More old cloth wind resistance stuff.

Haven't posted in a long time, easing back into it with something I was playing with about a year ago ... it uses the same wind resistance stuff that I was using earlier.

Going to update it in the next few days with a much better way of doing it with a SOP solver!

Houdini - Cloth paper thingy from Sam Hancock on Vimeo.

Each piece of cloth is simmed individually, a wedge ROP is used to write out a geo sequence for each piece and they are brought back in using a file SOP and a copy SOP. The pieces don't collide .. but it doesn't matter so much with these .....

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Some SOPs edges and poly line business

Every time I go to extract the border from a mesh I always end up using some strange combo of Group unshared edges, delete and dissolve, I came across a good way of getting unshared edges that I haven't thought of before, and now it seems really obvious ... using the polycap node to trace the border and then deleting all of the source prims, works like a charm! I have also usually had trouble with splitting up a line into multiple primitives, here is a way to create a primitive per edge. This example only works if every point has 2 neighbours but could easily be modified with a copy SOP to allow a dynamic amount of neighbours. (instead of 2 vopsops and a merge to duplicate the points). It works like this: The point number is stored in an attribute to create a unique number for each point The whole mesh goes into 2 streams to duplicate every point. For the first set of points, each point gets the point number of the first neighbour and applies a cantor func...

Worm locomotion with FEM

I have always wanted to do a dynamic locomotion setup, I have tried in the past with wire and sop solver with .... interesting results ;) With FEM in Houdini 13, the rest attribute is stored on vertices which allows a tetra to change its rest state independently of the surrounding tetras. With this, parts can be expanded and shrunk to get a muscle type action. I have started with a worm since it is quite simple, the contractions and expansions move back along the worm in a wave, opposing the travel direction. It took quite a bit of tweaking to get him moving at all. One major element of a real worm's action that's missing is the little hairs that grip the ground. I couldn't find a way to change the friction per point so I have gone a bit hacky and multed down v wherever I didn't want the worm to move. I would love to hear if there is a per point friction control! Here is the video Houdini 13 FEM Worm locomotion from Sam Hancock on Vimeo . ...and the .hip is...

Wire to RBD feedback in DOPs

Normally if a wire is constrained to an RBD, the rbd isn't affected by the wire at all. Which is annoying ... but I had an idea to get it to work. the wire solver can store the internal forces on the geometry. In DOPs I made a point force, the position is set to the position of the constraint and the force is the wire's internal (linear) force. I have put a sopnet in the dopnet to get the wire and the constrained point so I can reference them in the point force. It could be simpler with a python expression to get the position and force directly without going through the sopnet, but this is just a little test... For multiple attachment points, I think a copy data node could be used to copy the point force data for each constrained point ... hip file here Wire to RBD feedback forces from Sam Hancock on Vimeo .

I, Houdini

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