Inaccuracies with offseted Shape Extrusions

[MichaelMenzi]

Hey Guys,

thank you for the awesome tool first of all. I use it often since a few years, but for minor spline related stuff most of the time.
I'm now digging into the possibilities of the generator tools, again. I checked it out before, but just for my own pleasure. 
Now I'm asked by my employer (we build virtual/mixed reality, motion enabled simulators) to build a rollercoaster scene in unity to demonstrate a usecase with our hardware and unity as an IG/whole engine. 

Ok, curvy is my first goto tool for things like that, but I ran into some problems.

My main goal is to have ONE curvy spline defining the TRACK of the COASTER.
I'd like to design the editor tools needed to generate a track scene out of it.

The situation:
I hooked up some generator graph with one MAINSPLINE, a RAILSHAPE and then some ModifierTRSShapes to place the rails offseted where they need to be, BuildShapeExtrusion and BuildVolumeMesh nodes and then a CreateMeshNode.

This actually works fine, but I have some visual artefacts I can not resolve.

The problem:

There appear edges in the (offseted) shape extrusions and especially afer a swirl it doesn't fade back well. Really not well.

Resolution parameters are (as far I can see) on max settings (in the forward axis).

Curve formula I'm using is Bezier, but i tried others and the results were the same (or otherwise not what i wanted )




Do you have any suggestions how I can get better results from the rasterizing/meshing modules?

I'd really liko to do this with curvy

Kind regards

Michael Menzi
(Brunner Elektronik AG)

[_Aka_]

Hi
Is the Optimize parameter set to true in your shape extrusion module?
If yes, try reducing the value of Angle Threhold, or disable Optimize.
If not, can you please send me a scene with the issue?
Thanks

[MichaelMenzi]

Hi,
thanks for your answer. Yes, I tried it all
I narrowed the problem down and understand it a bit better now.
I think it's the hard change in normals on the spline when doing a swirl.
With a generated mesh on the main spline this isn't a problem, but as soon the generator shape gets offseted, either with "TRS Shape" or with "Path Relative Transform", then there is a sudden change in direction on the offseted mesh on start and end of a swirl, because it relies on the normals of the spline.

Completely makes sense to me, so this thread may morph into a feature request beg, rather than an actual problem with curvy

I think it would be an awesome feature:
A new parameter that fades in/out the swirl at the start and end of the swirl segment/anchor group.
A distance percentage value for instance.
With this, we could do swirls over an anchor group and say "fade in from the first CP over the first 10% of distance" and "fade out to the orientation of the last CP over the last 20% of distance".
Additionally this would decrease the tuning demands for swirl turn parameter and increase the flexibility overall

Let me know what you think about the idea, or if you see a possible solution to achieve this with the already existent system.

regards
Michael

[_Aka_]

Hi
I am thinking of a solution that I will test implementing in the near future. The idea is to have a Variable Mix Paths module. Before continuing reading, please make sure to understand what the Mix Shapes and Variable Mix Shapes do to know what I mean by Variable Mix Paths.
Once that module implemented, you could use it to mix between a swirled path, and a non swirled one, so you can fine tune at what sections of the path the swirl should appear and disappear.
Is my answer clear?

[_Aka_]

Also, maybe even better, instead of using swirl, just set a Control Point as an Orientation Anchor, and rotate it. The normals will be continuous that way.

[MichaelMenzi]

Hi,
Yes, that sounds promising. Not just for my current use case. I remember wishing to have a Variable Mix Paths module before for another project!

I actually gave it a shot today and tried to implement the swirl lerp myself. It was quite a good experience adding own props to CurvySegments and handle them, because your code is very clear and well structured, so props for that.
But the task itself is not that trivial and my resources are very limited, so I abandoned the approach...

Having tons of Control Points in the scene is something I try to avoid... It will make level design a tedious task...

But anyway, the issue is not a dealbreaker and I can work around it. But I will be a happy tester of the Variable Mix Paths module!

So long, cheers!

[_Aka_]

It was quite a good experience adding own props to CurvySegments and handle them, because your code is very clear and well structured, so props for that.

Glad to read that

Will keep you updated once Variable Mix Paths is available