Better Upgrade Mod: A fix for a broken mechanic

[boformer 3,169]

My newest project is a mod that allows growable buildings to exist on multiple (wealth) levels. To understand why this mod is necessary, a short explanation of Cities: Skylines' leveling system:

When an empty area is assigned a zone type, buildings gradually start to fill it. All of these initial buildings are "level 1" buildings.
Buildings will upgrade to the next level when certain requirements are met (Land value, Education Level, Service coverage).

Every growable asset (vanilla and workshop) is only assigned to one of these levels. When a building upgrades, it will be replaced with a completely different asset.

That's quite unrealistic, especially for high-density buildings:

Year 1: Level 1 Skyscraper built.
Year 5: Building demolished. Level 2 Skyscraper built on same plot.
Year: 11: Building demolished. Level 3 Skyscraper built on same plot.
...

You can fix this by uploading one building multiple times to the workshop, with different levels.
Issues:

• There is still no guarantee that a building upgrades to the duplicated higher-level version
• For every version of the asset, a separate model and texture is loaded into memory

 

Solution: The Better Upgrade Mod

Asset Duplication

My mod hooks into the asset loading process and duplicates growable assets. The copy still uses the same texture and mesh, so it will not take up additional memory space.

Asset Creators can prepare their asset by bundling a simple XML file with their assets (format not final):

The can also duplicate vanilla buildings. There is a separate configuration in the Skylines Installation directory which can be edited by the player.

Upgrade Control

The mod also hooks into the upgrading system and forces the building to upgrade to the asset specified in the configuration.

Other Possible Features

I'm not sure if I want to implement these. Feedback is appreciated:

• Create asset copies with a different zone type (e.g. a residential and a commercial version)
• Control which props show up in which version of the asset
• I also thought about merging this mod with the Building Themes mod

Compatibility with the vanilla game

Assets with a bundled XML file are still compatible with the vanilla game.

When you load a city without the mod, the modded buildings will just disappear.

Development Progress

The mod is still in early development. What works right now:

• User configuration in Skylines installation directory
• Duplication of the assets (based on configuration)

After that I will modify the update mechanism. After that I will create the system that loads the configuration bundled with workshop assets.

 

Asset duplication can be seen in this picture. All of these houses use the same mesh and texture:

  Edited July 3, 2015 by schmidtbochum  

[Turjan 1,048]

This sounds good . Anything that helps with memory management is a step into the right direction.

Not exactly related, but did anyone check whether there's a (speed) difference in loading items from the local asset library or the workshop? This game would possibly also benefit from some kind of "dat packer" which helped with loading times in SC4.

[boformer 3,169]

Nice work as always man!

Have you figured out a way to store the lot information from saved games? 

If you've managed to hook into the asset loading process, have you bypassed the need to reassign the lots their original buidlinginfo object on save?

Right now I am just duplicating the BuildingInfo on startup (see here and here). I am not reassigning the original info on save. I figured out that It would be too hacky (see Spoiler).

That's the reason why buildings will just disappear when you start the game without the mod.

Many parts of the code could be re-used for a Ploppable RCI mod.

The only reference to a BuildingInfo (so also the AI) of a building instance is Building.m_infoIndex

The easiest way to save a different infoIndex value is to detour BuildingManager.Data.Serialize(). Problem: This is a critical function that creates the save file data. If something goes wrong (e.g. new Skylines update), it might corrupt your save files.

 

This sounds good . Anything that helps with memory management is a step into the right direction.

Not exactly related, but did anyone check whether there's a (speed) difference in loading items from the local asset library or the workshop? This game would possibly also benefit from some kind of "dat packer" which helped with loading times in SC4.

This is an interesting post about Reverse Engineering the .crp file format. It is possible to bundle multiple assets in one file. I'm not sure if it would decrease loading times.

I think loading times are a smaller issue than ingame performance.

 

To both of you: Do you think it would be better to merge the functionality of this mod into the building themes mod?

