Java and matlab drawing polygon closure polyline diagram example

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1. Use matlab for closed polygon diagram

No function was found to draw the polygon directly, except to save the coordinates of each point in an array, connect a point to its neighbor, and connect the last point to the first point. Here is a sample. M file:

clear;
clc;
a=[0 2 4 6 8 10 12 14;0 2 1 4 6 6 5 7];  % The coordinates of the points to connect  x;y
[n,m]=size(a);
for i=1:m-1;
    line([a(1,i),a(1,i+1)],[a(2,i),a(2,i+1)]);  % Connect the nodes line([x1,x2],[y1,y2])
    hold on
end
hold on
line([a(1,1),a(1,m)],[a(2,1),a(2,m)]);  % The head and tail nodes are connected 

  2. Use Java to make closed polygon diagrams

The Graphics class drawPolygon function in Java provides direct polygon plotting.

Function prototype: public abstract void drawPolygon(int[] xPoints, int[] yPoints,int nPoints)

instructions

(1) draws a closed polygon defined by an array of x and y coordinates. Each pair of (x, y) coordinates defines a point. NPoints is the number of line segments.

(2) the preceding npoint-1 line segment is the line segment from (xPoints[I -1], yPoints[I -1]) to (xPoints[I], yPoints[I]) when 1 Or less I Or less nPoints. If the last point is different from the first, the graph closes automatically by drawing a line segment between the two points.

The code example is as follows:

import java.applet.*;
import java.awt.*;
public class DrawPicture extends Applet 
{   public void paint(Graphics g)
    { 
      int px[]={20,70,130,240};
      int py[]={20,150,100,130};
      g.drawPolygon(px,py,4); 
    }      
}

3. The instructions

Whether a polygon can be formed, convex, or concave depends on the order of the points given.

The program is only responsible for connecting adjacent nodes, and connecting head to tail.