swift 从圆形拍摄物体

Question

我在中间有一个圆圈，我需要向与我接触并从播放器出来的方向相反的方向发射子弹，我写了以下代码但没有任何反应

private func fire(position: CGPoint) {
        let bullet = SKShapeNode(circleOfRadius: 2)
        bullet.strokeColor = SKColor.darkGray
        bullet.fillColor = SKColor.darkGray
        bullet.physicsBody = SKPhysicsBody(circleOfRadius: 2)
        let posX = (position.x) * -1
        let posY = (position.y) * -1
        let pos = CGPoint(x: posX, y: posY)
        bullet.position = pos
        bullet.physicsBody?.affectedByGravity = false
        bullet.physicsBody?.isDynamic = false
        bullet.physicsBody?.pinned = false
        numberOfBullets += 1
        bullet.name = String(numberOfBullets)
        bullet.physicsBody?.collisionBitMask = bodyType.enemy.rawValue
        bullet.physicsBody?.categoryBitMask = bodyType.bullet.rawValue
        bullet.physicsBody?.contactTestBitMask = bodyType.enemy.rawValue
        bullet.physicsBody?.usesPreciseCollisionDetection = true
        world.addChild(bullet)
        bulletForce(bullet: bullet, position: position)
    }

    private func bulletForce(bullet: SKShapeNode, position: CGPoint) {
        let ddx = Double((bullet.position.x - position.x))
        let ddy = Double((bullet.position.y - position.y))
        let degree = atan2(ddy, ddx) * (180.0 / M_PI)
        let magnitude = 900.0
        let angle = degree
        let dx = magnitude * cos(angle)
        let dy = magnitude * sin(angle)
        let vector = CGVector(dx: dx,dy: dy)
        bullet.physicsBody?.applyForce(vector)
        //bullet.run(fire, withKey: "firing\(bullet.name)")
    }

编辑::

由于接受的答案的帮助，这解决了问题

let posX = (position.x) * -1
        let posY = (position.y) * -1
        let pos = CGPoint(x: posX, y: posY)
        let theta = atan2((pos.y - player.position.y), (pos.x - player.position.x))

let dx = cos(theta) /  4
        let dy = sin(theta) /  4
        world.addChild(bullet)
        let vector = CGVector(dx: dx, dy: dy)
        bullet.physicsBody!.applyImpulse(vector)

其中 theta 是我希望子弹到达的角度，这里是

注::

玩家在中间（圆圈）。

posX 和 posY 是用户触摸的 x 和 y 坐标，它们乘以 -1 得到我的子弹将被放置的相反方向。

然后使用 atan2 函数计算角度 theta，而不是将我的子弹远离玩家（圆圈），而是将其定位在圆圈的边缘。

Answer 1

您是否尝试过将 isDynamic 从 "false" 切换到 "true"？另外，尝试添加 GCVector(dx: 1.0 * dx, dy: 1.0 * dy)

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