[Turjan 1,048]

I don't really know. It sounds like a straightforward thing to do that makes sense and speaks to my sense of convenience. My only hesitation would be what happens if CO breaks the mod with some update and you are not around anymore to fix it, which would give them the chance to only break one part and leave the other part usable. Not sure whether this argument makes sense.

[aubergine18 11]

For props it would be useful if there were three settings per prop:

• show - prop is used
• hide - prop is not used
• random - randomly chooses show or hide

In the screenshot earlier, the row of houses all have same stuff in their back yard making them look unrealistic. They could be set up like this:

Level 1:

• plant1: off
• plant2: off
• table: off

Level 2:

• plant1: off
• plant2: random
• table: off

Level 3:

• plant1: random
• plant2: random
• table: random

etc. Wouldn't be perfect but would make things look a bit better.

If you're able to do prop-related stuff, another useful thing would be to deal with the 'palm01' issue; there's a load of props from the bonus assets (botanical garden, dog home, etc) for people who preordered the game. Most other users obviously don't have those assets. It would be cool if there was someway to define groups of alternate assets, for example there would be a 'palm tree props' group that has several different palm trees in it, including palm01 but also some workshop props too. This could be used to a) use alternate prop if required prop not found, and b) add more variance to buildings... for example there could be a 'table and chairs props' group that lists several models depicting table and chairs. In the houses above it would mean you could get different tables/chairs in the back yards by selecting randomly from the prop group.

So the prop settings for buildings could then be extended to:

• show - prop is used
• hide - prop is not used
• random - randomly chooses show or hide
• <propname> - use named prop instead
• <propgroup> - use random prop from a prop group

Furthermore it would be nice to have ability to make certain props biome/theme dependent... There are lots of buildings with palm trees that obviously will look out of place on a grimy european or boreal map.

P.S. Sorry for rambling so much, I only just woke up lol.

[aubergine18 11]

> I think loading times are a smaller issue than ingame performance.

I think both are related. The big problem with loading times is that every single asset is being loaded, regardless of whether it's needed or not. Many users have hundreds, sometimes thousands, of assets subscribed = massively long load times, and excessive RAM consumption.

IMHO it would be great if game only loaded what's needed for the current save, plus some common items (roads, service buildings, etc). Things like uniques and monuments should be loaded on demand, only if they are needed on the map.

To deal with dynamic in-game loading of an asset a procedurally generated construction site could be placed where the building will spawn or where building is plopped. Asset and related stuff can then be loaded in low priority thread to minimise fps lag, and once loaded the construction site gets replaced with the building being constructed (scaffolding stuff).

For many users, particularly those with low-end systems, the bulk of lag comes from endless swapping to disk when moving round the map; if only required assets were loaded in to RAM there would be much less disk swapping.

[Azurespecter 506]

> I think loading times are a smaller issue than ingame performance.

I think both are related. The big problem with loading times is that every single asset is being loaded, regardless of whether it's needed or not. Many users have hundreds, sometimes thousands, of assets subscribed = massively long load times, and excessive RAM consumption.

IMHO it would be great if game only loaded what's needed for the current save, plus some common items (roads, service buildings, etc). Things like uniques and monuments should be loaded on demand, only if they are needed on the map.

To deal with dynamic in-game loading of an asset a procedurally generated construction site could be placed where the building will spawn or where building is plopped. Asset and related stuff can then be loaded in low priority thread to minimise fps lag, and once loaded the construction site gets replaced with the building being constructed (scaffolding stuff).

For many users, particularly those with low-end systems, the bulk of lag comes from endless swapping to disk when moving round the map; if only required assets were loaded in to RAM there would be much less disk swapping.

I'm taking this suggestion to CO when they get back from vacation. Perhaps there is a good reason for pre-loading it all, perhaps not =)

[Shroomblaze 320]

> I think loading times are a smaller issue than ingame performance.

I think both are related. The big problem with loading times is that every single asset is being loaded, regardless of whether it's needed or not. Many users have hundreds, sometimes thousands, of assets subscribed = massively long load times, and excessive RAM consumption.

