Im new to Grasshopper. Im trying to setup a system, that can control the shape of a closed nurbs curve , by changing the weight of half the control points - or rather: every second control point - with a single slider.
Step 1: The system should be based on a number of “corner” points, that I draw manually in Rhino.
NOTE: These points are NOT in a plane, they will be very arbitrary from each other.
next steps should be defined in Grasshopper, and the aim is a system, where I can a) move the cornerpoints manually in Rhino and b) change the “corner” ctrl-pt weight with a single slider in Grasshopper.
I hope the attached image can explain what I am trying to do…
Step 2: These points represent the corners in a polygon.
step 3: How to set the midpoint of each side in the polygon ?
step 4: How to define a Closed Nurbs curve from the corner points AND the midpoints?
step 5: How to select ONLY the “corner” control-points and change their weight with a slider ( range 0.4 - 10) ?
You can see in the attached image, and the attached Rhino file, that “corner” control points value of 10 creates a “near-polygon” with very sharp corners
Step 6: - and a value of 0.4 creates a very smooth transition in the “corner” curvature
If you are curious what I am up to, please see the attached test3-pullsrfGH, where I am pulling a polygon onto a surface in Grasshopper. My problem is, that I actually want only the adjustable Nurbs curve on the surface.
The ultimate aim, is to be able to take any surface, and by use of adjustable points - and the control point weight slider, I can project a cellular grid onto the surface, and adjust the “sharpness” of the corners in the grid.
Its a bit like Voronoi, only that I control the design manually by nudging the corner points, not the centerpoints.
If you know of other Voronoi techniques like this, please share with me !
Thankyou very much ! This has very high priority for me !
CTRL POINT WEIGHT.3dm (3.1 MB)
Test3-pullsrfGH.3dm (3.1 MB)
Test3-pullsrf.gh (12.6 KB)