From 50ce152c69fa11faef84cb51f215d787852d4742 Mon Sep 17 00:00:00 2001
From: toasterbabe <rollerorbital@gmail.com>
Date: Sun, 28 Aug 2016 13:19:17 +0100
Subject: [PATCH] Cleaned up some performance issues in Skytop Zone (2.1.16:
 THE SUGOI UPDATE) arising from some inefficiencies with P_GetMobjGravity. FPS
 drops only occasionally to 34 now, which is a big improvement when I was
 frequently getting 27 in Salt's 15andahalf.exe.

---
 src/p_mobj.c | 57 +++++++++++++++++++++-------------------------------
 1 file changed, 23 insertions(+), 34 deletions(-)

diff --git a/src/p_mobj.c b/src/p_mobj.c
index 62dee0a6..91451e06 100644
--- a/src/p_mobj.c
+++ b/src/p_mobj.c
@@ -1278,25 +1278,23 @@ fixed_t P_GetMobjGravity(mobj_t *mo)
 
 		for (rover = mo->subsector->sector->ffloors; rover; rover = rover->next)
 		{
-			if (!(rover->flags & FF_EXISTS))
+			if (!((rover->flags & FF_EXISTS) && (P_InsideANonSolidFFloor(mo, rover))))
 				continue;
 
-			if (P_InsideANonSolidFFloor(mo, rover))
-			{
-				if ((rover->flags & (FF_SWIMMABLE|FF_GOOWATER)) == (FF_SWIMMABLE|FF_GOOWATER))
-					goopgravity = true;
-				if (rover->master->frontsector->gravity)
-				{
-					gravityadd = -FixedMul(gravity,
-						(FixedDiv(*rover->master->frontsector->gravity>>FRACBITS, 1000)));
+			if ((rover->flags & (FF_SWIMMABLE|FF_GOOWATER)) == (FF_SWIMMABLE|FF_GOOWATER))
+				goopgravity = true;
 
-					if (rover->master->frontsector->verticalflip && gravityadd > 0)
-						mo->eflags |= MFE_VERTICALFLIP;
+			if (!(rover->master->frontsector->gravity))
+				continue;
 
-					no3dfloorgrav = false;
-					break;
-				}
-			}
+			gravityadd = -FixedMul(gravity,
+				(FixedDiv(*rover->master->frontsector->gravity>>FRACBITS, 1000)));
+
+			if (rover->master->frontsector->verticalflip && gravityadd > 0)
+				mo->eflags |= MFE_VERTICALFLIP;
+
+			no3dfloorgrav = false;
+			break;
 		}
 	}
 
@@ -1318,28 +1316,22 @@ fixed_t P_GetMobjGravity(mobj_t *mo)
 
 	if (mo->player)
 	{
-		if (mo->player->charability == CA_FLY && (mo->player->powers[pw_tailsfly]
-		|| (mo->state >= &states[S_PLAY_SPC1] && mo->state <= &states[S_PLAY_SPC4])))
-			gravityadd = gravityadd/3; // less gravity while flying
-		if (mo->player->pflags & PF_GLIDING)
-			gravityadd = gravityadd/3; // less gravity while gliding
-		if (mo->player->climbing)
-			gravityadd = 0;
-		if (mo->player->pflags & PF_NIGHTSMODE)
+		if ((mo->player->pflags & PF_GLIDING)
+		|| (mo->player->charability == CA_FLY && (mo->player->powers[pw_tailsfly]
+			|| (mo->state >= &states[S_PLAY_SPC1] && mo->state <= &states[S_PLAY_SPC4]))))
+			gravityadd = gravityadd/3; // less gravity while flying/gliding
+		if (mo->player->climbing || (mo->player->pflags & PF_NIGHTSMODE))
 			gravityadd = 0;
 
 		{
-			UINT8 bits = 0;
-			if (mo->flags2 & MF2_OBJECTFLIP)
-				bits ^= 1;
-			if (mo->player->powers[pw_gravityboots])
-				bits ^= 1;
-			if (bits & 1)
+			if (!!(mo->flags2 & MF2_OBJECTFLIP) != !!(mo->player->powers[pw_gravityboots]))
 			{
 				gravityadd = -gravityadd;
 				mo->eflags ^= MFE_VERTICALFLIP;
 			}
 		}
+		if (!!(mo->eflags & MFE_VERTICALFLIP) != wasflip)
+			P_PlayerFlip(mo);
 	}
 	else
 	{
@@ -1347,10 +1339,10 @@ fixed_t P_GetMobjGravity(mobj_t *mo)
 		if (mo->flags2 & MF2_OBJECTFLIP)
 		{
 			mo->eflags |= MFE_VERTICALFLIP;
-			if (gravityadd < 0) // Don't sink, only rise up
-				gravityadd *= -1;
 			if (mo->z + mo->height >= mo->ceilingz)
 				gravityadd = 0;
+			else if (gravityadd < 0) // Don't sink, only rise up
+				gravityadd *= -1;
 		}
 		else //Otherwise, sort through the other exceptions.
 		{
@@ -1396,9 +1388,6 @@ fixed_t P_GetMobjGravity(mobj_t *mo)
 	if (goopgravity)
 		gravityadd = -gravityadd/5;
 
-	if (mo->player && !!(mo->eflags & MFE_VERTICALFLIP) != wasflip)
-		P_PlayerFlip(mo);
-
 	gravityadd = FixedMul(gravityadd, mo->scale);
 
 	return gravityadd;