Here trying a different approach for making little nasty creatures, this time using the FEM system of houdini for Soft Bodies.

The approach is basically to use the restP attribute which controls the "default" position of the solid object, so that the mesh will try to keep it's initial shape, but that value could be animated and updated inside the sim using a sop solver. That restP attribute can be defined by vertex so that it can be transformed using the pivot of the tetrahedrons, so a "local transform" per each tetrahedron could be achieved, in this case contracting or expanding.
Then the rest is up to the FEM sim.

HIP file of one Slug with some comments inside:
joleanes.com/uploads/3/0/6/8/30680865/slug_001.hip

A few videos i used for reference:
youtube.com/watch?v=nUbETibPwBo
vimeo.com/81994340

Now coming back with another fun experiment, this time procedural centipedes, i have to confess these ones are a little hard to watch, i feel a bit uncomfortable.

Similarly with the sentinels, i had to use some trails and make a curve out of them to deform the centipedes, but this time the trails are not made with the trajectory of particles, because i needed to make the body collide with the other centipedes, so this time a similar setup of the tentacles was used, several pieces joined together with some hard constraints, then the head will have a random movement and the other pieces will try to follow the piece above the chain.
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Then i take a distance value to feed the motion of the legs, those are controlled with an ik that uses a clamped sin equation for vertical movement and a sort of "zig zag" equation for horizontal movement.
And finally i use the path deform to deform the centipedes with the curves from the rbd simulation.

Then again doing some tech experiments for fun with the sentinels but this time in houdini.

First Step: doing the tentacles animations using some sin equations. and attaching them all to the sentinel head.

Second Step: doing some particle animations following a curve using the pop curve force operator, then some trails were created.

Third step: the trails were used to control the deformation several sentinels, one for each trail, i used again the path deform that i did in vex.

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There is still some collisions between the sentinels that have to be done, maybe the next time.

Now the next step of the experiments, put some collisions!. I got some cool advice from Hernan Llano to setup the constraints https://vimeo.com/hernanllano

Check the previous video showing the procedural animation:
https://vimeo.com/248069396

the next step was setting up the RBD sim, creating some hard and spring constraints, and then i made a sop solver with vex to inherit the movements of the animation.

No stretch behaviour for now, maybe later.

Good exercise for practicing encapsulation!, with that i mean a concept used a lot in object oriented programming, really good way to keep the scene neat, clean and organized:
https://en.wikipedia.org/wiki/Encapsulation_(computer_programming)

​Now here remembering some old nice tech exercises but now with the powerful Houdini.

3-Step Tentacle with full procedural movement and geometry.

First step, the tentacle movement made with only points, a vex wrangler was used for that using some neat sin equations.

Second step, the geometry of the tentacle was made using segments that can be copied several times, then they are merged and the thickness is changed along the axis with a ramp.

Third and final step, the vex path deform (vimeo.com/247656989) was used to deform the tentacle geo along the tentacle curve that was created using the points of the first step.

Hip File to Download:
tentacle_001.hip

If you want to know more about how i design tools, i am using a similar process used in "System Development Life Cycle" which is the process used for software development, at the end of the day doing stuff in Houdini is the same as programming, but with nodes and scripting.

So before i even open Houdini i write a document with the requirements and design of the tool. Then after that i make the implementation in Houdini. I have found that is the fastest and most organized way to develop tools because you are not wondering around in the middle of the process in Houdini to know what to do next, because everything is already planned from the beginning. If something big need to be changed in the middle of the implementation or afterwards it's better to go back to the design document and make the change there.

Here is the Requirements & Design document for the tentacle tool:
tentacle_requirements_design.pdf

Here a wikipedia link with some info about "System Development Life Cycle":
https://en.wikipedia.org/wiki/Systems_development_life_cycle

Check this tool that i have been working on as Lead Developer:

SmartRefs is a new advanced external reference plugin for Autodesk 3ds max. With this tool you can Reference external files but having the ability to modify and animate the objects from that reference, in a similar way of the references of Autodesk Maya, but even more advanced.

SmartRefs is more flexible and robust than the classic XRef tool, even with the improvements made in 3ds max 2016. This tool is designed for artists and teams of any size, to allow them to have a better pipeline where big scenes could be splitted in several smaller scenes working as a whole in a seamless environment.

In a nutshell, SmartRefs makes 3ds max production ready.

Visit SmartRefs website to know more:

http://www.smartrefs.com

So as you may notice i haven't been able to update these plugins in the website for a while, i have been having a lot of work lately with other projects and couldn't keep working giving support and updates of these free tools. So i decided instead to make the source code available for the public for those of you who want to play around with it or to make a build for the newer versions of 3ds Max.

You can download the code following these links in the "Source Code" section:

IKFKSolver
Animatable Pivot

The version 1.0.6 of the Animatable Pivot is now available. Some issues related to copying keyframes were happening in 3ds max 2015, they were fixed in this new version.

It can be downloaded here:

Animatable Pivot

The version 1.1.5 of the IKFK Solver is now available. A bug related to opening the Link Info Tab of the Hierarchy panel has been fixed.

The new version can be downloaded here:

IKFKSolver