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Ürban PAD to Unity Workflow


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The new, easy way to create a city and export it to Unity

Published in: Spiritual, Technology
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Ürban PAD to Unity Workflow

  1. 1. Ürban PAD to Unity workflow1 Basic settingsIt is possible to export directly into FBX format from Ürban PAD, allowing a direct import into Unity.However, there is a limitation in Unity we will have to get around: the material assignment.1.1 Material assignmentAs stated in the Unity documentation, materials are imported only with diffuse textures.This leads to a long and painful post-process in order to identify the materials, assign them the correctshaders and assign the right textures in the shader slots.Moreover, Unitys default shader implementation is missing the DiffuseNormalSpecular that is one ofthe most commonly used in Ürban PAD.We decided to develop our own custom import script that would automatically assign the correctshaders and textures to the materials, and provide an implementation for the missing shaders.1.2 Setting a Unity projectBe careful, the following steps must be done only once for a given Unity project, priorimporting any data exported in Ürban PAD.Launch Unity, and then click File -> New project 1.You will be able to add many packages to your new project 1, but you dont need any of them rightnow. Do not worry; you will be able to import any of those packages later if needed. Hit Create 2 andyour new project will be created. 1
  2. 2. Open the Project window by clicking Window -> Project 1.Then right click in the project window and click on Show in explorer 1. . 2
  3. 3. It will open the project folder in a new explorer window. Open its Assets folder.The Gamr7 custom Unity resources (scripts and shaders) are located in the resources/Unity sub-folderof the Ürban PAD project folder. Copy the content of the resources/Unity folder in the Assets folderpreviously opened.The resulting folders hierarchy after this operation must look like this: Unity Project |__ Assets |__ Editor |__ G7_UnityImport.js |__ Shaders |__ G7_DiffuseNormalSpecular.shader |__ G7_Alpha-DiffuseNormalSpecular.shader2 Export from Ürban PADThe export button 1 is located in the top left corner of Ürban PAD. You can also hit Ctrl+e to open theexport window.2.1 Export a sector from Sector Editor  Select the Unity format 1.  Chose the folder where you want to export your data 2. By default, the export folder is the unity folder located at the root of your Ürban PAD project.  Select the usual export options you want to use 3.  Hit the validation button 4 and wait for the progress bar to disappear. 3
  4. 4. 2.2 Export a city from City Editor  Select the Unity format 1.  Chose the folder where you want to export your data 2. By default, the export folder is the unity folder located at the root of your Ürban PAD project’s folder.  Select the usual export options you want to use 3. o Bu using the Multi Files option, you will divide your city in many files: one per road segment, crossroad or sector. o You can pack your city on a grid; which allows you to choose the size of the city blocs you will obtain.  Hit the validation button 4 and wait for the progress bar to disappear.Now that you have exported your city, you should have a folder containing these files and folders: My exported city folder |__ models |__ textures |__ texture_1.png |__ texture_2.tga |__ … |__ multi_export_global_file.xml |__ couple_1.fbx |__ couple_1.xml |__ couple_2.fbx |__ couple_2.xml |__ … 4
  5. 5. The number of couple of .fbx and .xml files depends on the options you have chosen and the size ofyour city.3 Import into UnityThere is no import command in Unity. Simply drop your resources into the Assets directory of yourprojects root folder. Then when you set the focus back to the Unity window, it automatically detectsthat new assets were added and starts importing them.So, here is the procedure to follow to import your data in Unity :  Navigate to the place where you exported your Ürban PAD data.  Copy the .fbx file(s), the .xml file(s) and the textures folder, and paste them anywhere under the Assets folder. This can be directly in the Assets folder or in any sub-folder.  Return to Unity, and you should see an Importing Assets progress bar pop up. When its finished, your assets will be available in the Unity Project window 1.3.1 Material IssueHow our material process worksAlong with each .fbx file, we export a .xml file with the same base name. This file lists all the materialsused in the corresponding .fbx, identified with their IDs, and provides for each material:  The shader format (ex: "D" stands for Diffuse, "DNS" stands for DiffuseNormalSpecular)  The list of the textures referenced by the material with their semantic ("diffuse", "normal", "specular"...)Here is an example of our xml data: <material id="material_123" shader_format="DNS"> <texture semantic="specular">default_specular.jpg</texture> <texture semantic="diffuse">grey_pavement.jpg</texture> <texture semantic="normal">grey_pavement_normal.jpg</texture> </material>We have developed a script, named G7_UnityImport.js, that is automatically called during the importprocess.It parses the .xml materials file and assigns the correct shader and textures to the material beingimported. 5
  6. 6. We added some shaders implementations that were missing in Unity default resources, currently:  G7_DiffuseNormalSpecular.shader : DNS without transparency  G7_Alpha-DiffuseNormalSpecular.shader : DNS with transparencyImport models with materialsImport your assets as previously described. At the end of the process, a NormalMap settings windowmight pop up:This is because textures used as Normal Maps must be explicitly declared as such in Unity. Click Fixnow 1 to resolve this issue.Add a single model to a SceneTo add the model to a Scene, first activate the Scene by double-clicking it in the Project window, thendrag and drop the fbx model node from the Project window to the Hierarchy window . The model willbe added to the Scene in position (0, 0, 0).By default, you dont have any Scene in the Project window and a new, unsaved Scene is active. Youcould also drag and drop the model node directly in the Scene window. In that case, you dont have aprecise control of the position where the model is added to the Scene. Click the model instance nodein the Hierarchy window and adjust the Position in the Transform section of the Inspector window.By default, Unity applies a rotation that gives your model a different orientation than the one it has inÜrban PAD. To restore the original orientation, input the following values for the Rotation in theTransform section of the Inspector window: (-90, 0, 0). For more details on this problem, please seethose two links:  fbx importer correct orientation  3Ds max to Unity: scene rotated by 180 degreePlease note that when importing an entire city the orientation is automatically set to correctvalues by our script. 6
  7. 7. Add transparencyTransparency can’t be automatically managed by the import script. If one of your materials referencestextures with transparent parts, then you have to select the material node and change the shader tothe equivalent transparent shader in the Inspector window:  Bumped Diffuse --> Transparent/Bumped Diffuse 1  Gamr7/Diffuse Normal Specular --> Transparent/Gamr7/Diffuse Normal Specular 2 7
  8. 8. 3.2 Import city at onceHow it worksAs we said before, G7_UnityImport.js is called automatically during the import process. This script willcreate a Unity prefab and use multi_export_global_file.xml to load and set each individual part of thecity at its own place, as a child of the prefab.Import an entire cityThe process is simple: copy your city folder in the Assets folder of your Unity project directory. Itshould now look something like this: Unity Project |__ Assets |__ Editor |__ G7_UnityImport.js |__ Shaders |__ G7_DiffuseNormalSpecular.shader |__ G7_Alpha-DiffuseNormalSpecular.shader |__ My exported city folderReturn to Unity, wait for it to load the new assets and you will see a prefab with the same name asyour imported citys folder in the Hierarchy Window 1.Note that this prefab is available in the project panel, in your citys folder 1. 8
  9. 9. You can even import many cities this way at one time. A prefab will be created for each city you haveimported.3.3 Export a PackageTo export a package, in order to sell it on the Assets Store for instance, use the Assets->Export packagecommand 1. An Exporting package window will pop up, letting you select which elements you want toinclude in the package. After clicking Export, all these elements will be bundled into a uniqueunitypackage file.The project hierarchy is saved within the package file and you can re-import it in any Unity projectusing the Assets -> Import package command 1. 9
  10. 10. 4 Frequently Asked Question4.1 Can I sell the building/city I created with Ürban PAD on the UnityAsset Store?Yes, there are no limitations to using Ürban PAD to create your Asset Store assets. You can learn aboutUnity’s Asset Store limitations here : submit your content to the assets store.4.2 Can I export directly into Unity Asset folder?Yes, you can export your data directly to your Unity project folder, and wherever you want. You justhave to use the folder selector 1 in the export options of Ürban PAD. 10
  11. 11. 4.3 Can I use Ürban PAD-integrated Substances in Unity?We will add this possibility in a future version of Ürban PAD.4.4 What about LOD?We have developed a quick LOD system for Ürban PAD assets. Let’s have a look here:<Unity_LOD_doc>4.4 What about colliders and collisions?Keep an eye on upcoming versions of Ürban PAD; these features will be released soon. 11