用Bresenham算法绘制多边形的算法

Posted 2023-04-02

敬请回复，谢谢！

参考技术A void SetPixel( int x, int y )

glBegin( GL_POINTS );

glColor3f(
(double)( y + alpha * 10 ) / ( height + alpha * 10 ),
(double)( x + y ) / ( width + height ),
(double)( x + alpha * 10 ) / ( height + alpha * 10 )
);
glVertex2i( x, y );

glEnd( );


// Bresenham line algorithm
void MyLine( int xs, int ys, int xe, int ye )

// Write your code here
int dx, dy, x, y, p, k;
dx = abs( xe - xs );
dy = abs( ye - ys );
k = ( xe - xs ) * ( ye - ys );

if ( dx >= dy )

p = 2 * dy - dx;
if ( xs < xe ) x = xs; y = ys;

else y = ye; x = xe; xe = xs;


while ( x < xe )
SetPixel( x, y );
++x;
if ( p < 0 )
p += 2 * dy;
else
if ( k > 0 ) ++y;
else --y;
p += 2 * dy - 2 * dx;



else

p = 2 * dx - dy;
if ( ys < ye ) x = xs; y = ys;

else y = ye; x = xe; ye = ys;


while ( y < ye )
SetPixel( x, y );
++y;
if ( p < 0 )
p += 2 * dx;
else
if ( k > 0 ) ++x;
else --x;
p += 2 * dx - 2 * dy;




Bresenham算法是划线段的，多画几条就成多边形了。
MyLine四个参数分别是起止点的x y坐标。本回答被提问者采纳

Bresenham 线算法错误

【中文标题】Bresenham 线算法错误

【英文标题】：Error with Bresenham's line algorithm

【发布时间】：2015-08-28 19:24:01

【问题描述】：

我正在尝试用星号 (*) 填充矩阵以绘制 Bresenham 的线，但是当我打印出矩阵仅填充一颗星的东西时，我不知道出了什么问题。语言是Java

public class PtLine extends VectorObject   // inherites from another class
private int bx;
private int by;
private int delX;
private int delY;

public PtLine(int id,int x,int y,int bx,int by)
     super(id,x,y);
     this.bx = bx;
     this.by = by;
     this.delX = this.bx-x;
     this.delY = this.by-y;

 
 public void draw ( char [][] matrix )    // filling the martic with stars
    int D = 2*delY - delX;
    matrix[x][y] = '*';
    int j = y;

    for (int i=x+1;i==bx;i++)
       if(D > 0)
          j+=1;
          matrix[i][j]='*';
          D = D + (2*delY-2*delX);
       
      else
         matrix[i][j]='*';
         D = D + (2*delY);
       
     
      

下面的代码是当我试图打印出矩阵时

  class Question3
     public static void main ( String args [] )


     char[][] matrix = new char[20][20];
     for (int y = 0; y < 20; y++) 
        for (int x = 0; x < 20; x++) 
            matrix[y][x] = ' ';
         
      

     PtLine n = new PtLine(6,6,6,13,13);
     n.draw(matrix);
     for (int y = 0; y < 20; y++) 
        for (int x = 0; x < 20; x++) 
            System.out.print(matrix[x][y]);
         
         System.out.println();
      
 

【参考方案1】：

您可能必须将i==bx 更改为i!=bx：

public void draw ( char [][] matrix )    // filling the martic with stars
  int D = 2*delY - delX;
  matrix[x][y] = '*';
  int j = y;

  for (int i=x+1;i!=bx;i++) // here
  ...
  

for 循环在此条件为真时继续。在您的代码循环中，在第一次迭代之前立即结束，因为这个条件是假的。