绘制围绕圈子的小线的数学 [英] mathematics for drawing little lines around circle

问题描述

我必须在一个圆周（如时钟）画线。我怎么能实现这个使用一个for循环？

I have to draw lines around a circle (like in clock). How can i achieve this using a for loop?

推荐答案

我不知道如何在Java中实际绘制一条线，但是从中心点计算坐标（cx，cy） use

I'm not sure how to do the actual drawing of a line in Java but to calculate co-ordinates from a central point (cx,cy) use

px = cx+sin(a)*r
py = cy+cos(a)*r

其中 a - 我认为是180degress =π弧度）和 r 是半径。

Where a is the angle (in radians - I think ie 180 degress=π radians) and r is the radius.

外部你需要使用这个公式，半径为100，半径为105，并在两组坐标之间绘制。

To draw the little lines around the outside you would need to use this formula with say a radius of 100 and the also with a radius of 105 and draw between the two sets of co-ordinates.

例如

for (var a=0,aMax=(2*Math.PI),aStep=(Math.PI/30); a<aMax; a+=aStep){
    px1 = cx+Math.sin(a)*r;
    py1 = cy+Math.cos(a)*r;
    px2 = cx+Math.sin(a)*(r+5);
    py2 = cy+Math.cos(a)*(r+5);

    //draw line between (px1,py1) and (px2,py2)
};

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