Randomize the radius of a curve

Question

I have a curve object that includes several curves. I want to randomize the radius of each separate curve piece. Each point on the curve piece should have the same radius, but each piece has a different random radius.

Some control is necessary. I want to be able to set a minimum and maximum number for the radius.

Is there any existing methods or addons to do this? How about with python?

Answer 1

To do it manually, in edit mode use L to select linked points and adjust the radius property which will be applied to all selected points. The radius property can be found in the properties sidebar N.

Or you can automate it with python. A curve object can have multiple splines, each spline then has multiple points. Note that bezier curves and nurbs curves use different property names for the points. For bezier curves it is bezier_points while nurbs curves use points.

import bpy
import random

c_obj = bpy.data.objects['BezierCurve']

for s in c_obj.data.splines:
    spl_rad = random.random()
    # change to s.points for nurbs curves
    for p in s.bezier_points:
        p.radius = spl_rad

Answer 2

If you have a single curve object that includes several curves, changing the Bevel Depth in the Geometry panel will change the radius of all curves in your object...

One way to do what you want, is to create several curve objects and to join them in a same group named 'curve_group' (this name is used in the following script).

Running the following python script will change the depth randomly from 0.01 to 0.1 :

import bpy
from random import uniform
for obj in bpy.data.groups['curve_group'].objects:
    obj.data.bevel_depth=uniform(0.01, 0.1)
    obj.data.bevel_resolution=5

Answer 3

If you like to do this procedurally, you can use Sverchok Add-On to quickly access those joined curves, get the points of each curve, regenerate them as NEW Curves all with random radius.

If you want to keep the original single Curve object with multiple Spline, you can really use Python and directly targetting the Bezier Point Radius. Visually shown here using Sverchok:

Thanks to SV Dev Zeff also we have this way to do it: