From 8a791816ed3215b0b919fe07ece7e376a2b053c0 Mon Sep 17 00:00:00 2001
From: Jan Laupetin <jan@laupetin.net>
Date: Mon, 4 May 2026 18:31:12 +0200
Subject: [PATCH] chore: set XSurface deformed property when applicable

---
 src/Common/Game/IW5/IW5_Assets.h                |  5 +++++
 src/ObjLoading/XModel/LoaderXModel.cpp.template | 13 ++++++++++---
 src/ObjWriting/XModel/XModelDumper.cpp.template | 12 ++++++++++++
 3 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/src/Common/Game/IW5/IW5_Assets.h b/src/Common/Game/IW5/IW5_Assets.h
index ae694a85..e61fb58b 100644
--- a/src/Common/Game/IW5/IW5_Assets.h
+++ b/src/Common/Game/IW5/IW5_Assets.h
@@ -516,6 +516,11 @@ namespace IW5
 
     typedef tdef_align32(16) XSurfaceTri XSurfaceTri16;
 
+    enum XSurfaceFlag
+    {
+        XSURFACE_FLAG_DEFORMED = 0x40
+    };
+
     struct XSurface
     {
         unsigned char tileMode;
diff --git a/src/ObjLoading/XModel/LoaderXModel.cpp.template b/src/ObjLoading/XModel/LoaderXModel.cpp.template
index 018ada36..b3332821 100644
--- a/src/ObjLoading/XModel/LoaderXModel.cpp.template
+++ b/src/ObjLoading/XModel/LoaderXModel.cpp.template
@@ -752,9 +752,16 @@ namespace
 
             // Since bone weights are sorted by weight count, the last must have the highest weight count
             const auto maxWeightCount = common.m_vertex_bone_weights[xmodelToCommonVertexIndexLookup[xmodelToCommonVertexIndexLookup.size() - 1]].weightCount;
-            const auto modelIsRigid = maxWeightCount <= 1;
+            const auto surfaceIsRigid = maxWeightCount <= 1;
 
-            if (modelIsRigid)
+#if defined(FEATURE_IW3) || defined(FEATURE_IW4)
+            surface.deformed = !surfaceIsRigid;
+#else
+            if (!surfaceIsRigid)
+                surface.flags |= XSURFACE_FLAG_DEFORMED;
+#endif
+
+            if (surfaceIsRigid)
             {
                 constexpr auto maxVerticesForRigid = static_cast<size_t>(std::numeric_limits<decltype(XSurface::vertCount)>::max());
                 if (vertexOffset + xmodelToCommonVertexIndexLookup.size() > maxVerticesForRigid)
@@ -790,7 +797,7 @@ namespace
 
             if (!common.m_bone_weight_data.weights.empty())
             {
-                if (modelIsRigid)
+                if (surfaceIsRigid)
                 {
                     CreateVertListData(surface, xmodelToCommonVertexIndexLookup, common);
                 }
diff --git a/src/ObjWriting/XModel/XModelDumper.cpp.template b/src/ObjWriting/XModel/XModelDumper.cpp.template
index 434750af..06a7ff08 100644
--- a/src/ObjWriting/XModel/XModelDumper.cpp.template
+++ b/src/ObjWriting/XModel/XModelDumper.cpp.template
@@ -423,6 +423,12 @@ namespace
 
             if (surface.vertList)
             {
+#if defined(FEATURE_IW3) || defined(FEATURE_IW4)
+                assert(!surface.deformed);
+#else
+                assert((surface.flags & XSURFACE_FLAG_DEFORMED) == 0);
+#endif
+                
                 for (auto vertListIndex = 0u; vertListIndex < surface.vertListCount; vertListIndex++)
                 {
                     const auto& vertList = surface.vertList[vertListIndex];
@@ -442,6 +448,12 @@ namespace
             auto vertsBlendOffset = 0u;
             if (surface.vertInfo.vertsBlend)
             {
+#if defined(FEATURE_IW3) || defined(FEATURE_IW4)
+                assert(surface.deformed);
+#else
+                assert((surface.flags & XSURFACE_FLAG_DEFORMED) > 0);
+#endif
+                
                 // 1 bone weight
                 for (auto vertIndex = 0; vertIndex < surface.vertInfo.vertCount[0]; vertIndex++)
                 {