What is a best mapping practice on a performance level?

Development Rendering
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1

On many meshes I run into the problem where there’s a small detail I need to capture in a bake, like bolts or a handle on a door, but due to keeping all UV islands an equivalent size for pattern-overlay purposes, even if I make the map 4096x4096, that small detail just doesn’t get enough resolution.

A few ways I can think of to get around this:

  1. Move the tiny bits onto a new plane and use an alpha channel to define them. Then I can make that plane as large as I want in my UVs, with the consequence being that I’ll have to turn my material into a masked material just for that one section.
  2. Same as above, except instead of having that plane in the same map, I split it up into a new material. This way I won’t have to make the entire material masked when only one small part is necessary, but then it also increases draw calls (and forces me to manage two materials for the same model).
  3. Use a new UV channel for the pattern overlay–so one UV channel is for the normal map (resizing everything so that I can capture the required details), one for patterns, and one for the lightmap. I have no idea about the performance/size cost of multiple UV channels.

Which option would be the most optimal?

2
  1. You dont need to make a masked material, you could actually import a fairly small mask texture, and multiply it with your main texture to hide that part. then use a 2nd texture (for the details) and multiply that with an inverted version of your masked texture.

(with UDK | CroppedEmissiveAssistant can help)

  1. I would not suggest this.

3.Multiple UV channels is a very small cost unless you use more than 4-5, though ue4 can handle much more.

I would personally make the 2nd uv with additional details and either mask them in inside one shader, or multiply them in.

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Thanks for the input. The whole multiplication thing with way #1 sounds interesting, but I don’t understand exactly what’s going on even after checking out the link. Multiply the small mask texture with the main one to hide which part?

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I will see if I can make an example later today, just wanted to give you a headsup.