4

我一直在尝试编写代码来生成随机三角形并在三角形的相邻边缘之间绘制弧线以描述它们之间的角度。它几乎可以工作。但似乎我的数学在某处失败了，并且在某些运行中没有正确绘制弧线。

请告诉我哪里出错了。也许这些线是因素：

            g.draw(new Arc2D.Double(x1-r,y1-r,2*r,2*r,0,a,Arc2D.OPEN));
            g.draw(new Arc2D.Double(x2-r,y2-r,2*r,2*r,(180-b),b,Arc2D.OPEN));
            g.draw(new Arc2D.Double(x3-r,y3-r,2*r,2*r,-180+a,c,Arc2D.OPEN));

这是SSCCE：

            import javax.swing.JComponent;
        import javax.swing.JFrame;
        import java.awt.geom.*;
        import java.awt.*;
        import java.util.*;
        class MyCanvas extends JComponent {
            int a,supb,b,c,length,r;
            double x1,y1,x2,y2,x3,y3;
            Random random=new Random();
            public MyCanvas(){
                a=random.nextInt(80-30)+30;
                supb=random.nextInt(120-70)+100;
                b=180-supb;
                c=180-a-b;
                length=random.nextInt(150-100)+100;
                x1=0;
                y1=0;
                r=20;
                x2=x1+length;
                y2=y1;
                x3=(x1+Math.cos(Math.toRadians(-a))*length);
                y3=(y1+Math.sin(Math.toRadians(-a))*length);
            }
         public void paintComponent(Graphics g2){

                Graphics2D g=(Graphics2D) g2;
                Random random=new Random();
                AffineTransform oldt=g.getTransform();
                Shape shape=getTriangle(x1,y1,x2,y2,x3,y3);
                Rectangle2D bounds=shape.getBounds2D();
                double height=bounds.getHeight();
                double width=bounds.getWidth();
                g.setRenderingHint(RenderingHints.KEY_ANTIALIASING,RenderingHints.VALUE_ANTIALIAS_ON);
                g.setStroke(new BasicStroke(2.0f, BasicStroke.CAP_BUTT, BasicStroke.JOIN_BEVEL));
                g.translate((this.getWidth() - width) / 2,(this.getHeight() - height) / 2);
                g.translate(-bounds.getX(),-bounds.getY());
                g.draw(shape);
                g.draw(new Arc2D.Double(x1-r,y1-r,2*r,2*r,0,a,Arc2D.OPEN));
                g.draw(new Arc2D.Double(x2-r,y2-r,2*r,2*r,(180-b),b,Arc2D.OPEN));
                g.draw(new Arc2D.Double(x3-r,y3-r,2*r,2*r,-180+a,c,Arc2D.OPEN));
                g.setTransform(oldt);
          }
          private Shape getTriangle(double length,double a,double b,double c){
                double x1=0,y1=0,x2,y2,x3,y3;
                x2=x1+length;
                y2=y1;
                x3=(x1+Math.cos(Math.toRadians(-a))*length);
                y3=(y1+Math.sin(Math.toRadians(-a))*length);
                return getTriangle(x1,y1,x2,y2,x3,y3);
            }
            private Shape getTriangle(double x1,double y1,double x2,double y2,double x3,double y3){
                GeneralPath gp=new GeneralPath();
                gp.moveTo(x1,y1);
                gp.lineTo(x2,y2);
                gp.lineTo(x3,y3);
                gp.closePath();
                return gp;
            }

        private void drawArc(Graphics2D g,int x0,int y0,int x1,int y1,int x2,int y2){
                int r = (int)Math.sqrt((x1-x0)*(x1-x0) + (y1-y0)*(y1-y0));
                int x = x0-r;
                int y = y0-r;
                int width = 2*r;
                int height = 2*r;
                int startAngle = (int) (180/Math.PI*Math.atan2(y1-y0, x1-x0));
                int endAngle = -(int) (180/Math.PI*Math.atan2(y2-y0, x2-x0));
                g.drawArc(x, y, width, height, startAngle, endAngle);
        }
        }
        public class TrianglePanel {
          public static void main(String[] a) {
            JFrame window = new JFrame();
            window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            window.setBounds(30, 30, 300, 300);
            window.getContentPane().add(new MyCanvas());
            window.setVisible(true); 
          }
        }

