From 51553e7f75442c74e1aefa1ba0f9fd94f735f919 Mon Sep 17 00:00:00 2001
From: Eidolon <furyhunter600@gmail.com>
Date: Wed, 27 Apr 2022 21:39:47 -0500
Subject: [PATCH] Interpolate mobj scale

---
 src/hardware/hw_main.c | 2 +-
 src/p_mobj.h           | 2 ++
 src/r_fps.c            | 3 +++
 src/r_fps.h            | 1 +
 src/r_things.c         | 4 +++-
 5 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/hardware/hw_main.c b/src/hardware/hw_main.c
index 747d3402b..013f60ed4 100644
--- a/src/hardware/hw_main.c
+++ b/src/hardware/hw_main.c
@@ -5112,7 +5112,7 @@ static void HWR_ProjectSprite(mobj_t *thing)
 		R_InterpolateMobjState(thing, FRACUNIT, &interp);
 	}
 
-	this_scale = FIXED_TO_FLOAT(thing->scale);
+	this_scale = FIXED_TO_FLOAT(interp.scale);
 	spritexscale = FIXED_TO_FLOAT(thing->spritexscale);
 	spriteyscale = FIXED_TO_FLOAT(thing->spriteyscale);
 
diff --git a/src/p_mobj.h b/src/p_mobj.h
index 498eeb8a6..e20920181 100644
--- a/src/p_mobj.h
+++ b/src/p_mobj.h
@@ -377,6 +377,8 @@ typedef struct mobj_s
 	UINT32 mobjnum; // A unique number for this mobj. Used for restoring pointers on save games.
 
 	fixed_t scale;
+	fixed_t old_scale; // interpolation
+	fixed_t old_scale2;
 	fixed_t destscale;
 	fixed_t scalespeed;
 
diff --git a/src/r_fps.c b/src/r_fps.c
index d3a996207..a897ee555 100644
--- a/src/r_fps.c
+++ b/src/r_fps.c
@@ -266,6 +266,7 @@ void R_InterpolateMobjState(mobj_t *mobj, fixed_t frac, interpmobjstate_t *out)
 	out->x = R_LerpFixed(mobj->old_x, mobj->x, frac);
 	out->y = R_LerpFixed(mobj->old_y, mobj->y, frac);
 	out->z = R_LerpFixed(mobj->old_z, mobj->z, frac);
+	out->scale = R_LerpFixed(mobj->old_scale, mobj->scale, frac);
 
 	out->subsector = R_PointInSubsector(out->x, out->y);
 
@@ -704,12 +705,14 @@ void R_ResetMobjInterpolationState(mobj_t *mobj)
 	mobj->old_angle2 = mobj->old_angle;
 	mobj->old_pitch2 = mobj->old_pitch;
 	mobj->old_roll2 = mobj->old_roll;
+	mobj->old_scale2 = mobj->old_scale;
 	mobj->old_x = mobj->x;
 	mobj->old_y = mobj->y;
 	mobj->old_z = mobj->z;
 	mobj->old_angle = mobj->angle;
 	mobj->old_pitch = mobj->pitch;
 	mobj->old_roll = mobj->roll;
+	mobj->old_scale = mobj->scale;
 
 	if (mobj->player)
 	{
diff --git a/src/r_fps.h b/src/r_fps.h
index cf66d72f9..9a2d1d26d 100644
--- a/src/r_fps.h
+++ b/src/r_fps.h
@@ -59,6 +59,7 @@ typedef struct {
 	fixed_t z;
 	subsector_t *subsector;
 	angle_t angle;
+	fixed_t scale;
 } interpmobjstate_t;
 
 // Level interpolators
diff --git a/src/r_things.c b/src/r_things.c
index fa6baddec..32ef455fe 100644
--- a/src/r_things.c
+++ b/src/r_things.c
@@ -1481,7 +1481,7 @@ static void R_ProjectSprite(mobj_t *thing)
 	fixed_t gz = 0, gzt = 0;
 	INT32 heightsec, phs;
 	INT32 light = 0;
-	fixed_t this_scale = thing->scale;
+	fixed_t this_scale;
 	fixed_t spritexscale, spriteyscale;
 
 	// rotsprite
@@ -1506,6 +1506,8 @@ static void R_ProjectSprite(mobj_t *thing)
 		R_InterpolateMobjState(thing, FRACUNIT, &interp);
 	}
 
+	this_scale = interp.scale;
+
 	// transform the origin point
 	tr_x = interp.x - viewx;
 	tr_y = interp.y - viewy;