I think I have found a use for geometry shaders now. My question is:

I have a model of triangles: I Draw it.

I have a model of triangles, that goes through a geometry shader that spits out the same exact triangles as is from step 1.

Is this much/any slower than simply drawing the model? Is there a big overhead? I simply want to add a check before a triangle gets transformed, so that certain triangles never hit the vertex shader. But I don't know if it is too much overhead even to have the most basic geometry shader, that takes in a triangle and simply spits out the same one.

Is that even possible to discard triangles in a geometry shader?

**Edited by dpadam450, 05 March 2014 - 03:40 PM.**