IMHO it would be great if game only loaded what's needed for the current save, plus some common items (roads, service buildings, etc). Things like uniques and monuments should be loaded on demand, only if they are needed on the map.

To deal with dynamic in-game loading of an asset a procedurally generated construction site could be placed where the building will spawn or where building is plopped. Asset and related stuff can then be loaded in low priority thread to minimise fps lag, and once loaded the construction site gets replaced with the building being constructed (scaffolding stuff).

For many users, particularly those with low-end systems, the bulk of lag comes from endless swapping to disk when moving round the map; if only required assets were loaded in to RAM there would be much less disk swapping.

I'm taking this suggestion to CO when they get back from vacation. Perhaps there is a good reason for pre-loading it all, perhaps not =)

Did they really go on vacation right after a bug fix patch that has caused so many bugs?

[boformer 3,169]

Did they really go on vacation right after a bug fix patch that has caused so many bugs?

Bugs? It only caused broken mods, which can not really be prevented.

[Shroomblaze 320]

Did they really go on vacation right after a bug fix patch that has caused so many bugs?

Bugs? It only caused broken mods, which can not really be prevented.

There are a lot of bugs, not just broken mods, but broken assets. People having to reinstall the game and still not functioning right. Various other bugs as well that I'm just not going to go into detail about.

[Turjan 1,048]

There are a lot of bugs, not just broken mods, but broken assets. People having to reinstall the game and still not functioning right. Various other bugs as well that I'm just not going to go into detail about.

I still have some annoyances in my game. One thing is that the ingame menus don't show all assets anymore when I first click on them. They cut the last items off, like the line tool in the train tab or some schools in the education menu. I have to scroll back and forth several times, and sometimes they appear then (may be a mod issue though). Then I still get messages about missing objects. I guess I have to go through all my workshop subscriptions again...

Steam Workshop is super convenient. However, I had already several items go missing because authors pulled them or changed them. I'm thinking about backing up some of them. Can you actually find the local copies of the workshop items somewhere? I only found the stuff I changed, or they are in these sharedassets##.assets files.

[Shroomblaze 320]

There are a lot of bugs, not just broken mods, but broken assets. People having to reinstall the game and still not functioning right. Various other bugs as well that I'm just not going to go into detail about.

Can you actually find the local copies of the workshop items somewhere?

Yea, located in your steam folder...

 

G:\Steam\steamapps\workshop\content

[Turjan 1,048]

Ah, thanks. I was looking far too much down in the hierarchy. I have 2.13 GB at the moment, which isn't too bad. I will just back up the whole folder.

I would just transfer some of the mods to the "user" location, but that's on my C: drive where I hardly have any space.

Edit: given the large amount of empty folders, I seem to have tried out and discarded my share of mods. Anyway, all *.crp files backed up.

Edit 2: Sorry for the off-topic, but I guess reducing the amount of single files for themes like the Terraced Housing definitely also helps with this.

  Edited July 6, 2015 by Turjan  

[Azurespecter 506]

Did they really go on vacation right after a bug fix patch that has caused so many bugs?

Bugs? It only caused broken mods, which can not really be prevented.

There are a lot of bugs, not just broken mods, but broken assets. People having to reinstall the game and still not functioning right. Various other bugs as well that I'm just not going to go into detail about.

I check bug and technical problem reports daily, and I'm sure not seeing this multitude of bugs that were introduced from this latest patch. Actually, like 90% of the complaints are from Traffic++ users who don't realize that the author has been on vacation and hasn't updated the mod yet.

If you'll direct me to some of these assets that were broken by the patch, I'll see what can be done. But I've heard no reports thus far.

[Turjan 1,048]

It's probably hard to find those assets. Or it's something else. In my case, I just unsubscribed from or disabled a bunch of assets (buildings), and my problems are gone (I even added three mods). Of course, one possibility would be that there's a limit how many entries the menus can handle without glitching out.

