I need to match a surface boundary G2 to the large untrimmed surface by projecting the boundary normal to the surface or using the Y-axis. Then, I want to trim the large surface with that boundary. In “the other software” there’s a tool for that, but what’s the “Rhino way”?
Also, I noticed that one cannot use BlendSrf between trimmed edges, that DupEdge on a trimmed surface only outputs all four surface boundaries, that RefitTrim does not work on a surface trimmed on opposing sides, and that MatchSrf has no numerical control and CV-blending options and other options.
I was able to trim the large surface by using split with “crv” trick. This trick is done by typing “crv” in the command before picking the cutting objects.
I think match surface with the on surface option should be the right thing to do here, but I didn’t have any luck with that.
Thanks, the “On Surface” option seems to have worked, but there’s no feedback as to if the surface normal or Y-axis was used, one cannot make a selection. Also the previously achieved G2 continuity on the other edges is now lost
Your “crv trick” to pick surface edges for trimming should be in the Rhino online manual, but it is not
Do you know why I cannot use trimmed edges for BlendSrf, or to snap a BlendCrv to, and why DupEdge extracts an edge from all four boundaries of a trimmed surface, instead of the one I click on? In Alias or Catia, for example, any isoparametric curve (surface boundary or inner one) also “behaves” like a “regular curve”, and can be used for anything.
Rhino align projectV7.3dm (556.9 KB)
Hi Lagom, I am sure you have things you are trying to figure out . I did this wondering if it is close to what you want.? I projected some duplicated edges then did some curve matching as well as 2 sweep rail. —Mark
No, I have no idea why BlendSrf is not working on trimmed edges. I’m not understanding your question about BlendCrv, or maybe you need to sub-select the edges when using BlendCrv.
You can always just sub-select the edge you want and copy-paste. If you need isocurves use the extractIsocurve command, or maybe use split with isocurve option.
@markintheozarks Thanks, well, unfortunately, both G1 and G2 continuity are worse then in my degree 7/5 attempt, and the surface has very many spans, please see below.
@jari.huuskola Cheers, thanks, let me try to explain better with a screenshot. Trying to figure out the proper “Rhino way” to build easily CV-modifiable “G2 matchable” single span surfaces.
Not sure what is the proper way, but I would just get rid of the trimmed edges completely. Just split those surfaces with isocurve option and you will end up with clean and BlendSrf friendly surface edges. Complex trimmed edges are dead ends.
For example, you can model this entire corner thing easily with single span surfaces, only the large surface should be a trimmed surface.
I rarely use DupEdge and fail to understand why would you use it here.
@jari.huuskola I wanted to duplicate some edges to have curves to then use the BlendCrv command, which does not work on the edges of trimmed edges. With other software, every surface boundary is also a curve that can be used for all kinds of purposes, so no extraction, duplication, etc. is necessary.
Regarding the splitting of trimmed surfaces with isoparametric curves - how does that help me here with surfaces that are the result of multiple prior trimming operations? Please see the screenshot below; the isoparametric curves go into an entirely different direction compared to the adjacent trimmed edges, and the highlight flow of the surface in between would be off.
Maybe this screenshot helps; this is how it would be done in other software; single-click convert trimmed surfaces into untrimmed surfaces, use their now natural edges to build secondary or tertiary G2 continuous surfaces without much ado.
The root cause of these problems is the separate edges of each surface have become a single edge. I don’t recall ever seeing that before, and don’t know what could have caused it.
Repair method 1
DupBorder the border of the surface.
Explode the border curve.
Untrim the surface.
Trim the surface using the exploded border curve.
RebuildEdges
Repair method 2
Use SplitEdge to split the surface edge at each corner.
RebuildEdges
Repair the trimmed surface edges and “every surface boundary is also a curve that can be used for all kinds of purposes, so no extraction, duplication, etc. is necessary”.
@Lagom in your screenshot B and D surfaces have clean untrimmed edges, I would try to make similar edges to A and C surfaces and then use blendSrf etc. This is what I was after. Unfortunately, this will require quite lot of manual work in Rhino.
Also take a note what @davidcockey wrote, there is something strange going on with A and C surface edges. I didn’t notice this!! So, If you split the surface edges by the corners, the blendSrf will at least work as it should, even with the trimmed edges.
All right, thanks, that’s what I feared. And, yes, B, D and E are G2 fillets, where only one side was trimmed by the curves, and thus RefitTrim did work on these.
