直线DDA，直线和圆的Bresenham算法

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// DDA.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include<Windows.h>
#include<graphics.h>
#include<conio.h>
#include<math.h>
void dda_line(int xa,int ya,int xb,int yb,int c);
int main(int argc,_TCHAR* argv[])
{
    int gd=DETECT,gm; /*图形屏幕初始化*/
    initgraph(&gd,&gm,"");
    dda_line(100,100,200,255);
    getch();
    closegraph();
    return 0;
}


void dda_line(int xa,int c)
{
float delta_x,delta_y,x,y;
int dx,dy,steps,k;
dx=xb-xa;
dy=yb-ya;
if(abs(dx)>abs(dy))steps=abs(dx);
else steps=abs(dy);
delta_x=(float)dx/(float)steps;
delta_y=(float)dy/(float)steps;
x=xa;
y=ya;
putpixel(x,y,c);
for(k=1;k<=steps;k++)
{
x+=delta_x;
y+=delta_y;
putpixel(x,c);
}
}

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#include "stdafx.h"
#include<Windows.h>
#include<graphics.h>
#include<conio.h>
#include<math.h>
void lineBres(int x0,int y0,int xEnd,int yEnd,"");
    lineBres(0,0,255);
    getch();
    closegraph();
    return 0;
}


void lineBres(int x0,int c)
{
        int dx = (int)fabs(double((xEnd-x0)));
        int dy = (int)fabs(double(yEnd-y0));
        int p =2* dy-dx;
        int twoDy = 2*dy,twoDyMinusDx = 2* (dy - dx);
        int x,y;

        if (x0>xEnd)
        {
                x=xEnd;
                y=yEnd;
                xEnd=x0;
        }
        else{
                x=x0;
                y=y0;
        }
        putpixel (x,c);

        while (x<xEnd)
        {
                x++;
                if(p<0)
                        p+=twoDy;
                else{
                        y++;
                        p+=twoDyMinusDx;
                }
               putpixel (x,c);
       }
}

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#include "stdafx.h"
#include<Windows.h>
#include<graphics.h>
#include<conio.h>
#include<math.h>
void CircleBres(int xc,int yc,int radious,int c);
void plot_circle_points(int xc,int x,int y,"");
    CircleBres(100,20,255);
    getch();
    closegraph();
    return 0;
}
void CircleBres(int xc,int c)
{
     int x,p;
     x=0;
     y=radious;
     p=3-2*radious;
     while(x<y){
         plot_circle_points(xc,yc,c);
         if(p<0) p=p+4*x+6;
         else{
         p=p+4*(x-y)+10;
         y-=1;
         } 
     x+=1;
     }
     if(x==y){
         plot_circle_points(xc,c);
     }
}
void plot_circle_points(int xc,int c)
{
    putpixel(xc+x,yc+y,c);
    putpixel(xc-x,c);
    putpixel(xc+x,yc-y,c);
    putpixel(xc+y,yc+x,c);
    putpixel(xc-y,yc-x,c);
}

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