iphone - 如何实现像把球扔进桶里的效果？

Question

我是 Cocos2d 的新手，因此不了解大多数类和函数。在我的应用程序中，我想实现一个模块，例如触摸并沿桶的方向拖动球将传递球并将球放入桶中。我能够朝该方向传球，但随后它就会按照坐标(x.y)离开屏幕。

    - (void)ccTouchesEnded:(NSSet *)touches withEvent:(UIEvent *)event 
    {
        // Choose one of the touches to work with
        UITouch *touch = [touches anyObject];
        CGPoint location = [touch locationInView:[touch view]];
        location = [[CCDirector sharedDirector] convertToGL:location];

        //  Determine offset of location to projectile
        int offX = location.x - ball.position.x;
        int offY = location.y - ball.position.y;

        // Bail out if we are shooting down or backwards
        if (offX <= 0)
            return;

        // Determine where we wish to shoot the projectile to
        int realX = winSize.width + (ball.contentSize.height/2);
        float ratio = (float) offY / (float) offX;
        int realY = (realX * ratio) + ball.position.y;
        CGPoint realDest = ccp(realX, realY);

        if(realX>=320)
            realX = 320;
        if(realY>=480)
            realY = 480;
        CGPoint realDest = ccp(realX, realY);

        int good = goodBarrel.position.x;
        int bad = badBarrel.position.x;

        int destY = realDest.x;
        if(destY<=good)
            destY = good;

        if(destY>=bad)
            destY = bad;

        realDest.x = destY+10;

        // Determine the length of how far we're shooting
        int offRealX = realX - ball.position.x;
        int offRealY = realY - ball.position.y;
        float length = sqrtf((offRealX*offRealX)+(offRealY*offRealY));
        float velocity = 480/1; // 480pixels/1sec
        float realMoveDuration = length/velocity;

        // Move projectile to actual endpoint
        [ball runAction:[CCSequence actions:
                               [CCMoveTo actionWithDuration:realMoveDuration position:realDest],
                               [CCCallFuncN actionWithTarget:self selector:@selector(spriteMoveFinished:)],
                               nil]];                         
}

我需要做类似的事情，它将了解桶的位置并找到桶的顶部，并将球放在桶的中心，并且在移动球时，球的大小会减小到产生将球扔到远处的效果。 GoodBarrel 和 BadBarrel 是我放在球对面的两个桶，以便将球放在同一个地方。有什么功能或方法我可以使用吗？

Answer 1

紧接着 [ball runAction: .... ];行，您可以同时对同一对象运行另一个操作。添加一个

[ball runAction:[CCScaleTo actionWithDuration:realMoveDuration scale:0.4f];

这两个 Action 将同时完成，提供您想要创建的距离的“幻觉”。