[vtkusers] OpenGl help

[Jianlong Zhou]

Hi vtk users,

I have a maybe stupid probelm but I am not able to solve it.
The question is:
I have two objects in 3D space, let's say two polygons. These two polygons are 
overlapping. Let's say the first polygon is red and the other is green.
The wished result is to have the overlapping region in brown (that means 
red+green). How can I do this?

I'm able to draw these two polygons at their locations that's no problem - but 
all I want is to automatically add the color values if they are at the same 
location!

Thanks!

Andreas