Ashley - I understand what you are saying and after doing C3 addons for a few years, I hope I have somewhat a feel for how you handle suggestions. In the past I have seen you comment on suggestions, so I was just looking for similar feedback and was not worried if you were not able to.
I did not imply how hard or simple the change is, I understand there is complexity.
In terms of making a full 3D engine in C3, I understand that is not your direction. Instead some 3D features are being added and it is great that the addon SDK is being expanded to support other 3rd party devs so they have the possibility to go in the direction of adding more 3D features, which a smaller subset of the C3 community is interested in. This seems appropriate in terms of the philosophy of 3rd party addons for adding features to C3 that are not directly included in C3 or on the internal C3 roadmap. I really appreciate this and the support the SDK already provides.
In terms of this specific suggestion, I am following your lead here, I am grateful for the addition of the direct-3d rendering SDK support for effects and this suggestion is aligned with that in terms of supporting direct-3d effects in an expanded way that allows for some cool world position based effects. I know it may or may not happen, but I hope you keep it in mind as you update the c3 render engine in the future.
[As an aside the talk of direct-3d takes me back to the 90s and MS doing a new API too...]