Today I want to take you through a simple tutorial about the specifics of modeling for video games. How is modeling for games different from modeling for example an animated movie? The main difference is the amount of polygons that are used in the models. While modeling for games every 3D artist has to keep in mind that the game engine will have to render up to 40 or 60 frames per second in real-time for a game to run smoothly. This means all geometry, textures, animation, sound, effects, lighting and controller inputs are being processed in real-time. That is a serious task for a computer that’s why there shouldn’t be one wasted polygon in a 3D model.
To better determine the amount of polygons you’re going to use on a model you have to ask yourself:
- how big the object is going to be;
- how close the player will be able to see the object;
- will the player be able to see all sides of the object;
- can the smaller details be made in the texture map or normal map.
In this tutorial I am using 3Ds MAX and I recommend to use 3Ds MAX because of all the tools and shortcuts I will be using. But if you feel more comfortable with some other 3D modeling software then go ahead.
Here is the scene file. Download it, open it and we can start.
In this tutorial we will work with a 3D modeled room where I have created a lot of unnecessary polygons. We will go over every model and delete all the wasted polygons. The main goal of polygon reduction is to get rid of all the unnecessary polygons but keep the overall shape of the models. Once you learn how to reduce polygons you will be able to model more efficiently.
Image 1
Image 2
In the image above you can see the scene we will be working with. Take a good look at it and you already can notice all those edges along the walls that are completely unnecessary. There is a polygon counter enabled in the upper left corner (in 3Ds MAX it can be enabled using keyboard shortcut 7) where you can see that 737 polygons are used in this scene. That’s a fairly high number for this small and very simple scene.
Image 3
First thing we will do is hide everything but the room itself (you can do that by selecting the model, right-clicking and selecting hide unselected or using keyboard shortcut alt+q while the object is selected). Now you can use modify panel to get rid of all the extra edges. You can simply use Target weld option and keep welding the extra vertices or you can use constraints to combine the edges. It is done by selecting edge loop just like you can see in image 2, then enabling edge constraint (image 3) and move the whole loop to the corner. When the vertices in the corner overlap you can use weld tool to combine them.
Why do the room’s walls appear transparent? It’s called Backfase culling and can be enabled by right-clicking on the object and selecting Object properties. In the checklist you will be able to find Backfase cull.
While reducing polygons you have to be patient and careful, take as much time as you need to find all the polygons that can be reduced. In Image 4 you can see polygons from under the window this edge cannot be removed with techniques described above.
Image 4
Select the polygons as in Image 4, in the modify panel find the tool detach. The popout window will ask you to choose between detaching as element or object – choose deatach as element. Now you can select the diagonal edge and in the modify panel choose remove (don’t hit delete – that will delete the polygons around the edge and we don’t want to do that). This technique you can use in other places where needed. Work on your model until it looks like Image 5 below.
Image 5
Avoid polygons that have more than 4 sides. This will cause messy triangulation. You can check that using Graphite Modelling tools (3Ds MAX 2010 and above). In polygon modifying mode choose Selection panel and the very last option By numeric.
