I have tried a number of combinations of nodes, looking for a method to tell the displacement vector to not be the normal, but be something else.  The docs hint that this is possible, but I have yet to find any discussion or exmaple of “how to do it.”

I believe that I should be able to output the vector from a projection node and substitute those vectors for normals on the displaced surface, but exactly “how” eludes me.  First of all, I do not see an “outVector” as an option from the projection node. 

2nd, the default displacement node does not have vector as a possible input.

In the ShadingGroup, I can use “any scalar” to influence displacement in Mental Ray, but that displacement is always ALONG THE NORMAL.

How can I switch the displacement direction from Surface Normal to CoordinateSystem("camera NDC” OR “camera frustrum")?

Thanks.
- Jimbo

There is possibly another way to solve my issue and allow the process to continuing using displace along the normal. 

If I can recompute all the normals in the scene to point to the camera XYZ location.  Since normals are simply a surface vector (0,1,0) with a length of 1 unit, how can I gain access to the normal (eg. surface_vector(x,y,z))?  If I can connect these values to the camera_location(x,y,z), then I can simply continuing displacing along the normal with the existing displacement shaders provided.

If not, then my best solution is to use RenderMan.

- J

Eh, hello?  Bueller?  Anyone?