From 195920acdcffca94bb335bc06d3dea5cd238da43 Mon Sep 17 00:00:00 2001
From: Sryder <sryder13@gmail.com>
Date: Thu, 21 May 2020 17:15:50 +0100
Subject: [PATCH] Update light offset on polyobjects when they rotate

---
 src/p_polyobj.c |  3 +++
 src/p_setup.c   | 31 +++++++++++++++++++++----------
 src/p_setup.h   |  1 +
 3 files changed, 25 insertions(+), 10 deletions(-)

diff --git a/src/p_polyobj.c b/src/p_polyobj.c
index 03fb10d0f..12708a44b 100644
--- a/src/p_polyobj.c
+++ b/src/p_polyobj.c
@@ -1407,7 +1407,10 @@ static boolean Polyobj_rotate(polyobj_t *po, angle_t delta, UINT8 turnthings)
 	{
 		// update seg angles (used only by renderer)
 		for (i = 0; i < po->segCount; ++i)
+		{
 			po->segs[i]->angle += delta;
+			P_UpdateSegLightOffset(po->segs[i]);
+		}
 
 		// update polyobject's angle
 		po->angle += delta;
diff --git a/src/p_setup.c b/src/p_setup.c
index f56b2f4ea..259d8f5ff 100644
--- a/src/p_setup.c
+++ b/src/p_setup.c
@@ -446,6 +446,26 @@ static inline float P_SegLengthFloat(seg_t *seg)
 }
 #endif
 
+/** Updates the light offset
+  *
+  * \param li Seg to update the light offsets of
+  */
+void P_UpdateSegLightOffset(seg_t *li)
+{
+	fixed_t extralight = 0;
+
+	extralight = -(8*FRACUNIT) +
+		FixedDiv(AngleFixed(R_PointToAngle2(0, 0,
+		abs(li->v1->x - li->v2->x),
+		abs(li->v1->y - li->v2->y))), 90*FRACUNIT) * 16;
+
+	// Between -1 and 1 for software, -8 and 8 for hardware
+	li->lightOffset = FixedFloor((extralight / 8) + (FRACUNIT / 2)) / FRACUNIT;
+#ifdef HWRENDER
+	li->hwLightOffset = FixedFloor(extralight + (FRACUNIT / 2)) / FRACUNIT;
+#endif
+}
+
 /** Loads the SEGS resource from a level.
   *
   * \param lump Lump number of the SEGS resource.
@@ -494,16 +514,7 @@ static void P_LoadRawSegs(UINT8 *data, size_t i)
 		li->numlights = 0;
 		li->rlights = NULL;
 
-		extralight = -(8*FRACUNIT) +
-			FixedDiv(AngleFixed(R_PointToAngle2(0, 0,
-			abs(li->v1->x - li->v2->x),
-			abs(li->v1->y - li->v2->y))), 90*FRACUNIT) * 16;
-
-		// Between -1 and 1 for software, -8 and 8 for hardware
-		li->lightOffset = FixedFloor((extralight / 8) + (FRACUNIT / 2)) / FRACUNIT;
-#ifdef HWRENDER
-		li->hwLightOffset = FixedFloor(extralight + (FRACUNIT / 2)) / FRACUNIT;
-#endif
+		P_UpdateSegLightOffset(li);
 	}
 }
 
diff --git a/src/p_setup.h b/src/p_setup.h
index 9abcfe5f6..c0b30ca6a 100644
--- a/src/p_setup.h
+++ b/src/p_setup.h
@@ -66,6 +66,7 @@ boolean P_DelWadFile(void);
 #endif
 boolean P_RunSOC(const char *socfilename);
 void P_WriteThings(lumpnum_t lump);
+void P_UpdateSegLightOffset(seg_t *li);
 size_t P_PrecacheLevelFlats(void);
 void P_AllocMapHeader(INT16 i);