Setup Material Texture

Path 1: SDF Material                Path 2: Assimp Material
  ├─ <material>                       ├─ Assimp.Material properties
  │  ├─ <diffuse>                     │  ├─ ColorDiffuse
  │  ├─ <emissive>                    │  ├─ ColorEmissive
  │  ├─ <specular>                    │  ├─ TextureDiffuse
  │  └─ <normal_map>                  │  └─ TextureNormal
  │                                   │
  └─ SDF2Unity.Material.*()           └─ sceneMaterials.ToUnity()
                    │                              │
                    ▼                              ▼
              CreateMaterial()  ← base material creation
                    │
                    ▼
              Set*() extension methods
              ├─ SetBaseColor()
              ├─ SetEmission()
              ├─ SetSpecular()
              ├─ SetNormalMap()
              ├─ SetTransparent() / SetOpaque()
              └─ ConvertToSpeedTree()

public static Material CreateMaterial(in string materialName = "")
// Creates a URP "Custom/URP/Simple Lit" material with defaults:
//   Render Queue: Geometry
//   Cull Mode:    Back (front-face rendering)
//   ZWrite:       Enabled
//   BaseColor:    White
//   Smoothness:   0 (fully rough)
//   EnvironmentReflections: 0.5
//   GPU Instancing: ON (_INSTANCING_ON + _DOTS_INSTANCING_ON)
//   Receive Shadows: ON

public static void SetBaseColor(this Material target, Color color)
// Sets _BaseColor property
// Auto-switches transparency:
//   color.a < 1.0 → SetTransparent()
//   color.a == 1.0 → SetOpaque()

// Transparent mode
public static void SetTransparent(this Material target)
// RenderType tag: "Transparent"
// _Surface: 1
// _SrcBlend: SrcAlpha
// _DstBlend: OneMinusSrcAlpha
// Render Queue: Transparent

// Opaque mode
public static void SetOpaque(this Material target)
// RenderType tag: "Opaque"
// _Surface: 0
// Render Queue: Geometry

public static void SetEmission(this Material target, Color color)
// _EmissionColor: color
// GlobalIllumination: None
// Enables _EMISSION shader keyword

public static void SetSpecular(this Material target, Color color)
// _SpecColor: color.rgb
// _Smoothness: color.a (smoothness packed in alpha)
// _SmoothnessSource: 0 (from specular alpha)
// Enables _SPECGLOSSMAP shader keyword

public static void SetNormalMap(this Material target, in string normalMapPath)
// Loads texture via MeshLoader.GetTexture()
// Sets _BumpMap texture
// Enables _NORMALMAP shader keyword

public static void ConvertToSpeedTree(this Material target)
// Swaps shader: "Custom/URP/Simple Lit" → "Universal Render Pipeline/Nature/SpeedTree8"
// Remaps: _BaseMap → _MainTex (with scale/offset)
// Sets _TwoSided: 0
// Disables EFFECT_BILLBOARD keyword

// Color properties
HasColorDiffuse    → SetBaseColor(diffuseColor)
                     // Note: alpha forced to 1.0 (Blender FBX override)
HasOpacity         → alpha = opacity; SetTransparent() if < 1.0
HasColorEmissive   → SetEmission(emissiveColor)
HasColorSpecular   → SetColor("_SpecColor", specularColor)
HasShininess       → Smoothness = 1.0 - Clamp01(Shininess)
HasReflectivity    → Smoothness = 1.0 - Clamp01(Reflectivity)

// Texture properties
HasTextureDiffuse  → _BaseMap texture
HasTextureNormal   → _BumpMap + _NORMALMAP keyword
HasBumpScaling     → _BumpScale (normal map strength)
HasTextureSpecular → _SpecGlossMap + _SPECGLOSSMAP keyword
HasTextureEmissive → _EmissionMap + _EMISSION keyword
HasTextureOpacity  → logged only (not applied)

// 1. Check embedded textures first (FBX "*{index}" convention)
// 2. Normalize path:
//    - Strip "model://" prefix
//    - Convert \\ to /
//    - Strip "//" Blender FBX prefix
// 3. Search directories (relative to mesh file):
""                  // Same directory
"../"               // Parent
"../../"            // Grandparent
"textures/"         // textures/ subfolder
"../textures/"      // Sibling textures/
"../materials/"     // Sibling materials/
"materials/"        // materials/ subfolder
// 4. Fallback: filename-only (strip all subdirectories)

// TGA files — custom loader
TextureUtil.LoadTGA(fileStream)
// Returns Texture2D from TGA binary data

// All other formats (PNG, JPG, BMP, etc.)
texture.LoadImage(File.ReadAllBytes(path))
// Unity's built-in image decoder with mipmap support

// Applied to all loaded textures:
texture.filterMode = FilterMode.Trilinear;
texture.anisoLevel = 4;

// Compress if dimensions are multiples of 4
if (width % 4 == 0 && height % 4 == 0)
	texture.Compress(true);

// Free CPU-side copy, keep GPU memory
texture.Apply(false, true);

// Prevent premature unloading
texture.hideFlags = HideFlags.DontUnloadUnusedAsset;