In general, I agree though. My game glitched out after the patch hit (menu overlay views could not be deselected except by switching to area view), but in general, the issues were minor and mostly fixed themselves. I'm very cautious with vehicles though, which have the tendency to break the game if improperly switched out.

[boformer 3,169]

the only issue had was that my game was crashing all the time when going back to main menu.

 

solution:

Unsubscribe from all custom assets.

Go to the folder where the workshop files are located, search for *.crp

for some reason there were still a few .crp files in the folder (maybe ones that were deleted from the workshop?)

I deleted them, which solved the issue.

[Shroomblaze 320]

Did they really go on vacation right after a bug fix patch that has caused so many bugs?

Bugs? It only caused broken mods, which can not really be prevented.

There are a lot of bugs, not just broken mods, but broken assets. People having to reinstall the game and still not functioning right. Various other bugs as well that I'm just not going to go into detail about.

I check bug and technical problem reports daily, and I'm sure not seeing this multitude of bugs that were introduced from this latest patch. Actually, like 90% of the complaints are from Traffic++ users who don't realize that the author has been on vacation and hasn't updated the mod yet.

If you'll direct me to some of these assets that were broken by the patch, I'll see what can be done. But I've heard no reports thus far.

Well, I just see a lot of people complaining, but I guess I could be wrong about all the bug stuff. Anyways a lot of my assets were broken by the patch making people have issues with the asset editor. I started a thread about it. It's not a super big deal though, The assets still work fine in game, just people have to disable those assets to use the editor. Although someone said they did have an error in game with one of the cargo assets I uploaded today, he said he reverted back to an old save and everything was fine again though so who knows about that. I understand they went on vacation, it's well deserved I'm sure. Sorry for my original comment. 

https://forum.paradoxplaza.com/forum/index.php?threads/workshop-assets-are-not-loading-up-in-the-editor.867549/

[Turjan 1,048]

    solution:

Unsubscribe from all custom assets.

Well, yes, sure. That's what the doctor said on his recipe. The patch notes were clear on that point.

I guess most people just don't want to abandon a city they are currently building, and an "unsubscribe from all custom assets" is the nuclear option for some cities. It is clear that I disregarded this advice in order to see whether I can still play my city. Aside from a few hiccups, it worked relatively well.

Maybe, I should be more careful with the wording. There is a distinction between "breaking the game" and "breaking the city I currently work on".

[Ryno917 102]

I think this is a great idea!

Any chance at provisions for upgrading the building appearance? For instance, say you have a large level 2 house that looks like it was built in the 30s. Upgrades to level 3 and it gets a modern entranceway added to it. Upgrades to level 5 and now there's a large modern residential tower built out of it, but the original fascia of the building has been preserved. I'd love to see something like that be possible at some point. That kind of thing happens a lot in Toronto with some of our (few remaining) old buildings.

[boformer 3,169]

In that case it actually makes sense to have 2 different assets, and just specify in the config that asset A should upgrade to asset B

Little Progress Update:

I deciced to merge the mod with the building themes mod. Why? Because there was a conflict between the 2 mods. (and I want to force people to use my awesome theme mod!!!)

Right now I'm working on the search function that looks for BetterUpgrade.xml files bundled with assets. Maybe I will also add a way to specify upgrade information in a theme configuration (useful when the creators of the assets are inactive).

After that is finished, I will create MANY new building themes using the new functionality.

Who wants to help me to classify the assets (min/max level)?

  Edited July 7, 2015 by schmidtbochum  

[Dubai Skyscraper 129]

Little Progress Update:

I deciced to merge the mod with the building themes mod. Why? Because there was a conflict between the 2 mods. (and I want to force people to use my awesome theme mod!!!)

Right now I'm working on the search function that looks for BetterUpgrade.xml files bundled with assets. Maybe I will also add a way to specify upgrade information in a theme configuration (useful when the creators of the assets are inactive).

After that is finished, I will create MANY new building themes using the new functionality.

Who wants to help me to classify the assets (min/max level)?

