Dynamic Hair with the Cloth Deformer

After a few drafts I’m getting encouraging results with dynamic hair.  This symmetrical hair was modelled lock by lock, each one layered over the other.  The roots of the hair fully conform.  From the side of the head down till below the ears is the falloff area then right down to the tips the hair is all dynamic.  It’s important to get the initial style right where the hair does conform because it will try to return to that shape during the simulation.


Improvements are needed in the number of layers of hair.  It needs another layer at the side of the head and one or more lower at the back of the head below the ears.  There should also be more variety in the locks – I duplicated and moved the same ones at the side of the head for each layer to save time.  The texture and transparency maps need more effort and care to paint with higher contrast in the strands and cleaner detail for the alpha on the tips.  I also made a scalp prop to fit underneath based on a copy of the figure’s head geometry.

I have shown animations before with dynamic cloth hair but these did not have self collisions or enough length to drape over the costume/figure.  This example used a large sphere on an angle to cover the whole head and the ears and a capsule for the neck.  The collisions over the costume required the modified code which can recorded and store simulations at a higher fps.


While working on this I found that the conforming falloff feature of my plugin wasn’t working quite how I wanted or expected.  It’s supposed to falloff gradually from fully conforming to fully dynamic with a painted map or zone or both – but there was not much ‘falloff’ apparent.  I made a slight change to the simulation code to improve this.  My idea is that if the falloff for a vertex is 50% then it will be pulled back half way from where the physics take it to the conforming position.  The conform rate value is now used as a speed limit instead.  The conforming force is still very strong but the falloff now produces a smoother transition.  Collisions overrule this so I will need to experiment a bit more.  I want this falloff because in cloth simulators that have an on/off pixel constrain selection this creates really obvious hard bends along that dynamic edge.  

I made another quite simple but important change to the plugin code and that was to add in a self-collision margin.  In my simulator each vertex of the cloth mesh is treated as a particle with a thickness.  Unless the user overides that thickness all of the vertex particles are thick enough so that they just touch each other.  That is one reason why a regular mesh is very important.  The new margin value allows for thinner vertices and now the cloth folds can get much closer.  The hair’s need to have self collisions become obvious because without this new change the dynamic locks would pass through and intersect with each other.  This has a big impact on the design and modelling the style because the hair must start the simulation without being tangled.

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