Question

利用C语言编写 能够画出任意的直线算法程序（利用画点函数）

利用C语言编写 能够画出任意斜率的直线算法程序（利用画点函数）

Answer 1

上次刚写过，在VC下运行的，
int dx,dy,incrE,incrNE,d,x,y;

if ((point[1].x-point[0].x)==0){ //垂直的直线
x=point[0].x;
for(y=point[0].y;y<point[1].y;y++)
pDC->SetPixel(x,y,50);
}
else if(abs((point[1].y-point[0].y)/(point[1].x-point[0].x))<=1){ //斜率 -1到 1 之间
dx=point[1].x-point[0].x;
dy=point[0].y-point[1].y;
d=dx-2*dy;

incrE=-2*dy;
incrNE=2*(dx-dy);
x=point[0].x,y=point[0].y;
pDC->SetPixel(x,y,50);
if(point[0].y>point[1].y){
while(x<point[1].x)
{
if(d>=0){
d+=incrE;
x++;
}
else
{d+=incrNE;
x++;
y--;
}
pDC->SetPixel(x,y,50);
}
}
else if(point[0].y<=point[1].y){
dy=point[1].y-point[0].y;
incrE=-2*dy;
incrNE=2*(dx-dy);
x=point[0].x,y=point[0].y;
pDC->SetPixel(x,y,50);
while(x<point[1].x)
{
if(d>=0){
d+=incrE;
x++;
}
else
{d+=incrNE;
x++;
y++;
}
pDC->SetPixel(x,y,50);
}
}
}
else { //斜率 <-1 和 >1的直线
if(point[1].x>=point[0].x){
dx=point[1].x-point[0].x;
dy=point[1].y-point[0].y;
d=2*dx-dy;
incrE=2*dx;
incrNE=2*(dx-dy);
x=point[0].x,y=point[0].y;
pDC->SetPixel(x,y,50);
while(x<point[1].x)
{
if(d<0){
d+=incrE;

y++;

}
else
{d+=incrNE;
pDC->SetPixel(x,y,50);
x++;
y++;
}
pDC->SetPixel(x,y,50);
}
}
else if((point[1].y-point[0].y)/(point[1].x-point[0].x)<-1){
dx=point[1].x-point[0].x;
dy=point[0].y-point[1].y;
d=2*dx-dy;
incrE=2*dx;
incrNE=2*(dx-dy);
x=point[0].x,y=point[0].y;
pDC->SetPixel(x,y,50);
while(y<point[1].y)
{
if(d>0){
d+=incrE;
y++;

}
else
{d+=incrNE;
x--;
y++;
}
pDC->SetPixel(x,y,50);
}

}

}