I'd like to help.. if it doesn't take advanced programming skills or anything. How exactly can I contibute?

[wallacet 336]

In that case it actually makes sense to have 2 different assets, and just specify in the config that asset A should upgrade to asset B

Little Progress Update:

I deciced to merge the mod with the building themes mod. Why? Because there was a conflict between the 2 mods. (and I want to force people to use my awesome theme mod!!!)

Right now I'm working on the search function that looks for BetterUpgrade.xml files bundled with assets. Maybe I will also add a way to specify upgrade information in a theme configuration (useful when the creators of the assets are inactive).

After that is finished, I will create MANY new building themes using the new functionality.

Who wants to help me to classify the assets (min/max level)?

It would be really awesome to see modeling teams (similar to what we had with SC4) that are each dedicated to modeling buildings within a specific theme. One group does asian buildings, another American suburbs, etc. If I had more time on my hands, I would try to get the ball rolling on this, but alas, I travel a lot for work and hardly get time to model (being a desktop user doesn't work well for travel ).

 

Edit: This really is something I would like to see. If anyone decides to head something like this up, don't hesitate to let me know. I can't guarantee I would be able to contribute much, but I think dedicated "theme teams" would make this game a whole lot better.

  Edited July 7, 2015 by wallacet  

[boformer 3,169]

I'd like to help.. if it doesn't take advanced programming skills or anything. How exactly can I contibute?

You don't need any programming skills. Now that we can assign multiple levels to growables, I need help with the classification of the assets on the workshop and the compilation of the themes. Another point is quality control: I don't want to include buildings with a too high poly count (or missing LOD). All buildings have to be checked with Mesh Info before we add them to a theme.

For example, I would like to make a high-density new york theme. Feindbold released a collection of NY buildings, but not enough to create a theme ranging from Level1 to Level5. Also, many assets could be assigned to multiple levels (and maybe even different zone types - I'm working on that).

The theme only works correcly if there are buildings for all combinations of footprint size, level and corner type (Straight or corner):

Let's say there is a 4x4 L3 residential corner building. For it to appear, we also need a L2 and L1 building of the same size. We can either duplicate the asset with the mod to create a L1 and L2 version, or include a different asset in the theme.

Another point is variety: If there is only one L3 corner building, it will be the only building that you will see in corners when the district is stuck at level 3. That's why it might be better to create as many versions of the asset as possible.

For a luxury home, maybe L3, L4 and L5. For a low-wealth home, maybe L1, L2 and L3. For a medium-wealth home, maybe even L1 to L5.

It is important to know that a corner asset will never upgrade to a "straight" asset and vice versa.

Also important: A building that was duplicated by the mod will always upgrade to the cloned version. That means when you have a 4x4 corner building classified as L1, L2 and L3, and another 4x4 corner building classified as L2 only, that building will never show up. A solution would be to create an L1 clone of the second building, so both of them spawn initially.

You see how difficult it is to create a working theme. The easiest way is to create a table that contains all buildings, like this:

	4x4	4x4 (Corner)	2x4	2x4 (Corner)	...
L1	Building_A Building_B (L1 clone)	..	..
L2	Building_A (L2 clone) Building_B (L2 clone)	..	..
L3	Building_B Building_C (L3 clone) Building_D (L3 clone)	..	..
L4	Building_B (L4 clone) Building_C Building_D (L4 clone)	..	..
L5	Building_C (L5 clone) Building_D	..	..

All spaces need to be filled. You don't need assets of every footprint size, though it is good to have a variety of sizes. Especially small filler lots (2x4, 1x2) are important to fill the gaps between 2 randomly placed buildings.

It is also possible to create themes which only contain low-density buildings (L1 and L2), though it is not recommended. The problem is that it affects gameplay when there is no way to upgrade a building. Low-wealth homes will generate less taxes.

