Cut circle with a sphere

General TouchDesigner Discussion
1

Hey !
I’d like to cut a circle with a sphere to havce an arc of a special shape.
Tried bool, surfsect and curvesect, which one is the best approach?

Thanks,
S.

2

hello,

I imagine you need it to be in the 3D world (SOP) ?
do you need a closed arc (disc) or open arc (just the contour) ?

3

Yes I need a SOP, and an open arc !
Thanks

4

Have you tried the open arc setting in the circle sop parameter page ?

circle_arc
circle_arc1280×644 34.7 KB

5

Hey,
I need to cut the circle according to the moving position of a sphere, so it wont work.
Thanks

6

Hm, can’t come up with a better solution right now and this one is a bit crazy - but maybe it’s what you want?
Basically I’m using the Delete SOP to delete points of the circle that are enclosed by the sphere. Now to make a arc out of it, the points need to be reordered so that the first point is always at the position of the cut… And that is the slight weird network with slopes checking where the largest difference in value is as either x or y must make a bigger than usual jump when there is a cut…

I’m using experimental for this…

Cheers
Markus
cutArc.tox (1.8 KB)

7

ok, this is nicer! I’m saving the point index into a custom attribute before cutting the circle. Now I know which point is the first one to be cut and that is what I need to shift the 0 to.

  • slight edit, now also takes care of circle if sphere is not cutting anything… Using a circle that is set to open arc as a source geometry.

Cheers
Markus
cutArc.v2.tox (1.6 KB)

8

Hey Markus,
Had no idea it would be that complicated, but it works just fine !
Thank you !
S.