I am working on a college compsci project and I would like some help with a field of view algorithm. I works mostly, but in some situations the algorithm sees through walls and hilights walls the player should not be able to see.

```
void cMap::los(int x0, int y0, int radius)
{ //Does line of sight from any particular tile
for(int x = 0; x < m_Height; x++) {
for(int y = 0; y < m_Width; y++) {
getTile(x,y)->setVisible(false);
}
}
double xdif = 0;
double ydif = 0;
bool visible = false;
float dist = 0;
for (int x = MAX(x0 - radius,0); x < MIN(x0 + radius, m_Height); x++) { //Loops through x values within view radius
for (int y = MAX(y0 - radius,0); y < MIN(y0 + radius, m_Width); y++) { //Loops through y values within view radius
xdif = pow( (double) x - x0, 2);
ydif = pow( (double) y - y0, 2);
dist = (float) sqrt(xdif + ydif); //Gets the distance between the two points
if (dist <= radius) { //If the tile is within view distance,
visible = line(x0, y0, x, y); //check if it can be seen.
if (visible) { //If it can be seen,
getTile(x,y)->setVisible(true); //Mark that tile as viewable
}
}
}
}
}
bool cMap::line(int x0,int y0,int x1,int y1)
{
bool steep = abs(y1-y0) > abs(x1-x0);
if (steep) {
swap(x0, y0);
swap(x1, y1);
}
if (x0 > x1) {
swap(x0,x1);
swap(y0,y1);
}
int deltax = x1-x0;
int deltay = abs(y1-y0);
int error = deltax/2;
int ystep;
int y = y0;
if (y0 < y1)
ystep = 1;
else
ystep = -1;
for (int x = x0; x < x1; x++) {
if ( steep && getTile(y,x)->isBlocked()) {
getTile(y,x)->setVisible(true);
getTile(y,x)->setDiscovered(true);
return false;
} else if (!steep && getTile(x,y)->isBlocked()) {
getTile(x,y)->setVisible(true);
getTile(x,y)->setDiscovered(true);
return false;
}
error -= deltay;
if (error < 0) {
y = y + ystep;
error = error + deltax;
}
}
return true;
}
```

If anyone could help me make the first blocked tiles visible but stops the rest, I would appreciate it.

thanks, Manderin87