We need Spike and RemoveSpike commands

Crease and RemoveCrease commands control edge made by a row of control points. It would be nice to have similar commands for single control point. These commands would make spike and remove it. Without such commands the only way to make (imperfect) spike is adding lots of control points.

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What is a “spike”?

A cone having small apex angle.

Like a creased edge, but with a vertex.

Why not just have crease and uncrease work on points as well as edges? No need for an extra command.

Thanks for the request… field as https://mcneel.myjetbrains.com/youtrack/issue/RH-54305

Crease and RemoveCrease already work on vert selections but the attached edge is also creased or not at the moment.

That’s the same way it works in Clayoo, too, I think. I’m curious as to what it would look like to only “crease” a vertex. I’m away from my workstation, but I imagine I could fake it by making an edge with a length equal to 2x document tolerance and creasing it. Workarounds are obviously best avoided if possible, and this particular one would require at least four edges connected to the faux “point”, which might be limiting in some ways. It’ll be interesting to see.

Agreed, but here’s a way to do this specific case now using Revolve as Subd and a Subd friendly curve as well. The adjacent creased edges would be there but very tiny. I know it’s not what is being asked for, just showing it as a possibility.
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We’ll need to wait for @dalelear review on that report to know if vert only crease could work with Rhino subd.

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The Crease and RemoveCrease commands can be used to add and remove spikes by changing vertices from “smooth” to “corner” and vice verse.

image

To experiment, select a vertex and run the Crease or RemoveCrease commands.

Spikes created by creased vertices have all edges turned into sharp edges. You can use RemoveCrease to remove some of the sharp edges, but a “spike” point (corner vertex) needs to have at least two creased edges.

When creased edges are not acceptable, the technique demonstrated above can make an “almost spike”.

– Dale Lear

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You can make a “singular spike” by setting all vertices around a boundary to have the same location (this is the way NURBS cones get their spikes as well). The SetPt command can be used to set the 8 vertices. The faces that appear to be triangles are actually quads with a zero length edge. The Rhino SubD evaluation algorithms are robust enough to render the object and convert it into a decent NURBS object as well.

If this approach is useful, we could make the Crease command have the option of choosing between a “singularity spike” or a “corner vertex” spike.

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A command option to select singularity spikes would be much more intuitive. I can see a number of circumstances where it would be useful.

While we’re asking for more and more features, would the option to set vertex and/or edge weights make any sense in SubD? I could see it as potentially useful to be able to more quickly be able to soften a spike or a crease without having to add subdivisions. Imagine trying to soften or sharpen some studs or spikes on an irregular subD object. Scaling the vertices you want sharpened in and out normal to the surface seems like it would be more of a hassle than just changing their weights. When I use Clayoo I don’t have that option: I have to subdivide and/or carefully move vertices with clunky controls.

I was thinking the same and had filed it as an internal request… https://mcneel.myjetbrains.com/youtrack/issue/RH-47061 for future reference. It’s currently not slated for the initial 7.0 launch. FYI @dalelear

For variably sharp edges I think we’ll need to use SlideEdge and work with the traditional edge to edge distance method. My recollection is that variable crease values don’t translate well between subd apps which could be an issue.

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Traditionally Catmull-Clark subdivision surfaces are not rational (they don’t have weights). It’s possible to consider adding them, but the complexity that is introduced may greatly outweigh any benefits.

Definitely no weights (akin to NURBS control point weights) will be available in Rhino 7 SubD.

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Gotcha. Makes sense.