sprite-kit - applyImpulse 对 CGPoint SpriteKit

Question

我是 SpriteKit 的新手，游戏开发者，事实上我只是在学习。所以我到了一个点，我应该将一堆节点移动到用户点击位置。到目前为止，我一直在努力计算一个虚拟的直角三角形，并根据边得到角的 sin 和 cos。不幸的是，这让我产生了一种非常强烈的冲动，并没有真正考虑用户的点击位置。

有任何想法吗？

提前致谢。

Answer 1

在此处查看 Ray Wenderlich 教程中的射击弹丸部分：

http://www.raywenderlich.com/42699/spritekit-tutorial-for-beginners

将教程中的代码更改如下：

-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {

    // 1 - Choose one of the touches to work with
    UITouch * touch = [touches anyObject];
    CGPoint location = [touch locationInNode:self];

    // 2 - Set up initial location of projectile
    SKSpriteNode * projectile = [self childNodeWithName:@"desirednode"];
    //make projectile point to your desired node.

    // 3- Determine offset of location to projectile
    CGPoint offset = rwSub(location, projectile.position);

    // 4 - Bail out if you are shooting down or backwards. You can ignore this if required.
    if (offset.x <= 0) return;

    // 5 - OK to add now - we've double checked position
    [self addChild:projectile];

    // 6 - Get the direction of where to shoot
    CGPoint direction = rwNormalize(offset);

    // 7 - Make it shoot far enough to be guaranteed off screen
    float forceValue = 200; //Edit this value to get the desired force.
    CGPoint shootAmount = rwMult(direction, forceValue);

    //8 - Convert the point to a vector
    CGVector impulseVector = CGVectorMake(shootAmount.x, shootAmount.y);
    //This vector is the impulse you are looking for.

    //9 - Apply impulse to node.
    [projectile.physicsBody applyImpulse:impulseVector];

}

代码中的 projectile 对象代表您的节点。此外，您将需要编辑 forceValue 以获得所需的脉冲。