feat: *Generate Lightmap UVs* option in the glTF import inspector let…

…s you create a secondary texture coordinate set (similar to the Model Import Settings from other formats; closes #238)

ChangeLog.md

@@ -4,6 +4,10 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unrelease] - 
+### Added
+- *Generate Lightmap UVs* option in the glTF import inspector lets you create a secondary texture coordinate set (similar to the Model Import Settings from other formats; #238)
+
 ## [4.3.4] - 2021-10-26
 ### Added
 - Option to turn off Editor import by adding `GLTFAST_EDITOR_IMPORT_OFF` to the project's *Scripting Define Symbols* in the *Player Settings* (#256)  

Editor/Scripts/EditorImportSettings.cs

@@ -0,0 +1,33 @@
+// Copyright 2020-2021 Andreas Atteneder
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+using System;
+using UnityEngine.Serialization;
+
+namespace GLTFast.Editor {
+
+    /// <summary>
+    /// Editor Import specific settings (not relevant at runtime)
+    /// </summary>
+    [Serializable]
+    public class EditorImportSettings {
+
+        /// <summary>
+        /// Creates a secondary UV set on all meshes, if there is none present already.
+        /// Often used for lightmaps. 
+        /// </summary>
+        public bool generateSecondaryUVSet;
+    }
+}

Editor/Scripts/GltfImporter.cs

@@ -17,20 +17,25 @@
 
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using UnityEditor;
 #if UNITY_2020_2_OR_NEWER
 using UnityEditor.AssetImporters;
 #else
 using UnityEditor.Experimental.AssetImporters;
 #endif
 using UnityEngine;
+using UnityEngine.Rendering;
 using Object = UnityEngine.Object;
 
 namespace GLTFast.Editor {
 
     [ScriptedImporter(1,new [] {"gltf","glb"})] 
     public class GltfImporter : ScriptedImporter {
 
+        [SerializeField]
+        EditorImportSettings editorImportSettings;
+
         [SerializeField]
         ImportSettings importSettings;
 
@@ -68,8 +73,13 @@ public override void OnImportAsset(AssetImportContext ctx) {
                 logger
                 );
 
-            if (importSettings == null) {
+            if (editorImportSettings == null) {
                 // Design-time import specific settings
+                editorImportSettings = new EditorImportSettings();
+            }
+
+            if (importSettings == null) {
+                // Design-time import specific changes to default settings
                 importSettings = new ImportSettings {
                     // Avoid naming conflicts by default
                     nodeNameMethod = ImportSettings.NameImportMethod.OriginalUnique
@@ -123,6 +133,9 @@ public override void OnImportAsset(AssetImportContext ctx) {
                 var meshes = m_Gltf.GetMeshes();
                 if (meshes != null) {
                     foreach (var mesh in meshes) {
+                        if (editorImportSettings.generateSecondaryUVSet && !HasSecondaryUVs(mesh)) {
+                            Unwrapping.GenerateSecondaryUVSet(mesh);
+                        }
                         AddObjectToAsset(ctx, $"meshes/{mesh.name}", mesh);
                     }
                 }
@@ -209,6 +222,11 @@ string GetUniqueAssetName(string originalName) {
             }
             return originalName;
         }
+
+        static bool HasSecondaryUVs(Mesh mesh) {
+            var attributes = mesh.GetVertexAttributes();
+            return attributes.Any(attribute => attribute.attribute == VertexAttribute.TexCoord1);
+        }
     }
 }