Trim curves in Grasshopper?

Question.. i want to cut holes in some complex curves? is there a simple way to trim or split or itnersect curves with other curves or curves with lines? i dont find a solution so far.. or do i need to work with bezier and the normals/tangents?

thx

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screensh1.jpg, 532 KB

Replies to This Discussion

Permalink Reply by Matt Gaydon on July 15, 2013 at 12:10pm

Have a look at Crv/Crv Intersect followed by Shatter component then use a Cull Pattern Component to remove all the parts you don't want. You may want to explode/ remove the lower edge of the rectanges before runing the intersect command to get out cleaner data.

Permalink Reply by Phil on July 15, 2013 at 12:20pm

ok thx!

its no rectangles. it's 3 lines made with a curve point (curve eval) so it should be perfectly on the curve. i will test the method. have not found the shatter thing before (hard to figure out that name without knowing).

Permalink Reply by Phil on July 16, 2013 at 2:47am

hey matt!
i dont have a crv/crv intersect! there is a line/line intersect (karamba) but no curve one.. and the line isnt accepting curves. hmm.. is it a plugin?

Permalink Reply by Sylvain Usai on July 16, 2013 at 3:16am

It's inside the "physical" panel, not the "mathematical" one in "intersect".

Try typing CCX in your canvas

Permalink Reply by Phil on July 16, 2013 at 3:24am

ah you're right!
thats a bit weird.. even when i type "curve curve" or "curve itnersect" i couldnt find.. ;)

cool. seems to work for me!

Permalink Reply by Phil on July 16, 2013 at 3:42am

the Trim is solved.. but theres another problem! The "Cuts" or "Gaps" has to have a precise size so the model will work properly afterward. i used EVAL CURVE to get the points. but when i do both points like this the distance between the points (= the siz of the Cuts) is precise in direction of the curve tangent.. whan i need - cause of the vertical joints - is a horizontal measurement like in the drawing.. is there a easy way to achieve this?

what i plan to do is the have a flatten/ projected to cplane version of the curve and measure there.. but perhaps its an easier way without that much unnecessary geometry in the background.

thx

Attachments:

screen2.jpg, 126 KB

Permalink Reply by Sylvain Usai on July 16, 2013 at 4:24am

Not sure to understand; the first situation is the one you have, the second one is the one you want?

If you are sure about your reference plane, maybe you could use an horizontal frame on your curves, move it with the same distance you used for the circle radius and then create a normal plane (vertical) which you'll use to intersect the curves (Plane|Curve)...

Permalink Reply by Phil on July 16, 2013 at 4:43am

exactly.. eval curve always works with the curve so the dimension is precise for the tangent. i want to have precise size of the gaps on world plane (horizontal) like the drawing on the right.

but the problem with your idea is that i want a script which works for all the input surfaces. that means i cannot shift the plane "manually" in a direction i have to do it in relation to the curve direction.

Permalink Reply by Sylvain Usai on July 17, 2013 at 2:30am

You won't have to shift plane manually... Not sure to understand, tell me if this is helpfull (enclosed definition)

Sylvain

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SplitSus.gh, 17 KB

Permalink Reply by Sylvain Usai on July 17, 2013 at 2:44am

Some parameter on curve were too close from each other ((t+1)-t < HoleSize); you probably won't need it as you will not use random... fixed it anyway :)

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SplitSus.gh, 19 KB

Permalink Reply by Phil on July 17, 2013 at 4:15am

yes you were right!
i adapted your definition to my needs (curiosity) and it works.. but in the meantime i realized that its even better (more performant cause less geometry) to do a bit more math before the actual slicing of the surface.

so the right approach (i hope it will work till the end but it looks good so far) is to reparametrize the surface in the beginning and do all the slicing with calculated uv params and then MCX > sorting > etc.

Attachments:

curve_trim_sorting.jpg, 364 KB

Permalink Reply by Phil on July 17, 2013 at 6:43am

ok, so far so good!
thx again for support

the first part of the script works well and quite smooth on my old HP laptop.
it's one script which directly translates a double curved surface into beams with the necessary "gaps" to put them together. i can control the amount of U and V cells and the height of the structure and the size of the "gaps" (to adapt to different material)

next step will be a more complex program for the height. i want to make the structure become more thick where the curvature of the base surface is higher. always iterested in input off course :)

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