Invisible objects for props and PO

This guide is intended to be a part of a larger one, and will be included in it, on how to make assets for Cities:Skylines - together with references to all that scant information created so far.

This part is published earlier because things included here I find easy for anyone to make, and also to give some inexperienced gamers some more information and help now.
This may also serve as the first step in creating assets for the game – something quick and easy.

Things that are not covered here are:
- modelling and modelling programs (I’m using Blender – I have to admit it’s not very intuitive but it’s the only one that is free of charge and can be bent to meet your needs ;) )
- graphic program – I think in this case even simple Windows’ paint should do – creating a black rectangle picture should be supported there… I’m hoping ;)

All that will be done in other parts of the guide.

Start here or skip it

An invisible asset is a very nice feature to add some functionality to props or procedural objects made for Cities:Skylines. Also it is absolutely easy to make one. Only thing you need to decide is: what functionality you want to add (and that’s most likely what you already know) and how to do it.
Such an object also uses game’s building limits – that’s the only downside here but in case where you are merging few props or, especially, procedural objects into one more … fancy one, bringing a functionality with just one building instead of 7 or 17 of them, is all that matters.

*Using Procedural Objects mod where you can change any building into something that C:S doesn't treat as a building and it does not count towards any limits, is a great help here.

Modelling

First step is go to Blender, create a mesh of as low poly as possibly (and no LOD is needed this time as the game will create exactly same model for you – this time it’s helpful) and that model would have to be a pyramid, if you have it as a square based one, merge its 2 neighbouring vertices (in whatever fashion you want – centre, last or to the first one), and remove its bottom face – you have a game asset that has 3 tris.


You don’t need to make a separate mesh for lod model but you do have to make that LOD model for the game as an fbx file otherwise the game will generate lod model with increased tris count from 3 to somewhere around 150 (unfortunately Mesh Info mod doesn’t seem to read model tris count properly anymore – it reads 9 tris for a model that has 3 tris – so I’m not really sure how many tris that game generated LOD model really has).

I had tried before to make a flat surface (triangle so it would have been just 1 tris) and it fell flat obviously ;) C:S didn’t want to read it for some reason, otherwise it would have been just 1 triangle object!

Now, export this triangle based pyramid from Blender to an fbx file that Asset Editor will read, in 2 versions:

- main mesh with a name, let’s say: pyramid
- lod mesh named in this fashion: pyramid_lod – no capitals, no space

In case you wanted to have more words in a name – that’s what I also wondered when I started making assets, fear not and make it as below:

- main mesh with a name, let’s say: my nEw pyramid
- lod mesh named in this fashion: my nEw pyramid_lod

The above example is with a random capital letter – hardly anyone does it, but if you do want to have capital letters, you have to name any other lod model or texture in the exactly same way (see below for textures).


For those who would like start learning more on modelling in Blender right now, refresh their knowledge or get some more tips (even from a basic guide) here is a guide I've found best for myself:

Complete Beginners Guide to Blender 2.8

It's for any Blender from 2.80 up to the current version, but not below. It is in 6 parts varying between 12 and 22 minutes.
Also, if you find any tutorials working better for you - let me know so I can include them in the main guide too.

Blender can be found here for manual download and update:

Blender website[www.blender.org] - including older versions

or you can have it from Steam Store too that will update everything automatically when you run steam client:

Steam Store - Blender - it is free of charge.

Invisibility now

Second step is to make as small as possible texture – I think 16*16 is the smallest you can get but it won’t matter, as even 128*128 won’t take much space – that is only one colour and it’s black.

And it’s not a diffuse map but an alpha map ( _a ) that will make your mesh invisible – add “_a” to the name of your texture (texture name must be same as the model name) and together with fbx file (your model done in Blender), import them to the C:S asset editor. You don’t need to make a diffuse map at all in this case.

How to make texture maps including alpha - check it here:

C:S wikipedia[skylines.paradoxwikis.com]

and here

Texturing & Asset Creation 101

Following our example for the fbs file, you have to name your texture exactly same as your model:
for the first example it would simply be:

- pyramid_a
- pyramid_lod_a

and for the second more complex name:

- my nEw pyramid_a
- my nEw pyramid_lod_a - make it for LOD model too otherwise your lod model will be visible in game when you zoom out, even as a small dot, anything that keeps popping out out of nowhere is a bit… funny at first but annoying later; a small bright-ish dot appearing all of the sudden when zooming out may not be your thing – if it’s hidden under a prop, that’s alright but sometimes you may need it without any props.

A function of your choice

Here is a choice and a decision to make… or just release all your ideas ;)

Do I want a park? A fishing harbour?

One would think you don’t need a mod for invisible fishing harbour… but you do actually. Have you noticed how far apart are its boats spawning points and paths? You can get them closer together (or even further apart)


and in few different shapes (you can bend or make turns in those paths) or directions.

(this one may actually not work as spawn points are not placed where paths are but I haven't tested it - let me know if you do and whether it works or not).

But few rules will apply (from my experience, test yourself, something may change in game mechanics by the time you read it):

- no more than one spawning and one despawning point – a big shame
- paths don’t seem to like crossover each other or overlay on top of each other – they may touch themselves slightly but that’s only up to a point, then the game will display an error (not a game breaking, but it won’t display it in the asset editor, only in game).
So anything like in the screenshot below, unfortunately will not work but will load into the game:



There are some old mods that you will need for introducing different functionalities – only some of them don’t work anymore, most of them still does, whether the last update was in 2016 or 2020, they still work.

Move It mod will be useful in few circumstances too. And I can definitely help finding any other that will help you. Also Avanya, our community ambassador, has got a vast knowledge of the workshop and mods on it, as well as some other modders – always worth checking with them.

The mod that will help you with fishing harbours - and is also visible in screenshots in this section of the guide, is

Advanced Building Editor by BloodyPenguin


So now just add your own values for things such as electricity and tourists and so on, in properties, take some screenshots and save your asset.

All steps here

Steps to be taken after creating the fbx models and alpha textures (more on that in Start Building part, or here: Texturing & Asset Creation 101)

- move (or rather copy and paste) all fbx and png files to the game’s Import folder:

On Windows it's in: %localappdata%\Colossal Order\Cities_Skylines\Addons\Import
(...\Users\****your user name folder****\AppData\Local\Colossal Order\Cities_Skylines\Addons\Import)

- run C:S (you may need to create a noWorkshop version if you have more than 1000 assets and mods, just to speed things up)

- start game’s Asset Editor

- choose a template for your asset (the original model with its own mechanics that you want to use, doesn’t need to be same size)

- scale it down or up so it says 1

- continue

- test your invisible model just in case by zooming out – not too far, just enough to still see that highlighted grid where your model is – if nothing appears there that means that your lod model works too

- take some screenshots of that “nothing” to speed things up when saving

- save it

That’s imported in the game now, you will find your crp model in this folder:
On Windows %localappdata%\Colossal Order\Cities_Skylines\Addons\Assets


And you can now also share your model with others on the workshop - just prepare some custom screenshots instead of using anything like this: