I'm working (yet again) on some grass and still trying to get something that really works well for me in hi-res for details and mid-distance. I am working on this with LukX and we are both struggling a bit.
I am using the nested FPP object technique, so I have single grass blades distributed over a 15cm circle. Each has material ID's assigned so that all poly's on a single blade have one ID, and I have randomly assigned 1-10 as the MatID for each blade. I have a material using Forest Colour and 10 maps to randomize the diffuse colour as well as spec and bump. It works great on the single patch of grass. However, when I use that FPP objects as the geometry for another FPP to scatter over a wide area, then the Forest Colour isn't working properly and the colour cannot be assigned to individual blades properly - it's creating big patches of colour.
Does nesting FPP objects break the Forest Colour mapping somehow?