I have 7 separated objects with different UV maps, but since i want to export to unity i would like to join all the UV in order to reduce draw calls keeping the objects separated. Is it possible?
You can't combine the UV maps of multipe objects in Blender. Officialy the the TextureAtlas plugin only supports lightmaps (the link could be outdated).
But wait Gleb Alexandrov made a promising tutorial:
John Carmack from id Software used megatexture. You use megatexture.
Related Unity Links:
Today you can use the "Smart UV Project" function in Blender.
- Select all objects, press spacebar and type in "Smart".
- Then activate the UV arrangement by clicking on "Smart UV Project" in the search results.
Blender will handle all selected objects like they were one single mesh and arrange the UVs in this way.
A very useful tool for making texture atlases for multiple separate objects is to check "Draw other objects" in the settings panel (T) in the UV/image editor window:
This will show the UV maps of every object you have selected when in edit mode, so you can manually scale and place all the UVs into the same texture space.