  Edited July 7, 2015 by schmidtbochum  

[Dubai Skyscraper 129]

If I understand this correctly then I see a huge flaw in all of this - having clones of the same asset on several levels is kind of breaking the purpose of levels. What do you want to achieve with this? Just having the same building but on a higher wealth level? Why? I'm confused 

[Dubai Skyscraper 129]

Hm, I'd rather have the same building spawn 50 times on level 1 than having higher level models spawn before their supposed wealth level is reached. Duplicating assets over one or more levels will increase diversity, but on cost of (visible) progress.

I mean, it is perfectly fine if you have actually different versions of a building, say a lvl 1 with 2 storeys, a lvl 2 with 5 storeys and so on. If the mod assigned these to each other so that one consecutively replaces the next is a great thing. Having duplicates spawn on levels they were not designed for on the other hand... I can't help but this breaks the entire mod for me.

  Edited July 7, 2015 by Dubai Skyscraper  

[boformer 3,169]

6 reasons why it is a good idea to duplicate assets:

• The game actually does the same thing: Just watch closely what happens when a European high-density building upgrades to the next level. There is a high chance that you will see the same building. Most european assets appear on all 5 levels. I guess it is the same for the international theme.
• The memory (RAM and VRAM) is limited: You can not load 1000 meshes with 1000 textures (not counting ploppable buildings). There is also a hardcoded asset limit.
• The amount of models needed to create a theme: It would take months to model enough buildings for one theme that just contains building of one zone type. Different plot sizes (e.g. 4x4, 3x3, 2x4, 2x2, 1x2), corner variants (straight, corner) and 3-5 wealth levels: 5x5x2 = 50 assets
• In most cases, you can not guess the level of a building by looking at it. Especially not when there are 5 levels. Maybe you can say "low-wealth" or "high-wealth", but that's it.
• The level up mechanic is not realistic. Let's say you get promoted and earn 500$ extra. Would you demolish your house to build a new better one? Or would you stay in your house?
• If we don't provide buildings for every wealth level, the economy of the game will break; Educated Citizens living in a low-wealth house that can not upgrade will not get a better job. You will not earn more taxes to pay for the university you built to educate your citizens...

 

[Dubai Skyscraper 129]

6 reasons why it is a good idea to duplicate assets:

• The game actually does the same thing: Just watch closely what happens when a European high-density building upgrades to the next level. There is a high chance that you will see the same building. Most european assets appear on all 5 levels. I guess it is the same for the international theme.
• The memory (RAM and VRAM) is limited: You can not load 1000 meshes with 1000 textures (not counting ploppable buildings). There is also a hardcoded asset limit.
• The amount of models needed to create a theme: It would take months to model enough buildings for one theme that just contains building of one zone type. Different plot sizes (e.g. 4x4, 3x3, 2x4, 2x2, 1x2), corner variants (straight, corner) and 3-5 wealth levels: 5x5x2 = 50 assets
• In most cases, you can not guess the level of a building by looking at it. Especially not when there are 5 levels. Maybe you can say "low-wealth" or "high-wealth", but that's it.
• The level up mechanic is not realistic. Let's say you get promoted and earn 500$ extra. Would you demolish your house to build a new better one? Or would you stay in your house?
• If we don't provide buildings for every wealth level, the economy of the game will break; Educated Citizens living in a low-wealth house that can not upgrade will not get a better job. You will not earn more taxes to pay for the university you built to educate your citizens...

 

1 - Right, I noticed it just today when I tried the Euro theme for the first time. I was pretty stunned (and disappointed). As for the international theme I have never noticed such behavior, or it happens extremely rarely.

2 - Sure the resources are limited, but not everyone plays on a low-end PC. I have 32GB RAM and a GTX 780, heck I want to make use of that  If there is an asset limit then I hope that will be changed one day. If enough people request it, we got a good chance for that.

3 - You got a point there. But I'd still not use this mod as long as there is at least one asset for each type(corner) and plot size.

4 - Eh, that goes for low density builings that do not exceed a couple of storeys. When I grow my high density districts I just love to follow the progress curve (especially on offices where it's a little tricky to reach level 3). As someone who models mostly fancy stuff of level 3 (5 for resi), I want to preserve this stuff for the highest level.

