中点画线算法.txt

中点画线算法

#include <stdio.h>
#include <graphics.h>
#include <math.h>

int max(int a,int b)
{
    if(a>b)
        return a;
    else
        return b;

}
int min(int a,int b)
    {

    if(a<b)
        return a;
    else
        return b;

    }
void DDA(int xs,int ys,int xe,int ye,int color)
{

    float dx,dy,k,y,x;
    dx = xe - xs;
    dy = ye - ys;
    if(dx == 0)
    {
        y = min(ys,ye);
        x = xs;
        while(y < max(ys,ye))
        {

            putpixel((int)x,(int)y,color);
            y = y + 1;
            delay(10000);
        }
    }
    else
    {
        k = dy/dx;
        if(fabs(k)<=1)
        {
            x = min(xs,xe);
            if(x == xs)
                y = ys;
            else
                y = ye;
            for(;x < max(xe,xs);x++)
            {
                putpixel((int)x,(int)(y+0.5),color);
                y = y + k;
                delay(10000);
            }
        }
        else
        {    y = min(ys,ye);
             if(y == ys)
                x = xs;
             else
                x = xe;
            for(;y<max(ys,ye);y++)
            {
                putpixel((int)(x+0.5),(int)y,color);
                x = x + 1/k;
                delay(10000);
            }
        }

    }
}
void MidPointLine(int xs,int ys,int xe,int ye ,int color)
{

    float delta1,delta2,d,x,y;
    float k,a,b;
    a = ys - ye;
    b = xe - xs;
    if(b == 0)
    {
        y = min(ys,ye);
        x = xs;
        while(y<max(ys,ye))
        {
            putpixel(x,y,color);
            y++;
        }
    }
    else if(a == 0)
    {
        x = min(xs,xe);
        y = ys;
        while(x<max(xs,xe))
        {
            putpixel(x,y,color);
            x++;
        }
    }
    else
    {
    k = -a/b;
    if(k<1&&k>0)
    {
        x = min(xs,xe);
        if((int)x == xs)
            y = ys;
        else
        {
            y = ye;
            a = -a;
            b = -b;
        }
        delta1 = 2*a;
        delta2 = 2*(a + b);
        d = 2*a + b;
        putpixel(x,y,color);
        while(x < max(xs,xe))
        {
            if(d<=0)
            {
                x++;
                y++;
                d = d+delta2;
            }
            else
            {
                x++;
                d=d+delta1;
            }
            putpixel(x,y,color);
        }
    }
    else if(k>=1)
    {
        y = min(ys,ye);
        if((int)y == ys)
        {
            x = xs;
        }
        else
        {
            x = xe;
            a = -a;
            b = -b;
        }
        delta1 = 2*b;
        delta2 = 2*(a + b);
        d = 2*b + a;
        putpixel(x,y,color);
        while(y < max(ys,ye))
        {
            if(d>0)
            {
                x++;
                y++;
                d = d+delta2;
            }
            else
            {
                y++;
                d=d+delta1;
            }
            putpixel(x,y,color);

        }   
    }
    else if(k<=-1)
    {

        y = min(ys,ye);
        if((int)y == ys)
            x = xs;
        else
        {
            x = xe;
            a = -a;
            b = -b;
        }
        delta1 = 2*b;
        delta2 = 2*(b - a);
        d = 2*b - a;
        putpixel(x,y,color);
        while(y < max(ys,ye))
        {
            if(d<0)
            {
                y++;
                d = d+delta2;
            }
            else
            {
                y++;
                x--;
                d=d+delta1;
            }
            putpixel(x,y,color);
        }   
    }
    else
    {

        x = min(xs,xe);
        y = ys;
        if((int)x == xs)
            y = ys;
        else
        {
            y = ye;
            a = -a;
            b = -b;
        }
        delta1 = 2*a;
        delta2 = 2*(a - b);
        d = 2*a - b;
        putpixel(x,y,color);
        while(x < max(xs,xe))
        {
            if(d<=0)
            {
                x++;
                d = d+delta1;
            }
            else
            {
                x++;
                y--;
                d=d+delta2;
            }
            putpixel(x,y,color);
        }      
    }
    }
}


int BresenhamLine (int xs,int ys,int xe, int ye,int color)

