找点圈在Android [英] Find point on Circle on Android

问题描述

一切都显得那么朴实，直到我不得不实际编程。

我已经得到了

我上传的图像来解释它更好。

• 我有一个圆圈，我知道

  • 在它的半径
  • 在中心点坐标
  • 在每个按钮的初始坐标（红圈）。

我希望能够，当我旋转灰色圆圈形象，10度，计算红色按钮的新坐标（X1Y1，X2Y2）。

这不应该是很难实现的人谁知道数学，但我没能找到一个合适的解决方案。我还搜查在这里，但没有找到一个有效的解决方案。任何帮助是极大的AP preciated。 谢谢

的工作方案，因为菲菲以下所述是：

- 首先照顾旋转角度，每个重绘简单的增加它

  =角度+ mainRotationAngle;

    浮动X =（浮点）（center.X + Math.cos（角度* Math.PI / 180F）*半径
    浮动Y =（浮点）（center.Y + Math.sin（角度* Math.PI / 180F）*半径

    button.setX（X）;
    button.setY（Y）;
 

解决方案

这是easyer如果你保持你的按钮初始的角度的，然后修改角度来产生旋转。所以在伪code：

  newAngle =角度+腐;
xbutton = center.x + COS（newAngle）*半径;
ybutton = center.y +罪（newAngle）*半径;
 

如果你真的只是按钮的坐标，您可以通过使用功能 ATAN2 ，在伪code并将其转换为角度：

  buttonAngle = ATAN2（button.y-center.y，button.x-center.x）;
 

Everything seemed so plain and simple until I had to actually program it.

What I've got

I uploaded an image to explain it better.

• I have a circle and I know

  • it's radius
  • center point coordinates
  • each button's initial coordinates (the red circles).

I want to be able, when I rotate the gray circle image, with 10 degrees, to calculate red buttons new coordinates (x1y1, x2y2).

This shouldn't be hard to achieve for someone who knows math, but I didn't manage to find a suitable solution. I've also searched around here and couldn't find a working solution. Any help is greatly appreciated. Thank you

The working solution, as Felice stated below is:

-first take care of rotation angle, on each redraw simply increment it

   angle = angle+mainRotationAngle;

    float x =  (float) (center.X + Math.cos(angle*Math.PI / 180F) * radius 
    float y =  (float) (center.Y + Math.sin(angle*Math.PI / 180F) * radius

    button.setX(x);
    button.setY(y);

解决方案

It is easyer if you keep with you the button initial angles, then modify the angle to produce the rotation. so in pseudocode:

newAngle = Angle+rot;
xbutton = center.x+cos(newAngle)*radius;
ybutton = center.y+sin(newAngle)*radius;

If you really just have the coordinates of the buttons, you can convert them to the angle by using the function atan2, in pseudocode:

buttonAngle = atan2(button.y-center.y,button.x-center.x);

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