计算机图形学-边界标志算法-java实现

import javax.swing.JFrame;

public class BoundaryColor {
TwoDimen env;
public static void main(String args[]) {
new BoundaryColor();
}

public BoundaryColor() {
// A(3,15)B(18,30)C(33,15)D(15,3)
// AB BC CD DA
JFrame frame = new JFrame();
env = new TwoDimen();
frame.getContentPane().add(env);
frame.setBounds(100, 100, 600, 600);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setResizable(false);
frame.setVisible(true);
int[] X = new int[] { 3, 18, 33, 15, 3 };
int[] Y = new int[] { 15, 30, 15, 3, 15 };
int i = 0;
double x, y;
double dy, dx;
int ymin, ymax;
for (i = 0; i < X.length - 1; i++) {
//System.out.println(i);
dy = Y[i + 1] - Y[i];
if (dy != 0) {
dx = (X[i + 1] - X[i]) / dy;
if (dy > 0)
x = X[i];
else
x = X[i + 1];
if (Y[i] >= Y[i + 1]) {
ymin = Y[i + 1];
ymax = Y[i];
} else {
ymin = Y[i];
ymax = Y[i + 1];
}
/*for (y = ymin; y <= ymax - 1; y++) {
x = x + dx;
if (env.isFlag((int) x, (int) y)) {
env.setFlag((int) (x + 1), (int) y);
} else {
env.setFlag((int) x, (int) y);
}
}*/
int k,j;
k=Math.abs(X[i+1]-X[i]);
if(Math.abs(Y[i+1]-Y[i])>k)k=Math.abs(Y[i+1]-Y[i]);
dx=(float)(X[i+1]-X[i])/k;
dy=(float)(Y[i+1]-Y[i])/k;
x=(float)(X[i]);
y=(float)(Y[i]);
for(j=0;j<k;j++){
if (env.isFlag((int) (x+0.5), (int) (y+0.5))) {
env.setFlag((int) (x + 1.5), (int) (y+0.5));
} else {
env.setFlag((int) (x+0.5), (int) (y+0.5));
}
x=x+dx;
y=y+dy;
}
}
}

// ************************************
double maxx, maxy, minx, miny;
double x1, y1;
int in_flag = 0;
minx = X[0];
maxx = X[2];
miny = Y[3];
maxy = Y[1];
for (y1 = miny - 1; y1 <= maxy - 1; y1++) {
in_flag = 0;
for (x1 = minx - 1; x1 <= maxx - 1; x1++) {
if (env.isFlag((int) x1, (int) y1)) {
if (in_flag==0)
in_flag=1;
else
in_flag=0;
}
if(in_flag!=0)
env.drawPoint((int)x1,(int)y1);
else
env.cleanPoint((int)x1,(int)y1);
}
}
}
}