在圆上绘制点

Question

我在 java 中玩耍，并试图创建我自己的观点版本 class:

public class Location {
    public double x, y;

    public Location(double x, double y) {
        this.x = x;
        this.y = y;
    }

    public double dist(Location location) {
        return Math.sqrt(Math.pow(location.x - x, 2) + Math.pow(location.y - y, 2));
    }

    //Rotates the point the amount in angle around the point center
    public void rotate(Location center, double angle) {
        //Also tried this
        /*double current = Math.atan2(center.y - y, center.x - x);
        x = center.x + (Math.cos(current + angle) * dist(center));
        y = center.y + (Math.sin(current + angle) * dist(center));*/
        //Current code
        x = center.x + (Math.cos(angle) * dist(center));
        y = center.y + (Math.sin(angle) * dist(center));
    }
}

但是，无论我怎样尝试，rotate() 函数返回的数据都略有偏差。此函数输出的不是完美的圆，而是一个奇怪的缩小形状。

public class Circle {

    //Should output circle
    public static void main(String[] args) {
        for (int i = 0; i < 18; i++) {
            Location point = new Location(100, 100);
            point.rotate(new Location(200, 200), Math.toRadians(i * 20));
            System.out.print("(" + point.x + ", " + point.y + ")");
        }
    }
}

当我把这些坐标输出到this plotting site this is the image I get:

我的数学和Java: Plotting points uniformly on a circle using Graphics2d一样，所以我不知道发生了什么。

Answer 1

计算 dist(center) 一次，将其存储在一个变量中，然后使用该变量更新 x 和 y:

double d = dist(center);
x = center.x + (Math.cos(angle) * d);
y = center.y + (Math.sin(angle) * d);

dist(center)依赖于x，所以在计算y.

的新值时更新x后会得到不同的值

在圆上绘制点

Plotting Points on Circle

java

trigonometry

rotation