Retopology - gamedev workflow, uv, tris, cycles

Cirmius

Hi!

Sorry if the thread title is too general, but I have a few problems, that shouldn't be that difficult (well, for me they are XD)

I made a deer skull in Zbrush and retopologized it on the blender. As I thought the horns were the most problematic. The first question is simple, but I couldn't find answer anywhere.

What's the workflow for the things like deer horns, which are pointed on the end? You can't avoid tris there. I made a loop cut on the end of each horn, but I am not sure if this is the right thing to do in gamedev workflow. (the loop is selected on the screen)

The second question is about Cycles itself. I noticed that the engine have problems with low poly model that has a normal map plugged in. When I put the same low poly models with normal maps on the other engines (Unreal engine, Eevee) I don't see any artifacts. Using multires on Cycles make the problem gone, but I don't if this is cheating when you want to be a 3d artist in gamedev :P Screenshot below shows the difference. Just tell me if my way of thinking is wrong.

Eevee first, the second is Cycles of course.

Maybe the problem lies on my retopology? Of course I will handle every kind of criticism

Also:

Should I square this UV in gamedev workflow? I heard that color grid mapping is important, but not stretched UV is even more imortant :P

birb

I'm sure someone more knowledgeable will come along with a good answer about the topology, but keep in mind inside game engines everything is a tris. Technically even in Blender meshes will be triangulated for displaying. Don't be too afraid of triangles, squares are good and subdiv's best friends, but you'll have to triangulate that mesh for baking and exporting. The questions here are if it's shaded correctly, if it deforms correctly when—if—animated, and if you have long thin triangles.

About the normal map, I suspect you're using a -Y one. Blender uses +Y. Flip the Y channel; the fastest way is to invert the Green in a RGB Curves node.

kanga

One of the nice things about retopoing a highpoly for games is not having to worry about tris. You can use them to optimize your mesh freely. Using quads where possible means you can edit the lowpoly mesh quickly when the art director brings in changes. If you import your game mesh into unreal for example, it gets triangulated anyhow. Whether your retopology on this mesh is good or not depends on how it will be used in a game. If this is just a supporting prop then the mesh could be optimized further. There are loads of threads here dealing with retopoloy and more detailed information in the polycount wiki.

If you are baking in Blender then its pretty easy to see if your mesh is working or not. So do that and then examine the mesh for artifacts and fix them. Just some general stuff:

• Avoid long polys (quad or tri)  as they produce artifacts.
•  Fix twisted polys by connecting verts to break up quads where necessary.
• Make sure your low poly penetrates the high poly surface as evenly as you can. So curved surfaces need more edges and flatter surfaces can be lower in resolution.
  
  I wouldn't worry too much about using cycles to render your lowpoly as it is intended as a game mesh. That's just personal though.