Question

我有一张包含40张旋转图像的图像。

实际上图像索引从0到39开始。

这是将0-39转换为度

的代码

int image_direction = 0; //Can be 0-39
int facing_degrees = (int)(360.0 * (-(image_direction- 10.0))/40.0);
while(facing_degrees < 0)
    facing_degrees += 360;
while (facing_degrees > 360)
    facing_degrees -= 360;

所以是的，它也可以给出负度以及度数超过360.所以这就是为什么有2个while循环。

现在我希望扭转这个过程说我指定90度我想回来0 ..

我在考虑做类似

的事情

 if(degrees == 90 || degrees >= 80 && degrees <= 99)
    image_direction = 0;
 elseif(degrees == 100 || degrees >= 91 && degrees <= 109)
    image_direction = 39;
//etc.......

嗯，我不擅长数学，我忘记了这种东西。

我想知道你怎么能扭转这个函数，它使image_direction的度数在一个简单的等式中向后运行，以避免if语句的大量情况。

以下是一些结果 rotation results

Image Index = 0 Image Degree = 90
Image Index = 1 Image Degree = 81
Image Index = 2 Image Degree = 72
Image Index = 3 Image Degree = 63
Image Index = 4 Image Degree = 54
Image Index = 5 Image Degree = 45
Image Index = 6 Image Degree = 36
Image Index = 7 Image Degree = 27
Image Index = 8 Image Degree = 18
Image Index = 9 Image Degree = 9
Image Index = 10 Image Degree = 0
Image Index = 11 Image Degree = 351
Image Index = 12 Image Degree = 342
Image Index = 13 Image Degree = 333
Image Index = 14 Image Degree = 324
Image Index = 15 Image Degree = 315
Image Index = 16 Image Degree = 306
Image Index = 17 Image Degree = 297
Image Index = 18 Image Degree = 288
Image Index = 19 Image Degree = 279
Image Index = 20 Image Degree = 270
Image Index = 21 Image Degree = 261
Image Index = 22 Image Degree = 252
Image Index = 23 Image Degree = 243
Image Index = 24 Image Degree = 234
Image Index = 25 Image Degree = 225
Image Index = 26 Image Degree = 216
Image Index = 27 Image Degree = 207
Image Index = 28 Image Degree = 198
Image Index = 29 Image Degree = 189
Image Index = 30 Image Degree = 180
Image Index = 31 Image Degree = 171
Image Index = 32 Image Degree = 162
Image Index = 33 Image Degree = 153
Image Index = 34 Image Degree = 144
Image Index = 35 Image Degree = 135
Image Index = 36 Image Degree = 126
Image Index = 37 Image Degree = 117
Image Index = 38 Image Degree = 108
Image Index = 39 Image Degree = 99
Image Index = 0 Image Degree = 90
Image Index = 1 Image Degree = 81
Image Index = 2 Image Degree = 72
Image Index = 3 Image Degree = 63
Image Index = 4 Image Degree = 54
Image Index = 5 Image Degree = 45
Image Index = 6 Image Degree = 36
Image Index = 7 Image Degree = 27
Image Index = 8 Image Degree = 18

Answer 1

嗯，为什么不通过一些调整来使用类似于“百分比公式”的东西：

image_direction = (int)(((float)(degrees-90) / 360) * 40) % 40;
if (image_direction < 0)
    image_direction += 40; // for negative integers

打破公式;我们将度数除以360并乘以40以得到给定指定度数的正确图像，然后我们使用模运算符将image_direction保持在0-39范围内，对于度数＆gt; +360或＆lt; -360最后，如果度数是负数，则image_direction将变为负数，因此向其添加40将校正image_direction。

希望这会有所帮助。

编辑：哦对不起，我似乎错过了关于90 ==图像索引0的部分，这里很容易添加，只是从实际程度减去90（上面编辑的代码）

Answer 2

从输入到输出的映射，我将它们粘贴到Excel中，并确定计算度数的公式如下：

RawDegrees = 90 - (index * 9)

然后将其剪裁为0 ... 360（使用while循环回绕），您将获得最终的度数输出。通过重新排列上述内容使索引成为主题

，可以找到反转它的公式

    RawDegrees - 90 = - (index * 9) --- 1
    RawDegrees/9.0 - 10 = -index    --- 2

    Therefore
    index = 10 - Degrees/9.0

这将为您提供以下映射

    Degree  Discovered Index
    90      0
    81      1
    72      2
    63      3
    54      4
    45      5
    36      6
    27      7
    18      8
    9       9
    0       10
    351     -29
    342     -28
    333     -27
    324     -26
    315     -25
    306     -24
    297     -23
    288     -22
    279     -21
    270     -20
    261     -19
    252     -18
    243     -17
    234     -16
    225     -15
    216     -14
    207     -13
    198     -12
    189     -11
    180     -10
    171     -9
    162     -8
    153     -7
    144     -6
    135     -5
    126     -4
    117     -3
    108     -2
    99      -1
    90      0
    81      1
    72      2
    63      3
    54      4
    45      5
    36      6
    27      7
    18      8

您需要做的就是执行环绕以将答案剪辑为0..39，例如

index = index < 0 ? index + 40 : index;

获得正确的输出。

顺便提一下，您的度数代码索引可以按如下因素分解，以获得相同的输出（对于输入0..39有效）

int facing_degrees = (int)(90.0 - (image_direction * 9.0));    
facing_degrees = facing_degrees < 0 ? facing_degrees + 360 : facing_degrees;

如何将度（角度）转换为面对数

2 个答案: