From ca88db00cdf77055615db7b6cd19e06ca401e3cf Mon Sep 17 00:00:00 2001
From: Snu <coolzach5@gmail.com>
Date: Wed, 30 Sep 2020 07:56:57 +0100
Subject: [PATCH] Create P_CeilingzAtPos function

---
 src/p_local.h |  1 +
 src/p_map.c   | 46 +++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/src/p_local.h b/src/p_local.h
index 9873a20af..525c1a3bd 100644
--- a/src/p_local.h
+++ b/src/p_local.h
@@ -424,6 +424,7 @@ void P_Initsecnode(void);
 void P_RadiusAttack(mobj_t *spot, mobj_t *source, fixed_t damagedist, UINT8 damagetype, boolean sightcheck);
 
 fixed_t P_FloorzAtPos(fixed_t x, fixed_t y, fixed_t z, fixed_t height);
+fixed_t P_CeilingzAtPos(fixed_t x, fixed_t y, fixed_t z, fixed_t height);
 boolean PIT_PushableMoved(mobj_t *thing);
 
 boolean P_DoSpring(mobj_t *spring, mobj_t *object);
diff --git a/src/p_map.c b/src/p_map.c
index b7ad14808..d26b1707d 100644
--- a/src/p_map.c
+++ b/src/p_map.c
@@ -4953,7 +4953,7 @@ void P_MapEnd(void)
 }
 
 // P_FloorzAtPos
-// Returns the floorz of the XYZ position // TODO: Need ceilingpos function too
+// Returns the floorz of the XYZ position
 // Tails 05-26-2003
 fixed_t P_FloorzAtPos(fixed_t x, fixed_t y, fixed_t z, fixed_t height)
 {
@@ -4997,3 +4997,47 @@ fixed_t P_FloorzAtPos(fixed_t x, fixed_t y, fixed_t z, fixed_t height)
 
 	return floorz;
 }
+
+// P_CeilingZAtPos
+// Returns the ceilinz of the XYZ position
+fixed_t P_CeilingzAtPos(fixed_t x, fixed_t y, fixed_t z, fixed_t height)
+{
+	sector_t *sec = R_PointInSubsector(x, y)->sector;
+	fixed_t ceilingz = P_GetSectorCeilingZAt(sec, x, y);
+
+	if (sec->ffloors)
+	{
+		ffloor_t *rover;
+		fixed_t delta1, delta2, thingtop = z + height;
+
+		for (rover = sec->ffloors; rover; rover = rover->next)
+		{
+			fixed_t topheight, bottomheight;
+			if (!(rover->flags & FF_EXISTS))
+				continue;
+
+			if ((!(rover->flags & FF_SOLID || rover->flags & FF_QUICKSAND) || (rover->flags & FF_SWIMMABLE)))
+				continue;
+
+			topheight    = P_GetFFloorTopZAt   (rover, x, y);
+			bottomheight = P_GetFFloorBottomZAt(rover, x, y);
+
+			if (rover->flags & FF_QUICKSAND)
+			{
+				if (z < topheight && bottomheight < thingtop)
+				{
+					if (ceilingz < z)
+						ceilingz = z;
+				}
+				continue;
+			}
+
+			delta1 = z - (bottomheight + ((topheight - bottomheight)/2));
+			delta2 = thingtop - (bottomheight + ((topheight - bottomheight)/2));
+			if (bottomheight > ceilingz && abs(delta1) < abs(delta2))
+				ceilingz = bottomheight;
+		}
+	}
+
+	return ceilingz;
+}
\ No newline at end of file