Blend two crv ends on a srf

Rhino Rhino for Windows
1

Hello,

I was wondering if it’s possible to blend two crv ends (red lines) on a srf (curvature blend) and at same time the blend should touch a point on the srf. (start of blue line)

Thanks!

blendcrvonsrf.jpg1047×944 150 KB

blendcrvonsrf.3dm (8.3 MB)

2

I’d probably use _BlendCrv and align it to where I think it should be and use _Pull to bring it back to the surface…

Andy

3

Thanks Andy, I’ve tried using pull, but you can’t pull it into place so it touches the blue line plus once pulled there are many points created so hard to manipulate.

4

I agree with Andy on the use of BlendCrv. I’d add that Pull can use History too. Follow that with the EndBulge command used to adjust the blend and subsequently the pulled result. Here’s an example…
blendcrvonsrf_BrianJ.3dm (8.3 MB)

Alternatively, you could use InterpCrvOnSrf between three End Osnaps. Then use Match to adjust continuity and Pull to make sure it’s on the surface again. The transition area in Match is more abrupt though and I prefer the first method in this case myself.

5

Hi Philippe - try:

BlendCrv from one of the reds to the edge of the surface - G2 at the red curve. and G1 at the edge. Before acceping the blend, drag the end on the edge up to snap to the End of the blue line. Repeat the other way. Pull will then make a smaller change. but note your surface is not quite perfectly curvature continuous at the location of the red curve’s end.

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Repeat for the other half but you can blend to the first blend directly.

blendcrvonsrf_PG.3dm (38.9 KB)

-Pascal

6

The other way is to _UnrollSrf with the curves. Use the _BlendCrv to get it something like. Draw a circle using 3x tangents to get the bulb/nose of the shape and then redraw a circle using that approximate radius. Use the same 3x tangent circle command to draw a circle which then touches the original curves and the outside of your new circle.

Use the command _CreateUVCrv (Google some tutorials) and then use _FlowAlongSrf to put the curves back in place.

Just so you know - I mirrored the top curve as the bottom one was not symmetrical

Andy

blendcrvonsrf-1.3dm (8.3 MB)

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7

YAY thanks guys, lot’s of useful info!! Appreciate it!