如何检测重叠的圆和填充颜色？ [英] How to detect overlapping circles and fill color accordingly?

问题描述

我使用3个阵列（对于x，y和半径大小）创建了5个具有随机x和y坐标和半径的圆。但是，我需要圈子根据它们是否与另一个圈子重叠来动态地更改颜色。因此，如果5个圆圈中的一个完全不重叠，则其应该被着色为黑色。重叠圆应为青色。如果两个圆的中心点之间的距离小于它们的半径之和，则两个圆被认为重叠。

I created 5 circles with random x and y coordinates and radii using 3 arrays (for x, y and radius size). However, I need the circles to dynamically change color based on whether or not they overlap with another circle. So if one of the 5 circles doesn't overlap at all, it should be colored black. Overlapping circles should be cyan. Two circles are considered to overlap if the distance between their center points is less than the sum of their radii.

这是我到目前为止为圆类写的。
以下代码将在小程序窗口中成功绘制5个圆，并成功计算距离，但问题是与着色有关。在颜色填充似乎有一个逻辑错误，我没有看到这里的问题。有什么建议么？非常感谢。

This is what I have written so far for the circles class. The following code will successfully draw the 5 circles in an applet window, and the distances are successfully calculated, but the problem is with the coloring. There's seems to be a logic error in the color filling and I don't see the problem here. Any suggestions? Thank you so much.

public class Circles extends Applet {

public void paint(Graphics page)
{
    Random locator = new Random();
    int [] xpt = new int [5];
    int [] ypt = new int [5];
    int [] rad = new int [5];

    setPreferredSize (new Dimension(300, 300));
    for (int i = 0; i < xpt.length; i++){

        xpt[i] = locator.nextInt(100); //need to set a number or it goes into millions, cannot set it in Random()
        ypt[i] = locator.nextInt(100);
        rad[i] = locator.nextInt(100);
        System.out.println("The #" + i +  " x-point: " + xpt[i] + " y-point: " + ypt[i] + " radius: " + rad[i]);  //for debugging purposes

        for (int j = 0; j < xpt.length; j++){
            double xpoint1 = xpt[i]+rad[i];
            double ypoint1 = ypt[i]+rad[i];
            double xpoint2 = xpt[j]+rad[j];
            double ypoint2 = ypt[j]+rad[j];
            double radius1 = rad[i];
            double radius2 = rad[j];
            double theDistance = distance(xpoint1,ypoint1,xpoint2,ypoint2); 
            System.out.println("Comparing " + i + " to " + j); //for debugging and logic checking
            if (i==j)
                ;
            else if (theDistance <= (radius1+radius2))
            {
                page.setColor(Color.cyan);
                page.fillOval(xpt[i], ypt[i], rad[i], rad[i]);
                //page.fillOval(xpt[j], ypt[j], rad[j], rad[j]);
                System.out.println("Overlap occurred. Colored " + i + " and " + j + " cyan.");
                System.out.println("Center points: ("+ xpoint1 +", "+ ypoint1 +") and ("+ xpoint2 + ", "+ ypoint2 + ").");
            }
            else  
            {
                page.setColor(Color.black);
                page.fillOval(xpt[i], ypt[i], rad[i], rad[i]);
                //page.fillOval(xpt[j], ypt[j], rad[j], rad[j]);
                System.out.println("No overlap. Made " + i + " and " + j + " black.");
            }
        }
    }
}

public static double distance(
        double x1, double y1, double x2, double y2) {
    return Math.sqrt((x2 - x1) * (x2 - x1) + (y2 - y1) * (y2 - y1));

}
}

推荐答案

xpoint，ypoint等行不是你所想的。

The xpoint, ypoint, etc. lines are not doing what you think.

如果你想查找两个圆圈是否重叠，你需要找到

If you want to find if two circles are overlapping, you need to find if the distance between the centers of the circles is greater or less than the sum of their radii.

因此：

function circlesCollide(x1, y1, r1, x2, y2, r2){
    return (distance(x1, y1, x2, y2) <= (r1 + r2));
}

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