Hi Klingbeil,

> i tried joining everything and then showing the points but nothing happens.

Just to clarify - this is normal behavior, if you look at what points you were actually getting before you did the join you should be able to see that the points for each little hex are actually 4 points of a simple quad plane surface that is somewhat larger than the hex itself.

So 2 neighboring hexes that share a trim edge don't actually share surface control points in common - that's why when you join them it won't let you turn them on because if you pulled one of them it would yank the surfaces apart at what was supposed to be a joined shared edge.

You can show points on totally separate surfaces that are not joined to one another, or in some other special cases like on a box where all the surfaces that are joined actually have control points in common in their underlying surfaces.

- Michael

i'm trying to do this http://moi3d.com/forum/index.php?webtag=MOI&msg=817.4 with a hex instead of a square

Just to illustrate further with your particular file - take these 2 adjacent hexes for example:



If you turn on control points for that selected hex, you'll see that the points are actually 4 corner points somewhat larger than the hex itself like this:



That hex is a trimmed surface - the "underlying surface" is a simple 4 corner plane and the hex edges are trim edges that are marking the outer boundary of what to trim away from the outside of the plane to make the final shape.

When you manipulate those control points, you are manipulating the shape of the "underlying surface" plane, like for example dragging the corner point will do this:



Notice there that after dragging that point there is a gap opened up between the hex pieces - that's why points do not show when you have joined pieces like this together, because dragging on them would normally open up holes between what was supposed to be a shared common edge.

If you turn on control points for the other surface, you can see that the control points of the 2 surfaces are not really aligned or touching with one another in any way - it's the trim edges that actually touch each other:



Hope this helps explain it!

- Michael

Hi Klingbeil,

> i'm trying to do this
> http://moi3d.com/forum/index.php?webtag=MOI&msg=817.4
> with a hex instead of a square

NURBS surfaces are fundamentally quad-like in structure. Whenever you have a surface that looks like it has more than 4 edges on it, those are actually trim curves cutting away some base quad-like surface.

It's not quite the same as a polygon quad because the "NURBS quad" is like a sheet of rubber and can be all bendy and have a lot of points in it instead of just 4 corner points, but every underlying surface is made up of a row and column quad-like grid of control points.

You can have edges of the surface squished together into a point, that's how for example spheres are made - those are quad-like surfaces that have their top and bottom edges all compressed down to a pole point.

To get something like that link but with a hex shape would involve making a similar kind of "pole" point as a sphere, with the pole at the center of the hex. You can use Rail revolve to make a shape like that, draw a line from the center of the hex to one edge, then select the line as the profile, run rail revolve, pick the quad as the path, and give a revolve axis vertical to the hex plane, and that should build a revolved hex surface with a squished together edge at its center. It will actually be split up into 6 different surfaces since there is a creased boundary around the outside and surfaces are split into multiple pieces at any sharp edges like that. Also you'll need to turn off the "Cap ends" option in Rail revolve so that it doesn't put a second plane surface joined on to it - it thinks there is a planar opening at the bottom since all the open edges are on the same plane.

I've attached a hex created in this manner - if you turn on control points for it you'll see that it actually has points at all juncture points instead of being trimmed.

You can build a repeated structure out of this tile and join them together and still get control points to turn on (until you do some boolean or trim or something that introduces trim edges instead of natural surface edges), but these are actually little separate triangle facet pieces and won't be a single big smooth surface when you distort their points unlike that example in that link.

- Michael

aaaaah ok i see now. sorry, i'm still in a Sketchup mindset. that's why i tried making everything with lines first, to intersect the surface and have each point of the hex be control points for raising and lowering. that's the way Sketchup's sandbox works. it's clunky, but it gets the job done. however it does create objects with facets (which shows in the CNC'ed parts) and OMG does it take a lot of processing power when there are a lot of points.