如何选择最短的旋转方向成一个角度 [英] How to get to an angle choosing the shortest rotation direction

问题描述

我的游戏中有一个角色，必须平稳旋转才能达到所需的角度.将angle设为当前角度，将touchAngle设为所需角度，该角度始终在0到360之间.我想在每次游戏更新中为当前角度添加+ 1/-1，以达到所需的touchAngle.问题是首先必须选择方向，并且必须在0到360之间.这是我的伪代码:

I have a character in my game that must rotate smoothly to get to a desired angle. Consider angle as the current angle and touchAngle as the desired angle which is always between 0 to 360. I want to add +1/-1 to current angle in every game update to get to the desired touchAngle. The problem is first it must chose direction and it must be between 0 to 360. this is my pseudo code:

int touchAngle;
float angle;
public void update()
{
    if ((int)angle != touchAngle) angle += ???
}

推荐答案

由于您的值始终在[0 360]间隔中进行规范化，因此这应该不太困难. 您只需要区分两种不同的情况:

Since you have values that are always normalized in the interval [0 360] this should not be too hard. You just need to distinguish two different cases:

angle < touchAngle
angle > touchAngle

在第一种情况下，我们想逆时针旋转，因此更新必须为angle =+ 1(假设您希望在每个更新周期将其设置为1). 在第二种情况下，我们想顺时针旋转，因此更新应为angle -= 1.

in the first case we want to rotate counterclockwise so the update has to be angle =+ 1 (assuming that you want to turn of 1 every update cycle). In the second case we want to turn clockwise so the update should be angle -= 1.

问题在于，这并不总是最短的旋转方式.例如，如果:

The problem is that this is not always the shortest way to rotate. For instance if:

angle == 359
touchAngle == 1

我们不想一直走到358、357、356 ...相反，我们只想逆时针旋转2个单位:360、1. 比较角度abs(angle - touchAngle)之间的距离即可实现.

we don't want to make all the way 358, 357, 356...instead we want to rotate counterclockwise for just 2 units: 360, 1. This can be achieved comparing the distance between the angles abs(angle - touchAngle).

如果此值大于180，则表示我们走错了路，所以我们必须这样做.

If this value is bigger than 180 it means we are going the wrong way, so we have to do the way around so

if(angle < touchAngle) {
    if(abs(angle - touchAngle)<180)
       angle += 1;
    else angle -= 1;
}

else {
    if(abs(angle - touchAngle)<180)
       angle -= 1;
    else angle += 1;
}

当然，所有这一切直到((int)angale != touchAngle). 我可能在这些案例上犯了错误，但这是原则.

of course all of this until ((int)angale != touchAngle). I might have made mistakes with the cases but this is the principle.

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