DevBlog: Rims

Among the highlights of Nitro Nation 4.0 is a new collection of rims licensed from TEC Speedwheels. As with every licensed product, our main challenge is to maintain consistency with the real counterpart as well as the rest of the game. Let’s take a look at what it takes to bring a new wheel to life.

Everything begins with a reference photo:


In this example we’re looking at a two-tone wheel called GT4. This is an interesting flat design with contrasting bright spokes and gunmetal grey rim.

A 3D artist models an element of the wheel over the photograph, following the original lines closely. When an element is ready, it is copied and rotated to produce a perfectly symmetrical model:


While this wheel might appear relatively simple with its strict geometry, it is composed of 2500 individual triangles!

The metal texture is simulated using a bunch of scripts called shaders. As the name suggests, the mainly describe how any material in the games responds to light and shade, including its reflective properties. Most shaders look plain and boring in the modeling software, but they come to life in the game where they correctly reflect light and even the surrounding scenery.


Now let’s see how the finished wheels looks in the game:



Note how the plain white and grey parts have turned into reflective surfaces – just as planned.

There’s one step to complete before we can take the new wheels to the track. Nitro Nation uses a special, simplified version of each wheel to improve framerates during the race:


Compared to the original wheel, this low-detail version uses 86% less triangles – and device resources. At high speed it’s hard to see the difference:


But it’s much better for your phone :)