Question

我正在查看this drag and drop tutorial by Ray Wenderleich，它允许在屏幕上拖动精灵，但是，没有重力，并且一旦用户抬起手指，精灵就会被固定到位。

与此同时looking at this SpriteKit collision demo by Apple，它在对象之间发生了碰撞。

然后有this tutorial which shows how to apply impulse to sprites.

我将演示组合在一起，所以我的场景有重力，边缘碰撞和弹跳，但拖放代码仍然没有惯性。

如何将拖放行为修改为＆＃34;拖放＆＃34;对于精灵？我正在寻找类似于滚动视图中的视图的行为 - 加速度，减速度和惯性。

下面的代码有两种模式 - 轻弹，将脉冲应用于精灵，拖动，改变精灵的位置。我不确定如何将两个代码路径组合到

- (void)handlePanFrom:(UIPanGestureRecognizer *)recognizer {

    CGPoint touchLocation = [recognizer locationInView:recognizer.view];

    touchLocation = [self convertPointFromView:touchLocation];

    if (recognizer.state == UIGestureRecognizerStateBegan) {

        [self selectNodeForTouch:touchLocation];

    } else if (recognizer.state == UIGestureRecognizerStateChanged) {




        SKNode* node = [self selectNodeForTouch:touchLocation];

        //this is the flick gesture - pings the 
         double angle = atan2(touchLocation.y-node.position.y,touchLocation.x-node.position.x);
        [node.physicsBody applyImpulse:CGVectorMake(20*cos(angle), 20*sin(angle))];

        //CGPoint translation = [recognizer translationInView:recognizer.view];
 //       translation = CGPointMake(translation.x, -translation.y);
 //       [self panForTranslation:translation];
 //       [recognizer setTranslation:CGPointZero inView:recognizer.view];

    } else if (recognizer.state == UIGestureRecognizerStateEnded) {



    }
}

这是拖放代码：

- (void)panForTranslation:(CGPoint)translation {
    CGPoint position = [_selectedNode position];
    if([[_selectedNode name] isEqualToString:kAnimalNodeName]) {
        [_selectedNode setPosition:CGPointMake(position.x + translation.x, position.y + translation.y)];
    } else {
        CGPoint newPos = CGPointMake(position.x + translation.x, position.y + translation.y);
        [_background setPosition:[self boundLayerPos:newPos]];
    }
}

Answer 1

当pan识别器将状态更改为结束时，您需要应用脉冲。在拖动过程中使物理体静止也是个好主意。最好的地方是touchesBegan，因为它是最快的。这是我在swift中的代码示例。

func handlePan(panGestureRecognizer recognizer:UIPanGestureRecognizer) {
        let touchLocationView = recognizer.location(in: recognizer.view)
        let touchLocationScene = self.convertPoint(fromView: touchLocationView)

        switch recognizer.state {
        case .began:
            let canditateNode = self.touchedNode(touchLocationScene)
            if let name = canditateNode.name, name.contains(kMovableNode) {
                self.selectedNode = canditateNode
            }
        case .changed:
            let translation = recognizer.translation(in: recognizer.view)
            if let position = self.selectedNode?.position {
                self.selectedNode?.position = CGPoint(x: position.x + translation.x, y: position.y - translation.y)
                recognizer.setTranslation(CGPoint.zero, in: recognizer.view)
            }
        case .ended:
            self.selectedNode?.physicsBody?.isDynamic = true;
            let velocity = recognizer.velocity(in: recognizer.view)
            self.selectedNode?.physicsBody?.applyImpulse(CGVector(dx: velocity.x, dy: -velocity.y))
            self.selectedNode = nil
        default:
            break
        }
    }
    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
            NSLog("touchesBegan")
            if let touch = touches.first {
                let touchLocationScene = touch.location(in: self)
                let canditateNode = self.touchedNode(touchLocationScene)
                if let name = canditateNode.name, name.contains(kMovableNode) {
                    self.selectedNode = canditateNode
                    self.selectedNode?.physicsBody?.isDynamic = false
                }
            }
        }

iOS8 SpriteKit怎么做惯性拖放（用手指轻弹）？

1 个答案: