在SpriteKit中将物理物体添加到Sprite中会部分改变其位置 [英] Adding physics body to Sprite in SpriteKit alters its position fractionally

问题描述

我有一个Swift/SpriteKit游戏，其中一堆精灵都有物理物体来检测与玩家的碰撞-否则它们不应该移动.

I have a Swift / SpriteKit game in which a whole bunch of sprites have physics bodies to detect collision with the player - but otherwise they are not supposed to move.

我的问题是，一旦我添加了一个物理物体，精灵就会出现部分移动.更具体地说，其位置变化很小(例如0.0003).最初，这么小的变化并不重要，但它会一直这样变化，直到精灵实际在屏幕上移动并弄乱游戏为止.

My issue is that as soon as I add a physics body, the sprite appears to move fractionally. More specifically its position changes by a small fraction (like 0.0003). Initially such a small change does not matter, but it keeps changing like this until the sprite actually moves onscreen and messes up the game.

为了缩小范围，我创建了一个仅包含一个精灵的简单项目，并且我注意到，只要将物理物体附着到我的精灵上，其位置就会发生部分偏移.

To narrow it down I created a simple project with just one sprite and I notice that as soon as I attach a physics body to my sprite its position shifts fractionally.

我已经尝试过的事情:

1. 检查以确保重力已关闭
2. 将物理物体的静止属性设置为真
3. 将物理物体的重力属性影响设置为false

在OS X上使用Xcode进行Im编码

Im coding using Xcode on OS X

但是没有运气.

下面是一个代码片段，在测试项目中对此进行了显示:

Here's a code fragment which shows this in the test project:

import SpriteKit


class TestScene: SKScene, SKPhysicsContactDelegate {

  let sprite1 = SKSpriteNode(color: SKColor.redColor(), size: CGSizeMake(50, 50))

override func didMoveToView(view: SKView) {

    physicsWorld.gravity = CGVectorMake(0.0, 0.0)
    physicsWorld.contactDelegate = self

    sprite1.position = CGPointMake(200, 200)
    sprite1.physicsBody = SKPhysicsBody(rectangleOfSize: sprite1.size)
    sprite1.physicsBody?.affectedByGravity = false
    sprite1.physicsBody?.resting = true

    self.addChild(sprite1)
    sprite1.position = CGPointMake(200, 200)

  }


  override func update(currentTime: NSTimeInterval) {
    print(sprite1.position)

    // position is not 200,200 as expected
    // it becomes 199.999938964844, 199.999938964844 after a few updates
    // In my real project the position will keep drifting like this until it moves on screen

  }

}

推荐答案

我认为它的dynamic属性默认情况下设置为yes.将其设置为false，精灵将不再移动

I think its the dynamic property which is set to yes by default. Set it to false and the sprite should not move anymore

sprite1.physicsBody?.dynamic = false

我刚刚在一个项目中对此进行了测试，它仍然显示为199.9 ....但它似乎并没有增加或减少

I just tested this in a project and it still says 199.9.... but it doesnt seem to increase or decrease

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