midpoint1.c

计算机图形学

/* WIN-TC BGI 图形编程模板 */

#include "Conio.h"
#include "graphics.h"
#define closegr closegraph

void initgr(void) /* BGI初始化 */
{
  int gd = DETECT, gm = 0; /* 和gd = VGA,gm = VGAHI是同样效果 */
  registerbgidriver(EGAVGA_driver);/* 注册BGI驱动后可以不需要.BGI文件的支持运行 */
  initgraph(&gd, &gm, "");
}

/*-----------------------------数值微分法生成直线-----------------------------*/
void LineDDA1(int x0,int y0,int x1,int y1,int color)
 /*假定x0<x1,直线斜率m<-1*/
 {
   int y;
   float dy,dx,x,m;
   dx=x1-x0;

   dy=y1-y0;
   m=dx/dy;
   x=x0;
   for(y=y0;y>=y1;y--)
   {
     putpixel((int)(x+0.5),y,color);
     x-=m;
   }
 }

 void LineDDA2(int x0,int y0,int x1,int y1,int color)
 /*假定x0<x1,直线斜率-1<=m<=1*/
 {
   int x;
   float dy,dx,y,m;
   dx=x1-x0;
   dy=y1-y0;
   m=dy/dx;
   y=y0;
   for(x=x0;x<=x1;x++)
   {
     putpixel(x,(int)(y+0.5),color);
     y+=m;
   }
 }

 void LineDDA3(int x0,int y0,int x1,int y1,int color)
 /*假定x0<x1,直线斜率m>1*/
 {
   int y;
   float dy,dx,x,m;
   dx=x1-x0;
   dy=y1-y0;
   m=dx/dy;
   x=x0;
   for(y=y0;y<=y1;y++)
   {
     putpixel((int)(x+0.5),y,color);
     x+=m;
   }
 }

/*----------------------------中点算法生成直线--------------------------------*/
 void MidPointLine1(int x0,int y0,int x1,int y1,int color)
{ /*假定x0<x1,直线斜率m<-1*/

int dx,dy,incrE,incrNE,d,x,y;
  dx=x1-x0;
  dy=y1-y0;
  d=-2*dx-dy;
  incrE=-2*dx;
  incrNE=-2*(dx+dy);
  x=x0;y=y0;
  putpixel(x,y,color);
  while(y>=y1)
  {if(d>0)
  d+=incrE;
  else
  { d+=incrNE;
   x++;
  }
  y--;
  putpixel(x,y,color);
  }
}
 void MidPointLine2(int x0,int y0,int x1,int y1,int color)
{ /*假定x0<x1,直线斜率-1<m<0*/

int dx,dy,incrE,incrNE,d,x,y;
  dx=x1-x0;
  dy=y1-y0;
  d=-(dx+2*dy);
  incrE=-2*dy;
  incrNE=-2*(dx+dy);
  x=x0;y=y0;
  putpixel(x,y,color);
  while(x<x1)
  {if(d<=0)
  d+=incrE;
  else
  { d+=incrNE;
  y--;
  }
  x++;
  putpixel(x,y,color);
  }
}
void MidPointLine3(int x0,int y0,int x1,int y1,int color)
{  /* 假定 x0<x1,直线斜率0<=m<=1  */
  int dx,dy,incrE,incrNE,d,x,y;
  dx=x1-x0;
  dy=y1-y0;
  d=dx-2*dy;
  incrE=-2*dy;
  incrNE=2*(dx-dy);
  x=x0;y=y0;
  putpixel(x,y,color);
  while(x<x1)
  {
      if(d>0) d+=incrE;
      else
      {d+=incrNE;
       y++;}
      x++;
  putpixel(x,y,color);
  }
 }
void MidPointLine4(int x0,int y0,int x1,int y1,int color)
{ /*假定x0<x1,直线斜率m>1*/

int dx,dy,incrE,incrNE,d,x,y;
  dx=x1-x0;
  dy=y1-y0;
  d=2*dx-dy;
  incrE=2*dx;
  incrNE=2*(dx-dy);
  x=x0;y=y0;
  putpixel(x,y,color);
  while(x<x1)
  {if(d<=0)
  d+=incrE;
  else
  { d+=incrNE;
  x++;
  }
  y++;
  putpixel(x,y,color);
  }
}
/*-------------------------Bresenham算法生成直线-----------------------------*/
 BresenhamLine(int x0,int y0,int x1,int y1,int color)
{

  int x,y,dx,dy,i;
  float m,d;
  dx=x1-x0;
  dy=y1-y0;
  m=dy/dx;
  d=0;x=x0;y=y0;
  putpixel(x,y,color);
  for(i=0;i<=dx;i++)
  {
    d+=m;
    if(d>=0.5)
     {y+=1;d-=1;}
     x++;
     putpixel(x,y,color);
  }
}
/*-------------------------------建立坐标系----------------------------------*/
void LineH(int x0,int x1,int y0,int color)
 {
   int x,y;
   x=x0; y=y0;
   while(x<x1)
   {putpixel(x,y,color);
    x++;}
 }
void LineV(int y0,int y1,int x0,int color)
 {
   int x,y;
   x=x0; y=y0;
   while(y<y1)
   {putpixel(x,y,color);
    y++;}
 }


 int x0,y0,x1,y1,color,dx1,dy1;
 float m;

int main(void)
{
  initgr(); /* BGI初始化 */

  /*****此部分添加你自己的代码，例如
  line(25, 25, 220, 220);
  circle(100, 100, 50);
  等等*****/


/*-------------------------显示各种斜率的直线--------------------------------*/
  MidPointLine1(300,400,340,240,125);
  MidPointLine2(240,340,400,300,255);
  MidPointLine3(240,300,400,340,255);
  MidPointLine4(300,240,340,400,255);
  LineH(240,400,320,255);
  LineV(240,400,320,255);
  outtextxy(398,318,">");
  outtextxy(280,420,"MidPointLine");
  LineDDA1(180,280,220,120,125);
  LineDDA2(120,220,280,180,255);
  LineDDA2(120,180,280,220,255);
  LineDDA3(180,120,220,280,255);
  LineH(120,280,200,255);
  LineV(120,280,200,255);
  outtextxy(180,300,"LineDDA");

  BresenhamLine(322,53,430,182,255);
  outtextxy(330,160,"Bresenham");
/*----------------------------程序输入部分-----------------------------------*/
  printf("firstpoint x0,y0:\n");
  scanf("%d,%d",&x0,&y0);
  printf("lastpoint x1,y1:\n");
  scanf("%d,%d",&x1,&y1);
  printf("color:\n");
  scanf("%d",&color);
  dx1=x1-x0;
  dy1=y1-y0;
  m=dy1/dx1;
  if(m<-1)
      MidPointLine1(x0,y0,x1,y1,color);
  else if(m>=-1&&m<0)
      MidPointLine2(x0,y0,x1,y1,color) ;
   else if(m>=0&&m<=1)
         MidPointLine3(x0,y0,x1,y1,color) ;
         else
          MidPointLine4(x0,y0,x1,y1,color) ;
  getch(); /* 暂停一下，看看前面绘图代码的运行结果 */
  closegr(); /* 恢复TEXT屏幕模式 */
  return 0;
}