Decimated Mesh vs Clean Mesh

rayle1112

I was told that decimated mesh is bad for in-game performance. I used to use Zbrush decimation tool for hard surface stuff to save time but I got complained. He said the game engine (we are using UE4) will take more time to calculate meshes with bad topology. Is it true? As I know there are a lot of people are using this method for hard surface stuff like rock to save retopology time. 

JedTheKrampus

Topology is only really important for things that deform. For things that don't it doesn't matter as much, as long you mostly avoid long, skinny triangles and tiny triangles. The ideal performance situation for rasterizers is that the triangle covers an entire 2x2 pixel block. I find that usually decimated meshes capture forms better with fewer polygons (as long as there aren't too many fiddly, small details in the highpoly version), but you have to watch out for tiny or long triangles or you'll probably run into problems eventually.