{ int x, y, i,state;
  float k, d,dx, dy;
   dx = xe-xs;
  dy = ye- ys;
  d = 0;
  if(dx == 0)
  {
    y = min(ys,ye);
    x = xs;
    for(i = 0;i < fabs(dy); i++)
    {
        putpixel(x,y,color);
        y++;
    }
    return 1;
  }
  if(dy == 0)
  {
    x = min(xs,xe);
    y = ys;
    while(x < max(xs,xe))
    {
        putpixel(x,y,color);
        x++;
    }
    return 1;
  }
  k = dy/dx;
  if(k<=1&&k>0)
  {
    state = 1;
  }
  else if(k>1)
  {
    state = 2;
  }
  else if(k>=-1&&k<0)
  {
    state = 3;
  }
  else if(k<-1)
  {
    state = 4 ;
  }
  switch(state)
  {
  case 1:
    x=min(xs,xe);
    if(x == xs)
        y = ys;
    else
        y = ye;
    for (i=0; i<=fabs(dx); i++)

    {

        d=d+k;

        if(d>=0.5)
        {
            y++;
            d =d - 1;
        }
        x=x+1;
        putpixel(x, y, color);

    }
    break;
  case 2:

    y = min(ys,ye);
    if(y == ys)
        x = xs;
    else
        x = xe;
    for(i = 0;i<fabs(dy);i++)
    {
        d = d + 1/k;
        if(d>=0.5)
        {
            x++;
            d = d -1;
        }
        y++;
        putpixel(x,y,color);
    }
     break;
  case 3:
    x = min(xs,xe);
    if(x == xs)
        y = ys;
    else
        y = ye;
    for(i=0;i<fabs(dx);i++)
    {
        d = d +k;
        if(d <= -0.5)
        {
            y--;
            d = d+1;
        }
        x++;
        putpixel(x,y,color);

    }
    break;
  case 4:

    y = min(ys,ye);
    if(y ==ys)
    {
        x = xs;
    }
    else
        x = xe;
    for(i = 0;i<fabs(dy);i++)
    {
        d = d + 1/k;
        y++;
        if(d<=-0.5)
        {
            x--;
            d = d+1;
        }
        putpixel(x,y,color);
    }
    break;
  }
  return 1;
}

int main()
{
    int driver = DETECT,graphmode,c;
    printf("choice:1 for DDA,2 for MinPointLine,3 for BresenhamLine\n");
    scanf("%d",&c);
    initgraph(&driver,&graphmode,"c:\\TC");
    setbkcolor(BLACK);
    if(c == 1)
    {
        DDA(320,240,400,80,GREEN) ;

        DDA(320,240,480,160,GREEN) ;

        DDA(320,240,480,320,GREEN) ;

        DDA(320,240,400,400,GREEN) ;

        DDA(320,240,240,400,GREEN) ;

        DDA(320,240,160,320,GREEN) ;

        DDA(320,240,160,160,GREEN) ;

        DDA(320,240,240,80,GREEN) ;

        DDA(160,240,480,240,GREEN) ;

        DDA(320,80,320,400,GREEN) ;

    }
    else if(c == 2)
    {
    MidPointLine(320,240,400,80,GREEN) ;
    MidPointLine(320,240,480,160,GREEN) ;
    MidPointLine(320,240,480,320,GREEN) ;
    MidPointLine(320,240,400,400,GREEN) ;
    MidPointLine(320,240,240,400,GREEN) ;
    MidPointLine(320,240,160,320,GREEN) ;
    MidPointLine(320,240,160,160,GREEN) ;
    MidPointLine(320,240,240,80,GREEN) ;
    MidPointLine(480,240,160,240,GREEN) ;
    MidPointLine(320,80,320,400,GREEN) ;
    }
    else if(c == 3)
    {
        BresenhamLine(320,240,400,80,GREEN) ;
        BresenhamLine(320,240,480,160,GREEN) ;
        BresenhamLine(320,240,480,320,GREEN) ;
        BresenhamLine(320,240,400,400,GREEN) ;
        BresenhamLine(320,240,240,400,GREEN) ;
        BresenhamLine(320,240,160,320,GREEN) ;
        BresenhamLine(320,240,160,160,GREEN) ;
        BresenhamLine(320,240,240,80,GREEN) ;
        BresenhamLine(480,240,160,240,GREEN) ;
        BresenhamLine(320,80,320,400,GREEN) ;
    }


    getch();
    closegraph();
}