Here is an approach with the Hair Particle System:
I made it mainly because I wondered if you can render the animation in Eevee and how long it will take to render a short animation. The problem is that the emission requires a baked light probe and it's static, not dynamic.
The modelling is quite simple:
- create a sphere. Remember its face count (as shown stastic text overlay and status bar). It's 386 in this example.
- apply the Scale to the object with Ctrl+A in Object mode if you have scaled it. The settings in this example are for default cube size (not scaled).
Enough modeled. Now the hair settings:
- add a Hair Particle System to the sphere object
- adjust the Emission settings:
- Emission > Number set this to the
face count of your sphere object
- ... > Hair Length and ... > Segments as you desire. Less segments makes the tentacles stiffer, more makes it more tentacle-ish. Try
1 m to 4 m and 5 to 10 segments.
- set ... > Source > Emit From to
Faces (default) and ... > ... > Particles/Face to 1
- enable
[X] Hair Dynamics. The ... > Structure > Stiffness value here also can be used to make the hair stiffer.
- Cache: if you have more than one ball give the cache a unique name. Double-click or Ctrl+click the first nameless entry in the list
- Render > Path > Steps: increase the number to
4 or 5
- Viewport Display > Strand Steps: use the same number as for the Render above
- Children:
None if you want to have fat tentacles like the little ball on the screenshots -or- Simple if you like hairy ones like the big ball on the screenshots.
- if you want hairy tentacles and used
Simple then
- try
20 for Children > Display Amount and ... > Render Amount and
- a ... > Radius of
0.3 m (depends on the size of your sphere)
- increase the the ... > Clumping > Clump value to something near 1 like
0.950
- use ... > Clumping > Twist if you like (
0.557, screenshot #3)
- experiment with the Children > Roughness settings if you like the hair strands rough and a bit messed up
- the Hair Shape section is important
- set ... > Strand Shape to a negative value like
-0.5 to have a thicker strand. It affects the thickness along the root to the tip.
- set ... > Diamenter Scale to
0.3 for fat tentacles (no children) or `0.05' for hairy ones
- last but not least, you can play around with the Gravity. Decrease it if the tentacles bend downwards to much (kinda like stiffness).
Render Settings
- set Eevee > Hair > Hair Shape Type to
Strip. This way you see in the viewport what you get when you use Cycles.
- for fat tentacles set Cycles > Hair > Shape to
3D Curves
The shader is simple. It's the Hair Info node and a Color Ramp node. With two Math nodes you can rotate the color ramp for a pulsing effect. With the Hue Saturation Value node the colors can be changed, and you can mix them. A Noise texture for the Emission Strength gives an interesting effect.
For the glowing I've used two Glare nodes (Ghosts, low, 2 it. & Streaks, high, 3 it.) in the Compositor. In Eevee it's a bit darker compared to Cycles. But it works, looks not that bad and is a lot faster (~15sec vs ~2min).
Cycles render:
Eevee render:
The settings for the right ball were changed a bit. Both have a Point light in the middle now, and Material Settings > Settings > Shadow Mode is set to None. For the lights Custom Distance is activated and set to 3 m.
This is to fake the light in Eevee. It's ok as long as there are no noticable reflections in the environment.
