2

So, I am making a program that currently draws filled circles of a random size (between 6-9 inclusive) randomly on a JFrame of size 1024x768. The problem I am having, is that even after I coded in a rule that should ensure that all the circles fall within the 1024x768 JFrame, the circles fall outside of the desired boundaries. Below is the code segment that should generate the correct location for each circle:

private static KillZoneLocation generateLocation(){
    int genX,genY;
    int xmax = 1024 - generatedGraphic.getRadius();
    int ymax = 768 - generatedGraphic.getRadius();
    KillZoneLocation location = new KillZoneLocation();
    do{
        genX = generatedGraphic.getRadius() + (int)(Math.random()*xmax);
        genY = generatedGraphic.getRadius() +(int)(Math.random()*ymax);
        location.setXcoord(genX);
        location.setYcoord(genY);
        generatedLocation = location;
    }while(isOverlaping(location));

    return location;
}

generatedGraphic is a global variable from the class containing the method above and returns a number between 6 and 9 inclusive

generatedGraphic.getRadius() returns a random number from this algorithm int radius = 7 + (int)(Math.random()*9); The number has been generated prior by a different method. This method is just a getter. The radius number is not generated every time this method is called.

isOverlaping(locations) just checks to make sure the circle does not overlap another circle that is already placed on the JFrame.

location.set... Those are just setter methods.

I'm thinking this is just a silly logic error, but I still can't seem to figure out why the circles are printing outside of the frame.

I am purposely avoiding posting anymore code because it will confuse you since the program has a much larger scope then I have described and there are a dozen files all interwinded. I debugged this code and realized numbers being returned by: genX = generatedGraphic.getRadius() + (int)(Math.random()*xmax); genY = generatedGraphic.getRadius() +(int)(Math.random()*ymax);

Return numbers out of range.

Draw class:

import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import javax.swing.*;

public class KillZoneGUI extends JFrame{

    public KillZoneGUI(){
        setSize(1024,768);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLocationRelativeTo(null);
        setVisible(true);

    }

    public static void main(String s[]) {
        GenerateKillZone.setup(1024,768);
        new KillZoneGUI();
    }

    public void paint(Graphics g){
        for(Robot r: KillZone.getRobots()){
            g.setColor(r.getGraphic().getColor());
            g.fillOval(
                       r.getLocation().getXcoord(), 
                       r.getLocation().getYcoord(),
                       r.getGraphic().getRadius(),
                       r.getGraphic().getRadius()); 
        }

   }
}
4

2 回答 2

1

正确的代码应该是

genX = (int)(Math.random()*xmax);
genY = (int)(Math.random()*ymax);

请记住，Graphics2D.fillOval()将使用 genX/genY 作为左上角，并且椭圆将扩展 getRadius() 的值。您正在减去半径的大小，然后将其加回两次！一次是在您的 genX/Y 分配中，一次是在您绘制椭圆时。

于 2013-03-20T13:57:15.760 回答
0 
int xmax = 1024 - 2 * generatedGraphic.getRadius();
int ymax = 768 - 2 * generatedGraphic.getRadius();

当您从 generatedGraphic.getRadius(); 开始时 并且可能只达到 xmax/ymax。

然后使用@JasonNichols 的答案，从 (left, top) (0, 0) 开始的 fillOval 到宽度 - 直径。

于 2013-03-20T13:53:18.167 回答