The amount of polygons a game model has should be limited as much as practically possible, to help maximise the games performance. There is no exact poly count to use however the below factors should be considered.
- How much detail is required
- Is the model going to be animated
- How many models will be rendered at once
- Will there be multiplayer
- Target game platform
- How prominent is the model
- Type of textures used
- Other effects in the game
Important Note on Polys Counts
It is important to preface this article by defining what a poly is when it comes to Game Engines.
In some modelling applications ploy count is determined by the number of Tris, Quads and NGons. However most game engines will triangulate your mesh. This means any quads are split into two triangles. This may double the amount of polys modelling software might quote.
Poly Counts to Give Some Context
To give some context to this article here are some reasonable ploy counts. They are very loose and in by no way standard but I think it is essential to conceptualising general numbers. These very much depend on the factors outlined in this article it. They could be a lot more or a lot less but I’m simply trying to outline we are not talking about millions
| Model Type | PC, PS & XBOX | Mobile |
| Character | 10,000 – 100,000 | 1,000 – 10,000 |
| Game Props | 1,000 – 20,000 | 100 – 2,000 |
Why is it Important to Limit the Amount of Polys
For a computer to render a poly on a screen it requires resources from the computer to do so. Not only does it have to render the poly it has to do so over and over several times a second. The burden on the computer for this is very minimal for a single poly. However when it gets to thousands or millions of polys it gets quite substantial.
The need to limit this on a powerful computer is somewhat reduced due to its larger processing power. However this does not mean it is not important. Limiting polys can assist with ensuring players of your game can run it on a lower speced computer (Increasing your Target Audience). Also Players with powerful computers can run the game at a higher FPS (Frames Per Second).
The trend of having the game work across different platforms may also push for careful use of polys. This means its becoming more essential to maximise the games performance as consoles or mobile have more limitations.
Recent updates to Unreal Engine have made poly count somewhat less important with the introduction of Nanite. I’ve done some testing with some interesting results I recommend you check out this article I wrote on this here.
How Detailed is the Model
The amount of detail the model has is probably one of the biggest driving factors to poly count.
Lets for example compare a box to a tree. To make a box you could quite easily get away with than very few polys than you would a tree. The more different shapes the model has the more polys it would take to create.
When modelling particularly for games, fine detail can be achieved without adding extra polys. The use of normal maps can greatly help with this. It allows you to fake detail by manipulating the light. I strongly recommend researching this if are unclear how this works. If your a nerd like me you may find it interesting. Its an ingenious solution to this problem.
Is the Model Going to be Animated
If a model is likely to need to be animated or deformed this should be taken into consideration when limiting your polys. If a model is going to need to change shape or bend in a specific way, having some extra polys available will assist with unexpected results.
Below is an example of what is meant by this, as you can see without proper amount of polys available the model flattens instead of bends like desired.
How Many Models Will Be Rendered at Once
The amount of models that are going to be rendered at once will affect the decisions you make in regards to poly count. Is the player going to see a vast environment or is it only going to be a room. The amount of models required for a vast environment compared to a room is considerable.
With a room you have a lot less models to render so you may wish to have higher poly models with more detail.
With an environment there are a lot more models to render so you will have to compromise on poly count. A common method to combat this it to employ Levels of Detail (LOD). This is where the models get more detail or polys the closer they come to the camera.
Will there be Multiplayer
Multiplayer can play a huge role in limiting your poly count as there are now additional things in play to contend with. You now have a server that needs to be able to keep updated with the game state. The more computationally heavy the game is the slower it may run.
You also now introduce several other players in the mix. Meaning additional models not only characters but any models that may be included with each player. This includes gear and projectiles. It can very quickly add up!!
Target Game Platform
The platform you aim to release the game on is important as your choice can affect the number of polys of your model.
If you choose to only release on PC you have a fair bit of room, as they have the highest processing power. When it comes to systems such as PS or Xbox there is still a lot of room, but less than a computer. Mobile devices or a Switch for instance have considerable less power, so careful decisions need to be made when choosing poly counts for these platforms.
Many games these days are releasing across platforms . If this is the plan than from the start you should consider reducing polys. This is preferable to reducing them for each system increasing the amount of rework and large decreases in quality across systems.
How Prominent is the Model
How prominent the model is should be a deciding factor in poly count. If a model is frequently close to the camera for example a character, then you may want to increase the poly count to avoid noticeable blockiness.
If a model is going to be far away from the camera a player is unlikely to notice any imperfections.
Using different Levels of Detail can assist with this. Once the model is closer to the camera it is replaced with the higher poly version. This helps to reduce the amount of Polys at any given time and not impacting the players experience
Type of Textures Used on The Model
The type of textures used on the model will be one of the biggest factors in your decision. For example, if you are only looking to use only a color map then all the finer details may need to be made using additional polys. If you are using a normal map as well you would be able to fake the details.
The use of texture maps can greatly increase the game however this is another choice that can affect the games performance. There is a trade off between the use of extra polys and using texture maps. I would suggest reading another article of What Game texture Resolutions Should you Use.
Other Effects in the Game
Other resource intensive functions your game uses should be considered. For example intensive functions such as complex lighting and heavy use of VFX can greatly affect what is possible to be rendered on the screen at any given time.
A trade off has to be struck and recognising all these effects can have a heavy toll on the game performance.
Suggested Workflow
From my experience I always aim for the lowest possible poly count. I take advantage of texture maps such as a normal map for finer detail. If possible go into the whole process with some guidelines in place.
When displaying large amount of models on the screen at any given time utilising LOD’s can be useful. However this can be a time intensive task as it involves possibly retopologizing various versions of the same model various times.
It is important to note that there is no point putting in excessive amounts of time reducing poly count if it is going to have an imperceptible difference to your games performance. Nothing slows progress and kills motivation like perfectionism.