From 403e7d0eb4378c6c21012774ae5b41f22f265b6f Mon Sep 17 00:00:00 2001
From: Nico de Poel <ndepoel@gmail.com>
Date: Sun, 25 Apr 2021 19:45:53 +0200
Subject: [PATCH] Added struct definitions and marshaling code to obtain
 texture numbers for brush model surfaces

---
 Assets/Scripts/Data/QModel.cs        | 16 ++++++++++++++++
 Assets/Scripts/Data/QTexture.cs      | 23 +++++++++++++++++++++++
 Assets/Scripts/Modules/BrushModel.cs |  2 ++
 3 files changed, 41 insertions(+)

diff --git a/Assets/Scripts/Data/QModel.cs b/Assets/Scripts/Data/QModel.cs
index 37ec567..dd02aea 100644
--- a/Assets/Scripts/Data/QModel.cs
+++ b/Assets/Scripts/Data/QModel.cs
@@ -258,6 +258,8 @@ public struct QSurface
     [MarshalAs(UnmanagedType.ByValArray, SizeConst = QConstants.MaxLightmaps)] public int[] cachedLight;
     public bool cachedDLight;
     public IntPtr samples;  // Pointer to byte
+    
+    public QTexInfo TextureInfo => Marshal.PtrToStructure<QTexInfo>(texInfo);
 
     public IEnumerable<QGLPolyVert[]> GetPolygons()
     {
@@ -297,3 +299,17 @@ public struct QGLPolyVert
     public QVec2 textureUV;
     public QVec2 lightmapUV;
 }
+
+/// <summary>
+/// Managed equivalent of mtexinfo_t
+/// </summary>
+[StructLayout(LayoutKind.Sequential, Pack = 0)]
+public struct QTexInfo
+{
+    [MarshalAs(UnmanagedType.ByValArray, SizeConst = 2 * 4)] public float[] vecs;
+    public float mipAdjust;
+    public IntPtr texture;  // Pointer to texture_t
+    public int flags;
+
+    public QTexture Texture => Marshal.PtrToStructure<QTexture>(texture);
+}
diff --git a/Assets/Scripts/Data/QTexture.cs b/Assets/Scripts/Data/QTexture.cs
index 9e85928..104eca0 100644
--- a/Assets/Scripts/Data/QTexture.cs
+++ b/Assets/Scripts/Data/QTexture.cs
@@ -1,6 +1,25 @@
 using System;
 using System.Runtime.InteropServices;
 
+/// <summary>
+/// Managed equivalent of texture_t
+/// </summary>
+[StructLayout(LayoutKind.Sequential, Pack = 0, CharSet = CharSet.Ansi)]
+public struct QTexture
+{
+    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 16)] public string name;
+    public uint width, height;
+    public IntPtr glTexture;    // Pointer to gltexture_t
+    public IntPtr fullBright;   // Pointer to gltexture_t
+    public IntPtr warpImage;    // Pointer to gltexture_t
+
+    public uint TextureNum => QGLTexture.TexNumFromPtr(glTexture);
+    public uint FullBrightNum => QGLTexture.TexNumFromPtr(fullBright);
+    public uint WarpImageNum => QGLTexture.TexNumFromPtr(warpImage);
+    
+    // Rest of the fields are left out, so we don't unnecessarily marshal any unused data
+}
+
 /// <summary>
 /// Managed equivalent of gltexture_t
 /// </summary>
@@ -23,6 +42,10 @@ public class QGLTexture
     public char shirt;
     public char pants;
     public int visFrame;
+    
+    // Conveniently make use of the fact that texNum is the first field in QGLTexture,
+    // so we don't have to marshal the entire struct to get the texture number out of it.
+    public static uint TexNumFromPtr(IntPtr ptr) => ptr == IntPtr.Zero ? 0 : unchecked((uint)Marshal.ReadInt32(ptr));
 }
 
 /// <summary>
diff --git a/Assets/Scripts/Modules/BrushModel.cs b/Assets/Scripts/Modules/BrushModel.cs
index 8f5dda7..f3f8940 100644
--- a/Assets/Scripts/Modules/BrushModel.cs
+++ b/Assets/Scripts/Modules/BrushModel.cs
@@ -52,6 +52,8 @@ public class BrushModel
                 mesh.UploadMeshData(true);
                 meshes.Add(mesh);
             }
+
+            var texNum = surfaces[surfIdx].TextureInfo.Texture.TextureNum;
         }
         
         // DEBUG