5 - Of course it's not realistic. It's a game after all. If you get promoted IRL and get a good raise of your salary you would not demolish your house... but probably move out. Most likely into a more fancy house in a new fancy district.

6 - We probably shouldn't make themes then that do not provide a sufficient amount of assets. And some themes should not level up at all. Think about the trailer park theme. What the hell is a lvl 5 trailer supposed to be? These should always stay at lvl 1 (2 at most) because no wealthy person would ever live in a trailer. Besides, if every person who attended an university would live in fancy highrises.. I'd be sooo happy

Now this was a lot of criticism. To put things right, I don't want to discourage you. After all you are doing an excellent modding job here! What I intend is to give you a critical reflection of it. And I'm hoping the building themes mod will also stay a standalone mod, or that there is an option to disable duplicated buildings. It is really awesome and I want to help you with the collections, as mentioned above.

[boformer 3,169]

 

These should always stay at lvl 1 (2 at most) because no wealthy person would ever live in a trailer. Besides, if every person who attended an university would live in fancy highrises.. I'd be sooo happy

Now this was a lot of criticism. To put things right, I don't want to discourage you. After all you are doing an excellent modding job here! What I intend is to give you a critical reflection of it. And I'm hoping the building themes mod will also stay a standalone mod, or that there is an option to disable duplicated buildings. It is really awesome and I want to help you with the collections, as mentioned above.

First of all, there will be a way to disable the duplication of buildings, although that might break some themes (e.g. when all level 1 buildings are duplicates of L2, nothing will grow).

I also don't want to create L5 Trailers. But look at the NY buildings: You will not see the difference between L1, L2 and L3

I know that reclassification of assets is a critical point. That's why I asked for help.

  Edited July 7, 2015 by schmidtbochum  

[Turjan 1,048]

• The game actually does the same thing: Just watch closely what happens when a European high-density building upgrades to the next level. There is a high chance that you will see the same building. Most european assets appear on all 5 levels. I guess it is the same for the international theme.
• ...
• In most cases, you can not guess the level of a building by looking at it. Especially not when there are 5 levels. Maybe you can say "low-wealth" or "high-wealth", but that's it.
• The level up mechanic is not realistic. Let's say you get promoted and earn 500$ extra. Would you demolish your house to build a new better one? Or would you stay in your house?
• ...

I agree with your general reasoning (RAM and hard-coded limit issues, game economy), so just comments here:

Actually, the international theme has mostly different buildings for all 5 levels (or 3 for CIO). I think there are some duplications in residential houses of levels 3 and 4, but most of the time, you can tell the exact level a building has just by looking at it.

Regarding what to do with a raise, the US answer would be to move to a new house. Anyway, in game terms, the model may stay the same but the lot changes. The model may also change by getting a nicer paint job, some fancier window clutter, a different store on the ground floor.

This means that I don't think the arguments I quoted are strong (the others of course still very much apply). However, this does not have much influence on the practicalities. I would probably use the following workaround: Differentiate between full themes (like "international" and "European"), add-on themes (like highrises that fit in "International" but are kept in "International Plus" for easy swapping in and out) and starter themes (a set of very few, low level generic buildings that help starting any add-on theme).

Of course, your method has the other advantage you mentioned. It will definitely be a boon to themes like the UK Terraced Housing one, to help keep these buildings alive without strangling your game. I could also think of a "slum" theme that is a slum in looks only but will still upgrade and pay taxes. There are some very nice mods with buildings for level 1 and level 2, but it's really hard to see those for more than a few minutes, because the game levels to level 3 if you throw as much as a fire station at the area and have police and schools somewhere else in the city, so it's still good.

[boformer 3,169]

progress update:

I'm working on the integration of the features into the Building Themes mod.

I am really proud of my code so far, though most of it is just a clean up of the existing code, to prepare it for the integration.

I think it will be done in a week.