More emitter position modifiers (2d mesh? Rect? Cube?)

[Lubba-64]

Describe the solution you'd like
Box and Cube emitter areas, or just more options than a circle. potentially a mesh? or list of tris?

Describe why you want that solution. Is this related to a problem?
I want the emission area to cover just where my characters exist and not the area around them, having a more configurable area to spawn particles in is a good way to achieve this, and other particle systems support similar functionality.

Describe alternatives you've considered
For now since this is not urgent, I'm just going to use the circle emitter. I'm sure that other people have thought of this though.

I may come back and make a contribution here to get this implemented, since it doesn't seem like it would be impossible. although I have never tried to write shader code just like this crate does haha!

[djeedai]

So the general idea is we want to remove the various position and velocity init modifiers. Instead we want to add expressions that let you sample shapes randomly. After that you simply plug the expression into some SetAttributeModifier. That way we don't have to maintain every shape multiple times for position and velocity, and you can even reuse those expressions in other cases. But yes, otherwise agreed.

Note that the mesh one is quite a lot more complex because it's not analytical, and requires access to the mesh geometry.