直线的生成算法（三种）

#include <math.h> #include<stdio.h> #include<stdlib.h> #include<graphics.h> void DDALine(int x1, int y1, int x2, int y2, int color) { float increx,increy,x,y,length; int i; if(abs(x2-x1)>abs(y2-y1)) length = abs(x2-x1); else length = abs(y2-y1); increx = (x2-x1)/length; increy = (y2-y1)/length; x = x1; y = y1; for(i=1;i<=length;i++) { putpixel(int(x+0.5),int(y+0.5),color); //在(x，y)处，以color色画点 x += increx; y += increy; } } void cbLine(int x1,int y1,int x2,int y2) { int dx,dy,n,k,i,f; int x,y; dx = abs(x2-x1); dy = abs(y2-y1); n = dx+dy; if(x2>=x1) { k= y2>=y1?1:4; x = x1; y = y1; } else { k = y2>=y1? 2:3; x = x1; y = y1; } putpixel(x,y,4); for(i=0,f=0;i<n;i++) if(f>= 0) switch(k) { case 1:putpixel(x++,y,4);f -= dy;break; case 2:putpixel(x,y++,4);f -= dx;break; case 3:putpixel(x--,y,4);f -= dy;break; case 4:putpixel(x,y--,4);f -= dx;break; } else switch(k) { case 1:putpixel(x,y++,4);f += dx;break; case 2:putpixel(x--,y,4);f += dy;break; case 3:putpixel(x,y--,4);f += dx;break; case 4:putpixel(x++,y,4);f += dy;break; } } int sign(int a) { if(a>0) return 1; else if(a==0) return 0; else return -1; } void BresenhamLine(int x1,int y1,int x2,int y2,int color) { int x,y,s1,s2,increx,increy,temp,interchange; int e,i; x = x1; y = y1; s1 = sign(x2-x1); s2 = sign(y2-y1); increx = abs(x2-x1); increy = abs(y2-y1); if(increy > increx) { temp = increx; increx = increy; increy = temp; interchange = 1; } else interchange = 0; e = 2*increy-increx; for(i=1;i<=increx;i++) { putpixel(x,y,color); if(e>=0) { if(interchange = 1) x = x+s1; else y = y+s2; e = e-2*increx; } if(interchange = 1) y = y+s2; else x = x+s1; e = e+2*increy; } } main() { /* *1.--------紫色线条：DDA算法--------- *2.--------红色线条：逐点比较算法--------- *3.--------绿色线条：Bresenham算法--------- */ int mode,driver; mode = VGA; mode = VGAMED; initgraph(&driver,&mode," "); cleardevice(); DDALine(10,40,100,300,5); cbLine(30,50,200,400); BresenhamLine(100,50,400,400,2); getch(); closegraph(); }