Question

我在太空射击游戏中有一个寻热导弹跟随一个移动的目标。导弹跟随移动目标足够好，但我希望它能够不断向目标方向旋转。我目前的代码如下：

   -(void)updateHeatSeekerAngleTo:(CGPoint)direction
   {
       CGFloat angle = atan2f(direction.y, direction.x);
       _heatSeeker.zRotation = angle;       
   }

然后在didSimulatePhysics中调用此方法（因为这比使用以下更新:)：

[self updateHeatSeekerAngleTo:_target.position];

如前所述，导弹精美地跟随移动目标，然而，它具有非常延迟的旋转效果，并且经常在侧向位置跟随移动目标，然后当它越近时最终指向目标。我在静止的导弹精灵上测试了代码，当目标移动时，固定导弹不断地指向目标，但是当导弹运动时它不会这样做。怎样才能使导弹在运动中不断指向移动目标？

Answer 1

当你向其发射导弹时，听起来你的目标正在部署对策......

除了笑话，我怀疑这可能是你没有考虑的90度偏移。节点的zRotation＆＃34;零＆＃34;角度实际上在节点的右边，或者我们会考虑90度。这可能会在处理角度时出现很多混乱，零点直接上升。

查看下面的示例项目代码。您可以点击/单击并拖动屏幕周围的方块，导弹尖端将跟踪目标。您可以使用该代码来纠正您的问题。

#import "GameScene.h"
@implementation GameScene {
     SKSpriteNode *node0;
     SKSpriteNode *node1;
}

-(void)didMoveToView:(SKView *)view {
    self.backgroundColor = [SKColor whiteColor];

    node0 = [SKSpriteNode spriteNodeWithColor:[SKColor grayColor] size:CGSizeMake(50, 50)];
    node0.position = CGPointMake(500, 500);
    [self addChild:node0];

    node1 = [SKSpriteNode spriteNodeWithColor:[SKColor blackColor] size:CGSizeMake(10, 50)];
    node1.position = CGPointMake(300, 350);
    [self addChild:node1];

    SKSpriteNode *node0Tip = [SKSpriteNode spriteNodeWithColor:[SKColor redColor] size:CGSizeMake(10, 10)];
    node0Tip.position = CGPointMake(0, 25);
    [node1 addChild:node0Tip];
}

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    for (UITouch *touch in touches) {
        CGPoint touchLocation = [touch locationInNode:self];

        node0.position = touchLocation;

        // calculate angle between object and touch
        float deltaY = touchLocation.y - node1.position.y;
        float deltaX = touchLocation.x - node1.position.x;
        float moveBydegrees = atan2(deltaY, deltaX) * 180 / 3.14159265359;

        // convert degrees to radians
        float moveByRadians = moveBydegrees * M_PI / 180;

        node1.zRotation = (moveByRadians-1.5707963268); // account for 90 degree offset
    }
}


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

     for (UITouch *touch in touches) {
         CGPoint touchLocation = [touch locationInNode:self];

        node0.position = touchLocation;

        // calculate angle between object and touch
        float deltaY = touchLocation.y - node1.position.y;
        float deltaX = touchLocation.x - node1.position.x;
        float moveBydegrees = atan2(deltaY, deltaX) * 180 / 3.14159265359;

        // convert degrees to radians
        float moveByRadians = moveBydegrees * M_PI / 180;

        node1.zRotation = (moveByRadians-1.5707963268); // account for 90 degree offset
    }
}

为什么我的移动精灵在Sprite Kit中有延迟旋转？

1 个答案: