This guide is intended as a complete beginner's guide to recoloring assets for Cities: Skylines. If you have any experience with making assets there'll be stuff here you already know. I will also only look at the steps needed from exporting a model to importing it again - for a more in depth guide to asset creation I suggest starting here: Texturing & Asset Creation 101.

You do not need any experience with 3D modelling as I'll take you through the steps of preparing the model for import using Blender.

If you're planning on uploading a recolor of someone elses asset when you're done, I suggest asking for permission before you start. If they say no, you won't waste time on something which will be removed from the workshop. And if they say yes you might get some of the original files making your work easier. ;)

There's a few things you need in order to do this

• ModTools
  
• Blender[www.blender.org] or another 3D editing software - I will be using Blender in this guide.
  
• An imagine editing software - I'd suggest GIMP[www.gimp.org] or similar.

• Before loading up a city, make sure ModTools is enabled in the content manager
  
• Find the building, vehicle etc. you want to recolor - you can do this in a city or in the asset editor
  
• Select the building in your city and click the "Find in SceneExplorer" or hit ctrl + E in the asset editor.
  
  
  
• Click "Preview" and find "Dump mesh+texture" and close the preview window
  
  
  
• Click "Preview LOD" and find "Dump mesh+texture" again
  
• The files have now been dumped to the import floder - typically C:\Users\YourUserName\AppData\Local\Colossal Order\Cities_Skylines\Addons\Import

The exported model is an .obj file and we want a .fbx when importing into Cities: Skylines. I'll take you through the steps to convert it using Blender. We'll also have to mirror it as it has been mirrored by the export.

• Open Blender, right-click on the cube and hit X to delete it.
  
• In Files find Import and choose Wavefront (.obj), then navigate to where you have the .obj file we just exported from the game, select it and import it.
  
• Select the model in Blender by right-clicking on it.
  
• Go into edit mode (you can use the Tab button for this).
  
• Select everything by hitting A (if it isn't already selected).
  
• Hit ctrl + M, then X and Enter - this mirrors the model, so it's correct again.
  
• Hit W and find Flip Normals on the list.
  
• Go back to object mode (Tab again).
  
• Make sure the model is selected (orange outline).
  
• In Files find Export and choose FBX (.fbx).
  
• Make sure all the export settings match those in the picture below (note the 4 tabs "Main", "Geometrie", "Amatures" and "Animation")

Thanks to BloodyPenguin ModTools now exports the textures in the right way, so there's less editing to do. :)

Here's a quick explanation of the different textures.

• Diffuse texture (assetname_d.png) - this is the basic texture with the colors and whatever might be painted on the model.
  
• Specular texture (assetname_s.png) - this is a greyscale texture determining how shiny/reflective the model is. White is very reflective and black doesn't reflect light at all.
  
• Normal texture (assetname_n.png) - this adds shadowing to the model making it look more detailed. A good example is buildings with brick, as we can't model each brick.
  
• Illumination texture (assetname_i.png) - another greyscale texture used to add light to the model. This one works very differently on buildings and vehicles.
  
• Alpha texture (assetname_a.png) - often just a black and white texture making the model transparent at places. Black is transparent, white isn't. Only decals can be semi-transparent - everything else will either be solid or transparent.
  
• Color variations (assetname_c.png) - a greyscale texture applying color variations to the model. White areas will have the color variation applied, black will not. You can use grey to have a little of the color variation applied.

If you're just doing a simple recolor (like changing the brand on a truck) all you'll need to edit is the diffuse texture. I suggest saving it as a new file, so you have the original in case you regret making some changes.

Note that Cities: Skylines is very bright and colorful, so colors might look different in the game than you planned on. I usually turn the saturation and lightness down by 50% on the finished texture, which makes the colors look more like I expect them to when it's imported into the game.

Time to bring everything back into the game! All files go in the import folder normally found here: C:\Users\YourUserName\AppData\Local\Colossal Order\Cities_Skylines\Addons\Import

The naming of the files is very important for Cities: Skylines to understand what is what. Here's an example of how things should be named.

• nameofthefile.fbx (this is the model itself we exported from blender)
  
• nameofthefile_LOD.fbx (the LOD model we exported from blender - it's important LOD is in capitals here)
  
• nameofthefile_d.png (these are the textures for the model, see the previous section for all the different types and the corresponding letters)
  
• nameofthefile_lod_d.png (these are the textures for the LOD, note that for the texture LOD is in lower case letters. Otherwise they're named the same way as the main textures).

If you leave out a LOD model and/or LOD textures the game will generate it's own. Sometimes the result is good, sometimes it's bad. Generally round or complex structures should have custom LODs, where simple block models can have good auto-generated ones. Make sure you check the LOD by either setting the level of detail low (so it shows the LOD early - remember to change it back!) or use the LOD Toggler mod and the CTRL + Alt + '.' key combo to display the LOD at any distance.

When everything is named and ready open up the game, select Editors in the menu, then Assets and then New Asset. When selecting a template I'd suggest you use whatever you are making a recolor off - you can always adjust the stats if you'd like later.

After selecting a template click Continue and find your model in the list. You'll see a little preview picture of the model. Hit Continue to bring it into the game - it might take a moment as the game compresses the textures. If you're not happy with something, edit the texture and repeat the process.

When you're happy with the look, save it and restart the game to test it out.


Toubleshooting
If you're having problems with importing the model, here are a few things to check and try.

• Turn of mods and assets you don't need for this
  
• Check all the names are correct
  
• Export the model again from Blender making sure you only have it selected and all the export options are correct

Now you're done and have hopefully had a chance to test everything works as it should. You might have made this recolor just for you, but you might also want to share it on the workshop. To do so find it in the content manager and click "Share". You can add a description and more pictures when it's uploaded.

If you have made a recolor of someone elses asset, make sure you ask for permission before sharing!

Ofc there's also the chance the creator isn't active anymore and you'll never get an answer. In that case I recommend you credit the original creator and give a link to the original asset, but give them a chance to respond first. :)