用于找出圆周上的像素坐标的算法 [英] algorithm for finding out pixel coordinates on a circumference of a circle

问题描述

如果我知道圆心的像素坐标，圆的半径和垂直角度，我如何在圆周上找出一定程度的像素值。
基本上，我试图在不同的时间（1点钟，2点钟等）绘制一个时钟的手

how do i find out pixel value at certain degree on the circumference of a circle if I know the pixel co-ordinates of the center of the circle, radius of the circle ,and perpendicular angle. Basically, I am trying to draw the hands of a clock at various times ( 1 o clock , 2 o clock etc )

推荐答案

h 是一个浮点数（ h = 2.25 ）将是02:15，等等）在0和12之间。（cX，cY）是中心的坐标。 hLength 和 mLength 是时针和分针的长度。

Let h be the hour as a floating point number (h=2.25 would be 02:15, etc.) between 0 and 12. (cX,cY) are the coordinates of the center. hLength and mLength are the lengths of the hour and min hands.

// Hour hand
hAngle = 2.0*Pi*h/12.0; // 0..12 mapped to 0..2*Pi
hX = cX + hLength * sin(hAngle);
hY = cY - hLength * cos(hAngle);

// Min hand
mAngle = 2.0*Pi*h; // 0..1 mapped to 0..2*Pi, etc.
mX = cX + mLength * sin(mAngle);
mY = cY - mLength * cos(mAngle);

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