Dear All, I'm trying to port the multilayer peeling shader from HLSL to Cg. Really, it ought not to require much in the way of change, but I'm getting a compile error for the statement float fp32color=pack_4ubyte(color);. The compiler claims Error c1115: unable to find comptaible overloaded function. Now color is a float4, and fp32color is obviously a float. I'm looking at the nVidia user manual write now, and it clearly states that pack_4ubyte takes a float4 and returns a float, so I'm at a lose to see whats going wrong here. Anyone understand this? Regards, Jesse