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Contour shader feedback.

Unread postPosted: Thu Jan 11, 2018 11:08 pm
by paq
Hello IsoTeam,


Thanks a lot for the new contour rendering option, very well done and easy to use !
Just a little feedback for using contour to render wireframe from Nurbs data.

One of the way to recreate nurbs edge contour is to split the model into individual patch island.
MoI3D (the best CAD mesher around) has an option for that : unchecked "weld vertices along edges"

But so far, to trace this patches border, I can only deal with Clarisse "use shading group" in the pixel filter, and
thus I had to create a unique shading group name per connected poly island.

Quite easy to create this data in Houdini, the flipside is that my test engine here has something like +10000 shading groups :P

While it works ok in Clarisse (quite amazing in fact), it can slow down rendering with some feature, like when the mesh is inside a fog volume.

So it would be great to either :

- Have an option to create contour around connected geometry island.
- Driving the contour based on a custom primitive name attribute created in Houdini. (to avoid having to create thousands of shading group).

(ID per connectivity could be something useful in the utility node, even if it's a primitive attribute you easily create in Houdini)

Beside do you guys have any hint to render backface contour (hidden lines). I tried to invert normals from my model, but as Clarisse render everything on double side, it doesn't help :S

Re: Contour shader feedback.

Unread postPosted: Fri Jan 12, 2018 9:34 am
by sam

Connectivity is something specific to polygons which Clarisse has no knowledge of during rendering. Clarisse completely abstracts geometries to work with a soup of primitives (that can be anything as long it can be defined by a uvw) and point clouds (vertices, particles, control points... you name it.

All that to explain you that it's not really possible to get the connectivity info in the outline shader nor in the utility node.


Re: Contour shader feedback.

Unread postPosted: Fri Jan 12, 2018 4:13 pm
by paq
Hi Sam,

Thanks for taking the time to explain this soup poly concept.

Do you think having an option to pick a custom attribute (like with the extract node) to drive contour rendering is something possible ?
I don't think many customers want to use Clarisse to render CAD wireframe (I would certainly do :)), but maybe it's a feature that might be useful for other usage.

.lwo is supposed to support this part tag id. It's a feature added when Modo was used as renderengine for solidworks (photo360).
I'm not really sure what are the specification for this attribute inside the .lwo file. All I know is that MoI3D has a option to generate this tag.

Otherwise the .abc route is just fine. generating an attribute name by connectivity is about to add one node in Houdini.


Re: Contour shader feedback.

Unread postPosted: Fri Jan 19, 2018 2:58 pm
by sam
Hi Paq,

It would be really tricky I think. Originally I was thinking that you could texture the line width with an extract property to mask line size but unfortunately it won't work. What you would like if I understand well is to use a property to make edges appear in the very same way we do currently on shading groups right?

Re: Contour shader feedback.

Unread postPosted: Mon Jan 22, 2018 4:23 pm
by paq
Hi Sam,

Exactly, so having the same result as with shading group, but based on a custom primitive attribute name (or integer).
In a hope that it will give better performance than dealing with thousands of shading groups (like with my actual workaround).

But I don't want to waste your developing resource for a such specific request, you guys have probably other bigger fish to fry ;)

Re: Contour shader feedback.

Unread postPosted: Mon May 21, 2018 2:33 pm
by dboude

I added an entry for this request (#ID8350) ;)

Cheers !

Re: Contour shader feedback.

Unread postPosted: Mon May 21, 2018 4:41 pm
by paq
Great, thanks Démian.