From ec3d81a34ff99d0226a239073bbb13a0013c53fb Mon Sep 17 00:00:00 2001
From: Shiny Metagross <30511800+ShinyMetagross@users.noreply.github.com>
Date: Fri, 1 Jul 2022 11:49:13 -0700
Subject: [PATCH] More fixes

- Let's fill the holes of serialized data so it can properly be removed instead of leaving undefined behavior behind.
- Added CMDL_HIDEMODEL flag. This makes a model index invisible.
---
 src/playsim/p_actionfunctions.cpp  | 27 +++++++++++++--------------
 src/r_data/models.cpp              |  4 ++--
 wadsrc/static/zscript/constants.zs |  3 ++-
 3 files changed, 17 insertions(+), 17 deletions(-)

diff --git a/src/playsim/p_actionfunctions.cpp b/src/playsim/p_actionfunctions.cpp
index 7668aae4b..3d36f03c5 100644
--- a/src/playsim/p_actionfunctions.cpp
+++ b/src/playsim/p_actionfunctions.cpp
@@ -5030,7 +5030,8 @@ DEFINE_ACTION_FUNCTION(AActor, A_SetMugshotState)
 
 enum ChangeModelFlags
 {
-	CMDL_WEAPONTOPLAYER = 1
+	CMDL_WEAPONTOPLAYER = 1,
+	CMDL_HIDEMODEL = 1 << 1,
 };
 
 DEFINE_ACTION_FUNCTION(AActor, A_ChangeModel)
@@ -5067,17 +5068,21 @@ DEFINE_ACTION_FUNCTION(AActor, A_ChangeModel)
 	int maxModels = mobj->modelData->modelIDs.Size();
 	int maxSkins = mobj->modelData->skinIDs.Size();
 
-	int queryModel = model != NAME_None ? FindModel(modelpath.GetChars(), model.GetChars()) : -1;
+	int queryModel = !(flags & CMDL_HIDEMODEL) ? model != NAME_None ? FindModel(modelpath.GetChars(), model.GetChars()) : -1 : -2;
 
 	mobj->modelData->modelDef = modeldef;
 	if(maxModels > index) mobj->modelData->modelIDs.Pop(mobj->modelData->modelIDs[index]);
 	if(maxSkins > index)  mobj->modelData->skinIDs.Pop(mobj->modelData->skinIDs[index]);
 
+	//[SM] - We need to fill up any holes this new index will make so that it doesn't leave behind any undefined behavior
+	while ((int)mobj->modelData->modelIDs.Size() < index) mobj->modelData->modelIDs.Push(-1);
+	while ((int)mobj->modelData->skinIDs.Size() < index) mobj->modelData->skinIDs.Push(FNullTextureID());
+
 	mobj->modelData->modelIDs.Insert(index, queryModel);
 	mobj->modelData->skinIDs.Insert(index, skin != NAME_None ? LoadSkin(skinpath.GetChars(), skin.GetChars()) : FNullTextureID());
 
 	//[SM] - We need to serialize file paths and model names so that they are pushed on loading save files. Likewise, let's not include models that were already parsed when initialized.
-	if (model != NAME_None)
+	if (queryModel >= 0)
 	{
 		FString fullName;
 		fullName.Format("%s%s", modelpath.GetChars(), model.GetChars());
@@ -5089,20 +5094,14 @@ DEFINE_ACTION_FUNCTION(AActor, A_ChangeModel)
 	}
 
 	//[SM] - if an indice of modelIDs or skinIDs comes up blank and it's the last one, just delete it. For using very large amounts of indices, common sense says to just not run this repeatedly.
-	for (int i = 0; i < maxModels; i++)
-	{
-		if (mobj->modelData->modelIDs.Last() == -1) mobj->modelData->modelIDs.Pop(mobj->modelData->modelIDs.Last());
-		else break;
-	}
-	for (int i = 0; i < maxSkins; i++)
-	{
-		if (mobj->modelData->skinIDs.Last() == FNullTextureID()) mobj->modelData->skinIDs.Pop(mobj->modelData->skinIDs.Last());
-		else break;
-	}
+	while (mobj->modelData->modelIDs.Size() > 0 && mobj->modelData->modelIDs.Last() == -1)
+		mobj->modelData->modelIDs.Pop(mobj->modelData->modelIDs.Last());
+	while (mobj->modelData->skinIDs.Size() > 0 && mobj->modelData->skinIDs.Last() == FNullTextureID())
+		mobj->modelData->skinIDs.Pop(mobj->modelData->skinIDs.Last());
+	
 	if (mobj->modelData->modelIDs.Size() == 0 && mobj->modelData->skinIDs.Size() == 0 && modeldef == NAME_None)
 	{
 		mobj->hasmodel = mobj->modelData->hasModel;
-		mobj->modelData;
 		mobj->modelData->modelIDs.Reset();
 		mobj->modelData->skinIDs.Reset();
 		mobj->modelData->Destroy();
diff --git a/src/r_data/models.cpp b/src/r_data/models.cpp
index 7e9e8435a..825a7d0cf 100644
--- a/src/r_data/models.cpp
+++ b/src/r_data/models.cpp
@@ -285,7 +285,7 @@ void RenderFrameModels(FModelRenderer *renderer, FLevelLocals *Level, const FSpr
 		{
 			if (i < (int)actor->modelData->modelIDs.Size())
 			{
-				if(actor->modelData->modelIDs[i] >= 0)
+				if(actor->modelData->modelIDs[i] != -1)
 					tempModelIDs[i] = actor->modelData->modelIDs[i];
 			}
 			if (i < (int)actor->modelData->skinIDs.Size())
@@ -294,7 +294,7 @@ void RenderFrameModels(FModelRenderer *renderer, FLevelLocals *Level, const FSpr
 					tempSkinIDs[i] = actor->modelData->skinIDs[i];
 			}
 		}
-		if (tempModelIDs[i] != -1)
+		if (tempModelIDs[i] >= 0)
 		{
 			FModel * mdl = Models[tempModelIDs[i]];
 			auto tex = tempSkinIDs[i].isValid() ? TexMan.GetGameTexture(tempSkinIDs[i], true) : nullptr;
diff --git a/wadsrc/static/zscript/constants.zs b/wadsrc/static/zscript/constants.zs
index ebc317b77..15a1514bf 100644
--- a/wadsrc/static/zscript/constants.zs
+++ b/wadsrc/static/zscript/constants.zs
@@ -368,7 +368,8 @@ enum ERadiusGiveFlags
 // Change model flags
 enum ChangeModelFlags
 {
-	CMDL_WEAPONTOPLAYER = 1
+	CMDL_WEAPONTOPLAYER = 1,
+	CMDL_HIDEMODEL = 1 << 1,
 };
 
 // Activation flags