Hit ceiling / floor in PTR_ShootTraverse

prboom2/src/p_map.c

@@ -2274,7 +2274,45 @@ dboolean PTR_ShootTraverse (intercept_t* in)
  // hit line
  // position a bit closer
 
- frac = in->frac - FixedDiv (4*FRACUNIT,attackrange);
+ if (map_format.zdoom)
+ {
+ int side = P_PointOnLineSide(trace.x, trace.y, li);
+ sector_t *sec = side ? li->backsector : li->frontsector;
+
+ z = shootz + FixedMul(aimslope, FixedMul(in->frac, attackrange));
+
+ if (sec && sec->floorheight > z)
+ {
+ fixed_t dist;
+
+ if (sec->floorpic == skyflatnum)
+ return false;
+
+ dist = FixedDiv(sec->floorheight - shootz, aimslope);
+ frac = FixedDiv(dist, attackrange);
+ }
+ else if (sec && sec->ceilingheight < z)
+ {
+ fixed_t dist;
+
+ if (sec->ceilingpic == skyflatnum)
+ return false;
+
+ // TODO: ceiling puffs get pushed down and look off
+ dist = FixedDiv(sec->ceilingheight - shootz, aimslope);
+ frac = FixedDiv(dist, attackrange);
+ }
+ else
+ {
+ frac = in->frac;
+ }
+ }
+ else
+ {
+ frac = in->frac;
+ }
+
+ frac -= FixedDiv(4 * FRACUNIT, attackrange);
  x = trace.x + FixedMul (trace.dx, frac);
  y = trace.y + FixedMul (trace.dy, frac);
  z = shootz + FixedMul (aimslope, FixedMul(frac, attackrange));