间隙中),则只有当theta是逆时针方向时,方框才能成功移动到结束位置而不会与其他方框发生碰撞角度(见下图)。对于此测试,请使用方框B的右上角和C的左下角。
类似地,如果方框B的初始位置在结束位置的左侧,那么只有当theta是逆时针角度时,它才能成功地移动到结束位置而不与其他方框发生碰撞(见图下面)。对于此测试,请使用方框B的左上角和A的右下角。
一些代码......
首先,展开CGPoint
以确定方框的角落。
extension CGPoint {
func bottomLeftCorner(size:CGSize) -> CGPoint {
return CGPoint (x:x - size.width/2.0, y:y - size.height/2.0)
}
func bottomRightCorner(size:CGSize) -> CGPoint {
return CGPoint(x:x + size.width/2.0, y:y - size.height/2.0)
}
func topLeftCorner(size:CGSize) -> CGPoint {
return CGPoint (x:x - size.width/2.0, y:y + size.height/2.0)
}
func topRightCorner(size:CGSize) -> CGPoint {
return CGPoint(x:x + size.width/2.0, y:y + size.height/2.0)
}
}
以下代码允许用户删除/拖动框B.当用户移动框时,代码会执行即时测试以查看框是否可以移动到间隙而不会与其他框冲突。
class GameScene: SKScene {
let size1 = CGSize(width: 100, height: 50)
let size2 = CGSize(width: 50, height: 50)
let size3 = CGSize(width: 100, height: 50)
var boxA:SKSpriteNode!
var boxB:SKSpriteNode!
var boxC:SKSpriteNode!
var center:CGPoint!
override func didMove(to view: SKView) {
// This is box B's ending position
center = CGPoint (x:0,y:0)
// Define and add the boxes to the scene
boxA = SKSpriteNode(color: SKColor.yellow, size: size1)
boxB = SKSpriteNode(color: SKColor.red, size: size2)
boxC = SKSpriteNode(color: SKColor.blue, size: size3)
boxA.position = CGPoint(x: -size1.width, y: 0)
boxB.position = CGPoint(x: 0, y: 0)
boxC.position = CGPoint(x: size3.width, y: 0)
boxB.zPosition = 1
addChild(boxA)
addChild(boxB)
addChild(boxC)
}
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
for touch in touches {
let location = touch.location(in: self)
// Allow user to drag box to a new location
boxB.position = location
// Find the appropriate corners
var cornerA:CGPoint!
var cornerB:CGPoint!
var cornerC:CGPoint!
if (boxB.position.x < center.x) {
cornerA = boxA.position.bottomRightCorner(size: boxA.size)
cornerB = boxB.position.topLeftCorner(size: boxB.size)
cornerC = center.topLeftCorner(size: boxB.size)
}
else {
cornerA = center.topRightCorner(size: boxB.size)
cornerB = boxB.position.topRightCorner(size: boxB.size)
cornerC = boxC.position.bottomLeftCorner(size: boxC.size)
}
// Test if box B can move in the gap without colliding
if isCounterClockwise(A: cornerA, B: cornerB, C: cornerC) {
boxB.color = SKColor.green
}
else {
boxB.color = SKColor.red
}
}
}
override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
// Move box B to the ending position
let action = SKAction.move(to: center, duration: 2)
boxB.run(action)
}
// Test direction of angle between line segments AB and AC
func isCounterClockwise (A:CGPoint, B:CGPoint, C:CGPoint) -> Bool {
return (C.y-A.y)*(B.x-A.x) > (B.y-A.y)*(C.x-A.x)
}
}
和视频剪辑......
如果Box B可以移动到间隙而不发生碰撞,则变为绿色,否则变为红色。