这些图像显示了 SSCCE 的两次不同运行的结果： 在此处输入图像描述

在此处输入图像描述

任何帮助，将不胜感激。

4

1 回答 1

3

问题是您错误地计算了弧的长度，这会使第二个和第三个角度无法始终按照您想要的方式绘制。

import javax.swing.JComponent;
import javax.swing.JFrame;
import java.awt.geom.*;
import java.awt.*;
import java.util.*;

class MyCanvas extends JComponent {
    int a, supb, b, c, length, r;
    double x1, y1, x2, y2, x3, y3;
    Random random = new Random();

    public MyCanvas() {
            a = random.nextInt(80 - 30) + 30;
            supb = random.nextInt(120 - 70) + 100;
            b = 180 - supb;
            c = 180 - a - b;
            length = random.nextInt(150 - 100) + 100;
            x1 = 0;
            y1 = 0;
            r = 20;
            x2 = x1 + length;
            y2 = y1;
            x3 = (x1 + Math.cos(Math.toRadians(-a)) * length);
            y3 = (y1 + Math.sin(Math.toRadians(-a)) * length);
    }

    public void paintComponent(Graphics g2) {
            float dx1, dy1, ang1, dx2, dy2, ang2, ang3;
            Graphics2D g = (Graphics2D) g2;
            AffineTransform oldt = g.getTransform();

            Shape shape = getTriangle(x1, y1, x2, y2, x3, y3);

            Rectangle2D bounds = shape.getBounds2D();

            double height = bounds.getHeight();
            double width = bounds.getWidth();
            g.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                            RenderingHints.VALUE_ANTIALIAS_ON);
            g.setStroke(new BasicStroke(2.0f, BasicStroke.CAP_BUTT,
                            BasicStroke.JOIN_BEVEL));
            g.translate((this.getWidth() - width) / 2,
                            (this.getHeight() - height) / 2);
            g.translate(-bounds.getX(), -bounds.getY());

            dy1 = (float) (y3 - y1);
            dx1 = (float) (x3 - x1);
            ang1 = (float) (Math.atan((float)(dy1 / dx1)) * 180 / Math.PI);

            ang1 = (float) Math.abs(ang1);

            dy2 = (float) (y2 - y3);
            dx2 = (float) (x2 - x3);
            ang2 = (float) (Math.atan((float)(dy2 / dx2)) * 180 / Math.PI);

            ang2 = (float) Math.abs(ang2);

    ang3 = (float) (180-ang2-ang1);

            g.setColor(Color.BLACK);
            g.draw(shape);
            g.setColor(Color.RED);
            g.draw(new Arc2D.Double(x1 - r, y1 - r, 2 * r, 2 * r, 0, ang1, Arc2D.OPEN));
            g.setColor(Color.GREEN);
            g.draw(new Arc2D.Double(x2 - r, y2 - r, 2 * r, 2 * r, (180 - ang2), ang2,
                            Arc2D.OPEN));
            g.setColor(Color.RED);
            g.draw(new Arc2D.Double(x3 - r, y3 - r, 2 * r, 2 * r, -180 + a, ang3,
                            Arc2D.OPEN));
            g.setTransform(oldt);
    }

    private Shape getTriangle(double x1, double y1, double x2, double y2,
                    double x3, double y3) {
            GeneralPath gp = new GeneralPath();
            gp.moveTo(x1, y1);
            gp.lineTo(x2, y2);
            gp.lineTo(x3, y3);
            gp.closePath();
            return gp;
    }
}

public class TrianglePanel {
        public static void main(String[] a) {
                JFrame window = new JFrame();
                window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                window.setBounds(30, 30, 300, 300);
                window.getContentPane().add(new MyCanvas());
                window.setVisible(true);
        }
}
于 2013-05-20T16:21:39.387 回答