code:
for (count = 0 ; count < 100 ; count++)
{
if (flags & PT_ADDLINES)
{
AddLineIntercepts(mapx, mapy);
}
if (flags & PT_ADDTHINGS)
{
AddThingIntercepts(mapx, mapy, btit);
}
if (mapx == xt2 && mapy == yt2)
{
break;
}
// [RH] Handle corner cases properly instead of pretending they don't exist.
switch ((((yintercept >> FRACBITS) == mapy) << 1) | ((xintercept >> FRACBITS) == mapx))
{
case 0: // neither xintercept nor yintercept match!
count = 100; // Stop traversing, because somebody screwed up.
break;
case 1: // xintercept matches
xintercept += xstep;
mapy += mapystep;
break;
case 2: // yintercept matches
yintercept += ystep;
mapx += mapxstep;
break;
case 3: // xintercept and yintercept both match
// The trace is exiting a block through its corner. Not only does the block
// being entered need to be checked (which will happen when this loop
// continues), but the other two blocks adjacent to the corner also need to
// be checked.
if (flags & PT_ADDLINES)
{
AddLineIntercepts(mapx + mapxstep, mapy);
AddLineIntercepts(mapx, mapy + mapystep);
}
if (flags & PT_ADDTHINGS)
{
AddThingIntercepts(mapx + mapxstep, mapy, btit);
AddThingIntercepts(mapx, mapy + mapystep, btit);
}
xintercept += xstep;
yintercept += ystep;
mapx += mapxstep;
mapy += mapystep;
break;
}
}
10-11-09 13:28 
