Is there a way to limit the shape that emits particles to something other than a rectangle?

[SvenTheMerciless (Slippery Sven)]

I want to have a particle emitter in the shape of a triangle emit particles only from the triangle and not from the rest of the rectangle that the triangle is in.

I can not find a way to have particles emit from only the triangle part and not the ‘empty’ spaces around the triangle.

I have searched this forum and googled the issue, but have not found discussion of this problem. I have tested all available shapes and was unable to find a way to get the result that I am looking for.

I am attaching a screen capture to illustrate what I am getting. Note that the sides of the triangle that are ‘empty space’ are part of the rectangle which contains the triangle are emitting particles in addition to the triangle. I am trying to disable this feature.

[RMofSBI]

Create the triangles with wedges and make them flat… that way the emitter is restrained to the edges of the wedge shape.

[SvenTheMerciless (Slippery Sven)]

Same result occurs with wedges; the ‘invisible’ side of the wedge emits particles too.