From 5564db4f5af6a0db1ad5eabc7f39e9a39d7c2fc2 Mon Sep 17 00:00:00 2001
From: Jan <Laupetin@users.noreply.github.com>
Date: Sun, 5 Jul 2026 23:17:34 +0200
Subject: [PATCH] fix: t6 font crash (#881)

* fix: make sure t6 always has at least one kerning pair

* chore: ignore nonesense kerning pairs when dumping
---
 src/ObjLoading/Font/FontLoader.cpp.template | 15 ++++++++++----
 src/ObjWriting/Font/FontDumper.cpp.template | 23 ++++++++++++++++++---
 2 files changed, 31 insertions(+), 7 deletions(-)

diff --git a/src/ObjLoading/Font/FontLoader.cpp.template b/src/ObjLoading/Font/FontLoader.cpp.template
index 979420d8..02543156 100644
--- a/src/ObjLoading/Font/FontLoader.cpp.template
+++ b/src/ObjLoading/Font/FontLoader.cpp.template
@@ -306,14 +306,21 @@ namespace
                 }
                 
                 SortKerningPairs(font);
+                
+                if (!EnsureFontContainsGlyphsOfKerningPairs(font))
+                    return false;
             }
             else
             {
-                font.kerningPairs = nullptr;
+                // The game is bugged here and accesses the kerning pairs even when kerningPairsCount is set to 0.
+                // It always checks the first entry so we add a nonsense entry here that never matches
+                // to ensure that no kerning is applied on randomly matching bytes.
+                font.kerningPairsCount = 1;
+                font.kerningPairs = m_memory.Alloc<KerningPairs>(1);
+                font.kerningPairs[0].wFirst = 0;
+                font.kerningPairs[0].wSecond = 0;
+                font.kerningPairs[0].iKernAmount = 0;
             }
-            
-            if (!EnsureFontContainsGlyphsOfKerningPairs(font))
-                return false;
 #endif
 
             return true;
diff --git a/src/ObjWriting/Font/FontDumper.cpp.template b/src/ObjWriting/Font/FontDumper.cpp.template
index be9572db..4dc6720f 100644
--- a/src/ObjWriting/Font/FontDumper.cpp.template
+++ b/src/ObjWriting/Font/FontDumper.cpp.template
@@ -61,6 +61,20 @@ namespace
     }
 
 #ifdef FEATURE_T6
+    bool HasActualKerningPairs(const Font_s& font)
+    {
+        if (font.kerningPairs == nullptr)
+            return false;
+        if (font.kerningPairsCount > 1)
+            return true;
+        if (font.kerningPairsCount == 0)
+            return false;
+        
+        const auto& firstKerningPair = font.kerningPairs[0];
+        
+        return firstKerningPair.wFirst != 0 || firstKerningPair.wSecond != 0 || firstKerningPair.iKernAmount != 0;
+    }
+
     void CreateJsonKerningPair(JsonKerningPair& jKerningPair, const KerningPairs& kerningPair)
     {
         jKerningPair.firstLetter = kerningPair.wFirst;
@@ -91,9 +105,12 @@ namespace
             CreateJsonGlyph(jFont.glyphs[i], font.glyphs[i]);
 
 #ifdef FEATURE_T6
-        jFont.kerningPairs.resize(font.kerningPairsCount);
-        for (auto i = 0; i < font.kerningPairsCount; i++)
-            CreateJsonKerningPair(jFont.kerningPairs[i], font.kerningPairs[i]);
+        if (HasActualKerningPairs(font))
+        {
+            jFont.kerningPairs.resize(font.kerningPairsCount);
+            for (auto i = 0; i < font.kerningPairsCount; i++)
+                CreateJsonKerningPair(jFont.kerningPairs[i], font.kerningPairs[i]);
+        }
 #endif
     }