From 1535f95cf11b92185ce2918b236ee8a25e81cd61 Mon Sep 17 00:00:00 2001
From: Wojtek Figat <wojtek@figat.pl>
Date: Tue, 3 Feb 2026 13:18:02 +0100
Subject: [PATCH] Fix mesh collision proxy setup for meshes using packed
 positions format

#3791
---
 Source/Engine/Core/Math/Half.h                | 13 ++++++++
 Source/Engine/Core/Math/Packed.cpp            | 10 ------
 Source/Engine/Core/Math/Packed.h              | 11 +++++--
 .../Engine/Graphics/Models/CollisionProxy.h   | 33 ++++++++++++++-----
 Source/Engine/Graphics/Models/MeshBase.cpp    |  5 +--
 5 files changed, 49 insertions(+), 23 deletions(-)

diff --git a/Source/Engine/Core/Math/Half.h b/Source/Engine/Core/Math/Half.h
index 2617649d0..ebb2cc951 100644
--- a/Source/Engine/Core/Math/Half.h
+++ b/Source/Engine/Core/Math/Half.h
@@ -248,6 +248,19 @@ public:
     explicit Half4(const Color& c);
     explicit Half4(const Rectangle& rect);
 
+    operator Float2() const
+    {
+        return ToFloat2();
+    }
+    operator Float3() const
+    {
+        return ToFloat3();
+    }
+    operator Float4() const
+    {
+        return ToFloat4();
+    }
+
 public:
     Float2 ToFloat2() const;
     Float3 ToFloat3() const;
diff --git a/Source/Engine/Core/Math/Packed.cpp b/Source/Engine/Core/Math/Packed.cpp
index 55ebd9ccf..b22e65d3e 100644
--- a/Source/Engine/Core/Math/Packed.cpp
+++ b/Source/Engine/Core/Math/Packed.cpp
@@ -41,16 +41,6 @@ FloatR10G10B10A2::FloatR10G10B10A2(const float* values)
 {
 }
 
-FloatR10G10B10A2::operator Float3() const
-{
-    return ToFloat3();
-}
-
-FloatR10G10B10A2::operator Float4() const
-{
-    return ToFloat4();
-}
-
 Float3 FloatR10G10B10A2::ToFloat3() const
 {
     Float3 vectorOut;
diff --git a/Source/Engine/Core/Math/Packed.h b/Source/Engine/Core/Math/Packed.h
index 8e3aad41f..c5b5e827f 100644
--- a/Source/Engine/Core/Math/Packed.h
+++ b/Source/Engine/Core/Math/Packed.h
@@ -40,9 +40,14 @@ struct FLAXENGINE_API FloatR10G10B10A2
     {
         return Value;
     }
-
-    operator Float3() const;
-    operator Float4() const;
+    operator Float3() const
+    {
+        return ToFloat3();
+    }
+    operator Float4() const
+    {
+        return ToFloat4();
+    }
 
     FloatR10G10B10A2& operator=(const FloatR10G10B10A2& other)
     {
diff --git a/Source/Engine/Graphics/Models/CollisionProxy.h b/Source/Engine/Graphics/Models/CollisionProxy.h
index 5dc021867..eba17cf4e 100644
--- a/Source/Engine/Graphics/Models/CollisionProxy.h
+++ b/Source/Engine/Graphics/Models/CollisionProxy.h
@@ -6,7 +6,9 @@
 #include "Engine/Core/Math/Transform.h"
 #include "Engine/Core/Math/Ray.h"
 #include "Engine/Core/Math/CollisionsHelper.h"
+#include "Engine/Core/Math/Packed.h"
 #include "Engine/Core/Collections/Array.h"
+#include "Engine/Graphics/PixelFormat.h"
 
 /// <summary>
 /// Helper container used for detailed triangle mesh intersections tests.
@@ -31,23 +33,38 @@ public:
     }
 
     template<typename IndexType>
-    void Init(uint32 vertices, uint32 triangles, const Float3* positions, const IndexType* indices, uint32 positionsStride = sizeof(Float3))
+    void Init(uint32 vertices, uint32 triangles, const Float3* positions, const IndexType* indices, uint32 positionsStride = sizeof(Float3), PixelFormat positionsFormat = PixelFormat::R32G32B32_Float)
     {
         Triangles.Clear();
         Triangles.EnsureCapacity(triangles, false);
         const IndexType* it = indices;
-        for (uint32 i = 0; i < triangles; i++)
+#define LOOP_BEGIN() \
+    for (uint32 i = 0; i < triangles; i++) \
+    { \
+        const IndexType i0 = *(it++); \
+        const IndexType i1 = *(it++); \
+        const IndexType i2 = *(it++); \
+        if (i0 < vertices && i1 < vertices && i2 < vertices) \
         {
-            const IndexType i0 = *(it++);
-            const IndexType i1 = *(it++);
-            const IndexType i2 = *(it++);
-            if (i0 < vertices && i1 < vertices && i2 < vertices)
-            {
+#define LOOP_END() } }
+        if (positionsFormat == PixelFormat::R32G32B32_Float)
+        {
+            LOOP_BEGIN()
 #define GET_POS(idx) *(const Float3*)((const byte*)positions + positionsStride * idx)
                 Triangles.Add({ GET_POS(i0), GET_POS(i1), GET_POS(i2) });
 #undef GET_POS
-            }
+            LOOP_END()
         }
+        else if (positionsFormat == PixelFormat::R16G16B16A16_Float)
+        {
+            LOOP_BEGIN()
+#define GET_POS(idx) (Float3)*(const Half4*)((const byte*)positions + positionsStride * idx)
+                Triangles.Add({ GET_POS(i0), GET_POS(i1), GET_POS(i2) });
+#undef GET_POS
+            LOOP_END()
+        }
+#undef LOOP_BEGIN
+#undef LOOP_END
     }
 
     void Clear()
diff --git a/Source/Engine/Graphics/Models/MeshBase.cpp b/Source/Engine/Graphics/Models/MeshBase.cpp
index 3434cd91a..91ed892ea 100644
--- a/Source/Engine/Graphics/Models/MeshBase.cpp
+++ b/Source/Engine/Graphics/Models/MeshBase.cpp
@@ -470,10 +470,11 @@ bool MeshBase::Init(uint32 vertices, uint32 triangles, const Array<const void*,
 
     // Init collision proxy
 #if MODEL_USE_PRECISE_MESH_INTERSECTS
+    VertexElement positionsElement = vbLayout[0]->FindElement(VertexElement::Types::Position);
     if (use16BitIndexBuffer)
-        _collisionProxy.Init<uint16>(vertices, triangles, (const Float3*)vbData[0], (const uint16*)ibData);
+        _collisionProxy.Init<uint16>(vertices, triangles, (const Float3*)vbData[0], (const uint16*)ibData, vertexBuffer0->GetStride(), positionsElement.Format);
     else
-        _collisionProxy.Init<uint32>(vertices, triangles, (const Float3*)vbData[0], (const uint32*)ibData);
+        _collisionProxy.Init<uint32>(vertices, triangles, (const Float3*)vbData[0], (const uint32*)ibData, vertexBuffer0->GetStride(), positionsElement.Format);
 #endif
 
     // Free old buffers