From 0bfc51f55e030d355225265f80e60c0a0bba2733 Mon Sep 17 00:00:00 2001
From: Daniel Gibson <metalcaedes@gmail.com>
Date: Sun, 6 Nov 2022 18:12:54 +0100
Subject: [PATCH] Fix renderlights loaded from savegames aliasing other lights

Some entities wrote the handle from gameRenderWorld->AddLightDef()
into savegames and reused it after restoring it.
That's a bad idea, because at that point the handle most likely belongs
to something else (likely some idLight). The most visible issue this
can create is that the flashlight may not work correctly after loading
a savegame with flashlight on, when it happens to alias a light that's
updated each frame to (mostly) being off..

The correct way to handle this (THAT FOR SOME REASON WAS ALREADY
IMPLEMENTED IN D3XP BUT NOT THE BASE GAME - WHY?!) is to get a fresh
handle with AddLightDef() when restoring a savegame - unless the handle
was -1, which means that the light didn't exist when saving.

fixes #495
---
 game/Moveable.cpp   |  9 +++++++++
 game/Projectile.cpp |  5 +++++
 game/Weapon.cpp     | 14 +++++++++++++-
 3 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/game/Moveable.cpp b/game/Moveable.cpp
index e13ecd6..e3458b3 100644
--- a/game/Moveable.cpp
+++ b/game/Moveable.cpp
@@ -810,6 +810,15 @@ void idExplodingBarrel::Restore( idRestoreGame *savefile ) {
 	savefile->ReadInt( particleTime );
 	savefile->ReadInt( lightTime );
 	savefile->ReadFloat( time );
+
+	// DG: enforce getting fresh handle, else this may be tied to an unrelated light!
+	if ( lightDefHandle != -1 ) {
+		lightDefHandle = gameRenderWorld->AddLightDef( &light );
+	}
+	// DG: same for render entity
+	if ( particleModelDefHandle != -1 ) {
+		particleModelDefHandle = gameRenderWorld->AddEntityDef( &particleRenderEntity );
+	}
 }
 
 /*
diff --git a/game/Projectile.cpp b/game/Projectile.cpp
index c353ca0..6460ae0 100644
--- a/game/Projectile.cpp
+++ b/game/Projectile.cpp
@@ -157,6 +157,11 @@ void idProjectile::Restore( idRestoreGame *savefile ) {
 
 	savefile->ReadRenderLight( renderLight );
 	savefile->ReadInt( (int &)lightDefHandle );
+	// DG: enforce getting fresh handle, else this may be tied to an unrelated light!
+	if ( lightDefHandle != -1 ) {
+		lightDefHandle = gameRenderWorld->AddLightDef( &renderLight );
+	}
+
 	savefile->ReadVec3( lightOffset );
 	savefile->ReadInt( lightStartTime );
 	savefile->ReadInt( lightEndTime );
diff --git a/game/Weapon.cpp b/game/Weapon.cpp
index a381ae2..727e061 100644
--- a/game/Weapon.cpp
+++ b/game/Weapon.cpp
@@ -453,12 +453,21 @@ void idWeapon::Restore( idRestoreGame *savefile ) {
 
 	savefile->ReadInt( guiLightHandle );
 	savefile->ReadRenderLight( guiLight );
-
+	// DG: we need to get a fresh handle, otherwise this will be tied to a completely unrelated light!
+	if ( guiLightHandle != -1 ) {
+		guiLightHandle = gameRenderWorld->AddLightDef( &guiLight );
+	}
 	savefile->ReadInt( muzzleFlashHandle );
 	savefile->ReadRenderLight( muzzleFlash );
+	if ( muzzleFlashHandle != -1 ) { // DG: enforce getting fresh handle
+		muzzleFlashHandle = gameRenderWorld->AddLightDef( &muzzleFlash );
+	}
 
 	savefile->ReadInt( worldMuzzleFlashHandle );
 	savefile->ReadRenderLight( worldMuzzleFlash );
+	if ( worldMuzzleFlashHandle != -1 ) { // DG: enforce getting fresh handle
+		worldMuzzleFlashHandle = gameRenderWorld->AddLightDef( &worldMuzzleFlash );
+	}
 
 	savefile->ReadVec3( flashColor );
 	savefile->ReadInt( muzzleFlashEnd );
@@ -516,6 +525,9 @@ void idWeapon::Restore( idRestoreGame *savefile ) {
 
 	savefile->ReadInt( nozzleGlowHandle );
 	savefile->ReadRenderLight( nozzleGlow );
+	if ( nozzleGlowHandle != -1 ) { // DG: enforce getting fresh handle
+		nozzleGlowHandle = gameRenderWorld->AddLightDef( &nozzleGlow );
+	}
 
 	savefile->ReadVec3( nozzleGlowColor );
 	savefile->ReadMaterial( nozzleGlowShader );