Paul Hatton takes a look at creating cutaway renders using the new V-Ray clipper in part 6 of his look at the features of V-Ray 3.0...
This tool is absolutely brilliant! Gone are the days of having to fudge cutaways or use substandard tools or workarounds to create those gorgeous cutaway visuals. These types of visuals/videos are more common within the engineering sector as people are keener to communicate the internal workings of pieces of kit. It does however have its place within the architectural market if you want to create a 3D floor plan for example and cut the roof off. We'll delve into how to use this tool in a production workflow and then you can imagine all the amazing possibilities it opens up to you.
What is it?
Simply put it's just a geometry primitive which lets you cut away parts of your scene. It's important to note that this is only a render-time effect and therefore you won't get any feedback in the viewport. This does have a benefit though as it means your actual geometry in no way gets affected and messed up. It can be distinguished therefore from cutting the geometry or using a Boolean operation, thankfully.
This brilliant render time effect will keep you happy as you render cutaway after cutaway
A major limitation
Maybe I'm fussy but I would love to have seen this tool extended to be any shape whatsoever rather than just a plane. I'm sure they'll adapt it in future iterations of the renderer and I look forward to that. Having it as a plane is useful but there are occasions when I want a more complex cutaway and I end up having to create several clipping planes to do the job that one single piece of geometry could have done for me. Like I said, maybe I'm being fussy!
Multiple planes can be stacked to achieve a more bespoke cut. Ideally this would be achieved with one cutting object but this isn't possible yet unfortunately
I love the V-Ray help files because they are super helpful at detailing the limitations of tools rather than hiding things. I really appreciate this honesty. Couple of points then. Firstly, if you have overlapping triangles then the V-RayClipper may product undesirable artifacts. Use the xView 3ds Max tool to track these down. Secondly, the Clipper works best with closed objects. This warning can be ignored it you've got all your back faces defined correctly.
Overlapping triangles should be avoided at all costs anyway, especially when using GI, but they should also be avoided with the V-Ray Clipper
Creating the plane
Fire 3ds Max up and head over to the ‘Create' panel. Use the drop-down to select ‘V-Ray' and finally select ‘V-RayClipper'. To add it to the scene simply click once in the viewport. It has no size properties so expect it to act more like a V-RayPlane rather than a standard plane. This also means that it is an infinity plane. Keep that in mind when you're fine tuning what it cuts through.
It's just a standard geometric primitive so find it with the usual suspects over in the V-Ray part of the create panel