Recursively traverse the BSP tree and create surface meshes per node

Assets/Scripts/Data/QModel.cs

@@ -238,7 +238,7 @@ public struct QSubModel
 
     public QNode GetHeadNode(QModel model)
     {
-        IntPtr nodePtr = IntPtr.Add(model.nodes, headNode[0]);
+        IntPtr nodePtr = IntPtr.Add(model.nodes, headNode[0] * Marshal.SizeOf<QNode>());
         return Marshal.PtrToStructure<QNode>(nodePtr);
     }
 }
@@ -249,12 +249,16 @@ public struct QSubModel
 [StructLayout(LayoutKind.Sequential, Pack = 0)]
 public struct QNode
 {
+    // Common with leaf
     public int contents;    // 0 for nodes, negative for leafs
     public int visFrame;
     public QVec3 mins, maxs;
     public IntPtr parent;   // Pointer to mnode_t
+    
+    // Node specific
     public IntPtr plane;    // Pointer to mplane_t
     [MarshalAs(UnmanagedType.ByValArray, SizeConst = 2)] public IntPtr[] children;   // Array of pointers to mnode_t
+    
     public uint firstSurface;
     public uint numSurfaces;
 

Assets/Scripts/Modules/BrushModel.cs

@@ -7,6 +7,12 @@ public class BrushModel
     private readonly string name;
     private readonly List<Mesh> meshes = new List<Mesh>();
 
+    // Reusable temporary data containers
+    private readonly List<Vector3> tempVertices = new List<Vector3>();
+    private readonly List<Vector2> tempTextureUVs = new List<Vector2>();
+    private readonly List<Vector2> tempLightmapUVs = new List<Vector2>();
+    private readonly List<ushort> tempIndices = new List<ushort>();
+    
     public BrushModel(string name)
     {
         this.name = name;
@@ -17,48 +23,12 @@ public class BrushModel
         var subModels = model.SubModels;
         var surfaces = model.Surfaces;
 
-        List<Vector3> vertices = new List<Vector3>();
-        List<Vector2> textureUVs = new List<Vector2>();
-        List<Vector2> lightmapUVs = new List<Vector2>();
-        List<ushort> indices = new List<ushort>();
-        
-        for (int surfIdx = 0; surfIdx < surfaces.Length; ++surfIdx)
+        for (int modelIdx = 0; modelIdx < subModels.Length; ++modelIdx)
         {
-            foreach (var polyVerts in surfaces[surfIdx].GetPolygons())
-            {
-                vertices.Clear();
-                textureUVs.Clear();
-                lightmapUVs.Clear();
-                indices.Clear();
-
-                for (int vertIdx = 0; vertIdx < polyVerts.Length; ++vertIdx)
-                {
-                    vertices.Add(polyVerts[vertIdx].position.ToVector3().ToUnity());
-                    textureUVs.Add(polyVerts[vertIdx].textureUV.ToVector2());
-                    lightmapUVs.Add(polyVerts[vertIdx].lightmapUV.ToVector2());
-                }
-
-                // Reconstruct triangle fan
-                for (ushort index = 2; index < polyVerts.Length; ++index)
-                {
-                    indices.Add(0);
-                    indices.Add((ushort)(index - 1));
-                    indices.Add(index);
-                }
-                
-                Mesh mesh = new Mesh();
-                mesh.SetVertices(vertices);
-                mesh.SetUVs(0, textureUVs);
-                mesh.SetUVs(1, lightmapUVs);
-                mesh.SetIndices(indices, MeshTopology.Triangles, 0);
-                mesh.RecalculateNormals();
-                mesh.UploadMeshData(true);
-                meshes.Add(mesh);
-            }
-
-            var texNum = surfaces[surfIdx].TextureInfo.Texture.TextureNum;
+            var headNode = subModels[modelIdx].GetHeadNode(model);
+            CreateNodeMeshes(headNode, surfaces);
         }
-        
+
         // DEBUG
         var go = new GameObject(name);
         var mat = new Material(Shader.Find("Universal Render Pipeline/Simple Lit"));
@@ -83,4 +53,59 @@ public class BrushModel
         
         go.transform.SetPositionAndRotation(Vector3.zero, Quaternion.identity);
     }
+
+    private void CreateNodeMeshes(QNode node, QSurface[] surfaces)
+    {
+        if (node.contents < 0)  // Leaf node
+            return;
+        
+        CreateSurfaceMeshes(node, surfaces);
+
+        foreach (var childNode in node.Children)
+        {
+            CreateNodeMeshes(childNode, surfaces);
+        }
+    }
+
+    private void CreateSurfaceMeshes(QNode node, QSurface[] surfaces)
+    {
+        for (int surfIdx = 0; surfIdx < node.numSurfaces; ++surfIdx)
+        {
+            var surface = surfaces[node.firstSurface + surfIdx];
+                
+            foreach (var polyVerts in surface.GetPolygons())
+            {
+                tempVertices.Clear();
+                tempTextureUVs.Clear();
+                tempLightmapUVs.Clear();
+                tempIndices.Clear();
+
+                for (int vertIdx = 0; vertIdx < polyVerts.Length; ++vertIdx)
+                {
+                    tempVertices.Add(polyVerts[vertIdx].position.ToVector3().ToUnity());
+                    tempTextureUVs.Add(polyVerts[vertIdx].textureUV.ToVector2());
+                    tempLightmapUVs.Add(polyVerts[vertIdx].lightmapUV.ToVector2());
+                }
+
+                // Reconstruct triangle fan
+                for (ushort index = 2; index < polyVerts.Length; ++index)
+                {
+                    tempIndices.Add(0);
+                    tempIndices.Add((ushort) (index - 1));
+                    tempIndices.Add(index);
+                }
+
+                Mesh mesh = new Mesh();
+                mesh.SetVertices(tempVertices);
+                mesh.SetUVs(0, tempTextureUVs);
+                mesh.SetUVs(1, tempLightmapUVs);
+                mesh.SetIndices(tempIndices, MeshTopology.Triangles, 0);
+                mesh.RecalculateNormals();
+                mesh.UploadMeshData(true);
+                meshes.Add(mesh);
+            }
+
+            var texNum = surface.TextureInfo.Texture.TextureNum;
+        }
+    }
 }