How to Build - A Next-Gen Game Carby Valentin Nadolu


Using the above rules, here is how the wheel looks. The continuous edges are hard and the dotted line ones are soft. This view mode can be activated by shift right-clicking on the object and selecting Soften/Harden Edge->Toggle Soft Edge Display.



I recommend setting up the normals before optimizing the geometry. This way you can take shading into account when the polygon reduction is done. As the hard/soft edge setting in reversible, it is easier to change edges from hard to soft or vice-versa than to reduce the entire mesh with all the edges set to hard only to realize that once the normals are set, some areas require extra polygons. Next, some images that show the way the normals are set on the car’s body:






If the high-res geometry had intersections, it is preferable that the ingame version has none. Partially occluded polygons will most likely lead to artifacts in the game’s engine. Topology has to be redone in certain areas, and fully occluded faces can be deleted to avoid rendering artifacts.



Now comes the polygon reduction part. In the following images are basic descriptions of the most common polygon reduction methods and some areas where they can be applied.

1. Select Edge Ring and Collapse



2. Select Edge Loop and Delete Edge



The borders of the low-res model are very important. They have to match the high-res geometry very closely so that baking the textures will not result in “blank spots” on the normal maps because of improper overlap. The white wireframe object in the next image is the high-res model without smooth. The green wireframe object is the low-res. As you can see, the two shapes might not be identical, but the borders are very close to each other.



Moving on to the wheel wells, the quickest way to make them is to select the border of the wheel well and to extrude it in.