to get something like this:
you have to follow these steps:
- Shift-A -> Curve -> Curve Spirals
If you don't have that menu, go to your preferences and check the add-on:
- change settings to:
- Shift A -> Curve -> Circle and make it bigger
- select your spiral -> object -> convert to mesh
- add skin and subdivision modifiers
- add curve modifier
- material setup:
video tutorial for modeling: https://youtu.be/Ea4T0VUUA-k
To save geometry, this could well be a place for a bump-map. The advantages of geometry, (or displacement-geometry at render time) over bump are roughly:
- Visible profile / external contour. Not the case here: the beading is tucked in.
- Parallax / occlusion.. where one bump conceals another. We don't have the viewing angle for that, here.
- Shadowing. Bump simulates the light-response of the surface, but the bumps don't cast shadows. The difference here is slight:
Left: Bump only, Right: Displacement only.
To use Bump, you would have to make a height-map of your beading. You could model your beading as shown by @Chris, and shoot a tileable map, as shown, for example, here. But as I was doing that, I thought it would be good to have at least a basic 'Beading' shader node-group, to generate the heights procedurally.
The group is based on a semicircular wave:
.. where, by Pythagoras,
Y = sqrt(Radius^2 - X^2). This could be done by putting a Ping Pong wave through a color-ramp, but then the rounded ends in 3D would be fiddly. (At the hemispherical ends,
Height = sqrt(Radius^2 - (X^2 + Y^2)).
The group looks like this, inside:
Sorry about the tangle, squishing into screen-capture doesn't help.
Eventually, in these examples, it's used like this:
The Gradient node is just to wrap X around the outside of the cylinder's Object Space. You could UV unwrap instead.
The interface isn't silky-smooth; that would take more nodes. Radius sets the thickness of the elements, Tilt: the slope, Length and Y-Scale work against one another.. the higher the Y-Scale, the flatter the ends of the elements. Floor raises a base-level from which the elements protrude, making gaps.
Between them, the parameters can achieve a fair variety of effects .. (All these are Bump only, no Displacement):
The top example puts the output of the group through a color-ramp, for the fancy detail.