swift - 为什么 applyImpulse 在 swift spritekit 中不起作用？

Question

在我的游戏中，当用户触摸屏幕时，使用 func fire() 创建了一颗子弹，但没有任何反应。

以下是我的代码:

private func fire(position: CGPoint) {
        let bullet = SKShapeNode(circleOfRadius: 2)
        bullet.strokeColor = SKColor.darkGray
        bullet.fillColor = SKColor.darkGray
        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 finalPos = CGPoint(x: (player.position.x) + (CGFloat(playerRadius) * cos(theta)), y: (player.position.y) + (CGFloat(playerRadius) * sin(theta)))
        bullet.physicsBody = SKPhysicsBody(circleOfRadius: 2)
        bullet.position = finalPos
        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)
    }

    private func bulletForce(bullet: SKShapeNode) {
        let dx = Double((bullet.position.x - player.position.x))
        let dy = Double((bullet.position.y - player.position.y))
        let vector = CGVector(dx: dx, dy: dy)
        bullet.physicsBody!.applyImpulse(vector)
    }

提前致谢。

Answer 1

它失败的原因是因为你有 isDynamic = false。

isDynamic 表示可以对 body 施加力。

更多阅读请看: 阅读 developer.apple.com/reference/spritekit/skphysicsbody