So, I want to have a box that spawns particles all over the mesh (box goes on fire).
Importing a box I made in 3dsMax, editable poly exported to Unity as an FBX - and mesh particle emitter applied.
But the particles only emit from one side of the box.
If I create a box in unity with unity’s ‘create gameobject box’, and give it a mesh particle emitter, it spawns from all sides.
What’s unity’s beef with my boxes?
Any help appreciated.
does the box have correct normals? if they are incorrect (physically nonsense) physx will ignore them.
you can normally test that by telling unity to generate normals and tangets on the meshes import settings to ensure that fucked up exports from the modeller get brought in line with what they should be 
unity seems to have ‘generate normals and tangets’ on by default, and it still only spawns paticles on one side, even with calculate normals ticked/unticked. Still no joy.
Quick update - the problem of only emitting particles on one side was solved by having a single texture for the box (previously I had a different texture for each side of the box).
If anyone has a workaround to allow mesh particle emitter to work on objects with more than one texture let me know.
For now I guess I’ll just tool around with uv mapping on a larger texture.
For memory management, you will want only 1 texture anyway, just IMHO, although I am NOT a modeler, you do not want to see my models.
There is absolutely no good reason to have a separate texture for each side of a box. What you have there is a minimum of six separate draw calls just for a simple box.
Yea I know, I should know better, it was just a test using an old model - I’m a modeller/programmer half breed and sometimes I forget the simple things, still, problem solved!
I’ve had similar problems with my projectile collision hit effect (a prefab) only showing up on some of the surface faces of a 3ds imported mesh. I do not have any textures applied to the mesh atm. Perhaps this is the problem.
If you did need separate textures for each side of the box for some reason, then you would simply use one mesh for the particle emitter and a different one for the box.
–Eric