Retopology for game models

evermotion

Hello I'm quite new here and a noob at game models. I'm more a general media modeller.
I wonder if game models need a totally different approach to retopology, uvmapping, texturing. I have sculpted an organic ship and this will be for a low poly mobile game. I need to retopologize this model and not sure if the cylinders should be a separate mesh or it has to be one piece with the main body. If this was for video or stills I would just separate it. For games I have no idea about the logic yet if this will be ok in game engines. Any advice appreciated.

Heres the ship

Eric Chadwick

Depends if you are going to use normal maps or not. Normal mapping works better with good topology, to avoid seams. See this thread: Understanding averaged normals and ray projection/Who put waviness in my normal map?

Also if the model is going to be deformed, like an animated character with smoothly-bending limbs, then you need good edge loops in the topology, to support that bending. See: http://wiki.polycount.com/CategoryTopology
http://wiki.polycount.com/ReTopologyModeling

But in your case, if you're not using animated-deformation on the model, you could simply use an automated decimation tool, like Meshlab.
http://wiki.polycount.com/CategoryTools#Decimation_Software
It will make what is often called "triangle soup", as in no edge-loops, just a sea of triangles when you look at the wireframe. But this is often good enough, and a big time-saver.

evermotion

Thanks for the tips. I didn't know its ok to autoretopo game assets. This ship will not deform so I guess I should try that.
I manually retopoed and uv'd one of the ships. After reading some forum posts, wikis and tuts I created the retopo like this and uvmapped along edges I want to be hard.
I wonder if mirrored uv's are ok for game engines?
I will paint this with 3dcoat and also do the normal maps there.

bacteria

Mirrored UV's are fine, but I would mirror only wings and leave middle section as one piece. Another thing is that your topology seems to be dense if this one is for mobile devices

evermotion

Thanks. Whats the logic of leaving the middle section as one piece? I'm just starting so any tips on that would help.
I thought it was very low already. Less than 1k polys.

bacteria

if you mirror in the middle it may be very noticeable that texture was mirrored , any scratches or dirt will look like roshak test. I rather make it unique for left nad right side. Of course it's not a rule. Other thing is that sometimes you may get bad looking seam in the middle, depending on map you bake or shader you use in engine.