计算机图形学基础（1）——画线算法

画线算法

• DDA（数值微分法）

void DDALine(int x0,int y0,int x1,int y1){    float delta,x,y,dx,dy;    dx = x1-x0;    dy = y1-y0;    delta = dy/dx;    y = y0;    x = x0;    if(delta>=1){   //斜率大于等于1         for(y=y0;y<=y1;y++){            DrawPixel(int(x+0.5),y);            x+=1./delta;        }    }    else    for(x=x0;x<=x1;x++){    //斜率小于1         DrawPixel(x,int(y+0.5));        y+=delta;    }}

• 中点画线法

 void MidPointLine(int x0,int y0,int x1,int y1){    int a,b,x,y,d,delta1,delta2,k;    a = y0-y1;    b = x1-x0;    x = x0;    y = y0;    k = (y1-y0)>=(x1-x0)?-1:1;    DrawPixel(x,y);    if(k==1){        //斜率为0~1        delta1 = 2*a;        delta2 = 2*(a+b);        d = 2*a+b;        while(x<x1){            if(d<0){                x++;                y++;                d+=delta2;            }            else{                x++;                d+=delta1;            }            DrawPixel(x,y);        }    }    else{          //斜率为1~∞        delta1 = 2*b;        delta2 = 2*(a+b);        d = a+2*b;        while(y<y1){            if(d>0){                x++;                y++;                d+=delta2;            }            else{                y++;                d+=delta1;            }            DrawPixel(x,y);        }    }} 

• Bersenham画线算法（e=k-0.5）

void BersenhamLine(int x0,int y0,int x1,int y1){    int x,y,dx,dy,e;    x = x0;    y = y0;    dx = x1-x0;    dy = y1-y0;    e = 2*dy - dx;     //new_e = 2*e*dx,此处代码里出现的均为new_e    while(x<x1){        DrawPixel(x,y);        x++;        e+=2*dy;        if(e>=1){            y++;            e-=2*dx;        }    }} 

没有图，有点无聊，附上喜欢的图：

ps3大神绝景版，水墨渲染厉害了