[Plugin] BezierSpline - v2.2a - 22 Apr 21

jeff hammond · 22 Jun 2011, 04:32

NEW FEATURE SUGGESTION: "MEAN CURVE"
Does anyone else think this is a good idea?

Cheers,

Joel

hey Joel
i'm not quite convinced that your manual method is actually giving a mean curve.. i assume you're just connecting vertices then drawing segments through the midpoints.. i guess it sort of looks ok in the example you posted but it's not going to always work out that way.. see these two curves (well, one curve that's been copy/flipped)..

mean.skp

try your manual method on those and you'll soon run into problems.
while it might be possible to make a plugin that can do an actual mean curve (or something close to it) in sketchup, i think it's going to be much more difficult then simply playing connect the dots.

ivreich · 24 Jun 2011, 13:51

Hi Jeff

Thanks for replying. You're right; the manual method is simply "connecting the dots" as you say. It was the most logical way of illustrating my point. I think I see your point though; the manual method presumes a more regular spacing/matching of vertices between the two curves.

I suppose complex pairs of curves would have to be "rebuilt" (pardon the Rhino lingo; I've just finished working at a firm where Rhino is pretty much a religion: if it isn't built in Rhino it isn't worth looking at) to match each other's vertices before the manual method can be used.

I don't know the math behind creating mean curves, it was just an idea that popped into my head one day at work. Any other suggestions?

Cheers,

Joel

jeff hammond · 25 Jun 2011, 07:14

@ivreich said:

I suppose complex pairs of curves would have to be "rebuilt"

this is where sketchup really starts to breakdown as far as trying to make it nurbs like..
you can, in essence, rebuild a curve using this plugin.. if you right click on one of the curves in the mean.skp then go BZ- Convert To --> Polyline Divider (or polyline segmentor) then you'll be able to set the curve's vertices to an equal spacing (or to an evenly divided # of segments)..

the problem is, you end up with too many vertices in the looser parts of the curve Or too few in the tighter areas. (at least in the example sketchup.. these commands come in very handy for many situations)..

re: mean curve in rhino.. personally, i don't use it or have a use for it (that i know of )but one thing that sort of surprises me is that illustrator actually has a mean curve command that is seemingly superior to rhino's.. with illustrator, you can choose the amount of divisions (ie- 2 new mean curves in between the original ones).. you can do it with rhino by repeating the command as long as you want an odd amount of average curves but even then, it takes a lot longer than doing it once..

but hey, i guess i'm going way off topic here

fredo6 · 25 Jun 2011, 13:19

It's relatively easy to do it.
Actually, I have this type of function embedded in Curviloft
The only remaining part would be to build a decent GUI for selecting the curves.

Fredo

jeff hammond · 25 Jun 2011, 15:15

oh yeah. i guess with curviloft you can do exactly this as long as the curves are in 3D space (i can't get it to work if both curves are flat and on the same plane)

TIG · 25 Jun 2011, 15:55

EEbyRails will make the average-curve between the two rails if the Profiles are a straight-line curve made from two equal length edges [use divide on a line drawn between the curves ends and weld as a curve]. This works in full 3d AND in 2d even if the curves are flat and even coplanar... Just erase the mesh's ribs and use the 'spine' edges to weld into an averaged-curve... Obviously the average is 1/2 but if you wanted to weight the result - let's say a 3rd then divided the profile line in three, erase the ribs and the two mid- spines are at 1/3 from their nearest 'rail'...

jeff hammond · 25 Jun 2011, 16:13

the thing with curviloft is that you can choose to generate only the edges if you wish so there's no deleting surfaces afterwards etc..

TIG · 25 Jun 2011, 16:21

Jeff... doh! moment for me...
Use EEbyLattice and chose 'Rail' only option to get a central spine curve [auto-welded and grouped] without the needed to mess on erasing ribs made from EEbyRails

jeff hammond · 25 Jun 2011, 16:27

@tig said:

Jeff... doh! moment for me...
Use EEbyLattice and chose 'Rail' only option to get a central spine curve [auto-welded and grouped] without the needed to mess on erasing ribs made from EEbyRails [attachment=0:1z22r8l6]Capture.PNG[/attachment:1z22r8l6]

lol!
i had forgotten about that option as well

fredo6 · 25 Jun 2011, 21:20

@unknownuser said:

(i can't get it to work if both curves are flat and on the same plane)

Jeff,

Do you have a particular model where it does not work. In general, that should give the results.

By the way, you can choose the number of internediate curve via the #seg parameter (but not the spacing).

Fredo

jeff hammond · 25 Jun 2011, 22:38

hi Fredo,

it's a lot faster for me to just explain it in a video.. i hope it makes sense

[flash=700,428:2w2q5yyr]http://www.youtube.com/v/bl7TMkBWpZc?version=3&hl=en_US&rel=0[/flash:2w2q5yyr]

fredo6 · 25 Jun 2011, 23:21

Jeff,

Well spotted!

Options for generating geometry is one feature of Curviloft which is not terminated. I may however add the option to keep either / or the mesh lines in a next release quickly
in Skinning, I purposedly removed the meshing of surfaces that are planar, precisely to avoid too many polys and faces. Unfortunately, I did not provision an option to inhibit this feature.

Thanks again. I'll try to incorporate all this in a next release

Just one remark: with your skinning approach, you don't need to divide the segment. Curviloft can do it for you via the Sampling parameter.

Fredo

jeff hammond · 25 Jun 2011, 23:57

@unknownuser said:

Just one remark: with your skinning approach, you don't need to divide the segment. Curviloft can do it for you via the Sampling parameter.

Fredo

ha.. yeah, i knew that (as it's a great feature of curviloft in general). what i meant to do was use the manual divide as a way to show me trying to force curviloft to make the lines to no avail.
for whatever reason, i ended up doing it in a few different parts..
i should maybe try following a script next time i make a video

redsteel · 1 Jul 2011, 21:45

Hi Fredo

I just want to say thank you very much!

vidy · 27 Jul 2011, 10:45

Dear Fredo,

First of all i want to thank you for this magnificent plugin..
but i have question, is there a way to slow down the movement of the grip, when we select a grip or a point to edit it?? i usually have this problem when i want to move it on certain axes (after im press ctrl button)

Regards,

clifdon · 3 Aug 2011, 22:12

Great thank you for this plugin .

helmholtz · 28 Aug 2011, 02:19

Thank you greatly good sir

marcel.forum · 28 Sept 2011, 17:19

Dear Fredo
Big thanks for this plugin.

--
Marcel

xrok1 · 5 Oct 2011, 22:06

spotted this in another thread. Worth noting:

rv1974 · 25 Oct 2011, 07:47

Hi Fredo,
I recently updated your spline tools set and unfortunately it stopped functioning.
I get the toolbar, I can activate the commands, but they simply don't draw.
I'm pretty sure the file's structure is OK, the FredoLib is updated.
What could be the reason?
Thank you in advance.
BTW where could I download the older version?