C
Just tracing the ray. When it splits, recurse one way and continue the other. Didn't bother with a direction lookup table this time, just a few ifs. The ray ends when it goes out of bounds or a ray in that direction has been previously traced on a given cell (this is tracked with a separate table).
It would've been straightforward if I hadn't gotten the 'previously visited' check wrong ๐. I was checking against the direction coming in of the tile but marking the direction going out.
Ray function:
static void
ray(int x, int y, int dir)
{
int c;
while (x>=0 && y>=0 && x<w && y<h) {
if (beams[y][x] & (1 << dir))
break;
beams[y][x] |= 1 << dir;
c = map[y][x];
if (dir==NN && c=='/') dir = EE; else
if (dir==EE && c=='/') dir = NN; else
if (dir==SS && c=='/') dir = WW; else
if (dir==WW && c=='/') dir = SS; else
if (dir==NN && c=='\\') dir = WW; else
if (dir==EE && c=='\\') dir = SS; else
if (dir==SS && c=='\\') dir = EE; else
if (dir==WW && c=='\\') dir = NN; else
if (dir==NN && c=='-') { ray(x,y,WW); dir = EE; } else
if (dir==SS && c=='-') { ray(x,y,WW); dir = EE; } else
if (dir==EE && c=='|') { ray(x,y,NN); dir = SS; } else
if (dir==WW && c=='|') { ray(x,y,NN); dir = SS; }
x += dir==EE ? 1 : dir==WW ? -1 : 0;
y += dir==SS ? 1 : dir==NN ? -1 : 0;
}
}