void drawline2d(int x0, int y0, int x1, int y1, int color)
{
int i;
int steep = 1;
int sx, sy; /* step positive or negative (1 or -1) */
int dx, dy; /* delta (difference in X and Y between points) */
int e;
/*
* inline swap. On some architectures, the XOR trick may be faster
*/
int tmpswap;
#define SWAP(a,b) tmpswap = a; a = b; b = tmpswap;
/*
* optimize for vertical and horizontal lines here
*/
dx = abs(x1 - x0);
sx = ((x1 - x0) > 0) ? 1 : -1;
dy = abs(y1 - y0);
sy = ((y1 - y0) > 0) ? 1 : -1;
if (dy > dx) {
steep = 0;
SWAP(x0, y0);
SWAP(dx, dy);
SWAP(sx, sy);
}
e = (dy << 1) - dx;
for (i = 0; i < dx; i++) {
if (steep) {
plot(x0,y0,color);
} else {
plot(y0,x0,color);
}
while (e >= 0) {
y0 += sy;
e -= (dx << 1);
}
x0 += sx;
e += (dy << 1);
}
}