[Bf-committers] Similar Surface modifier

[Charles Wardlaw]

Hi,

Shrinkwrap is a very useful tool but doesn't behave in the same way.  
For starters, at certain spots it causes vertices to snap between  
positions, which causes interesting motion blur flubs. But more  
importantly it's not a binding method. I'm sure someone will correct  
me if I'm wrong, but shrinkwrap just casts rays down into the target  
mesh from verts. If you spin the parent mesh, the deformed mesh  
distorts like a monster in a plastic bag.

The wrap deformer is a binding method that would be like a permanent  
shinkwrap, binding high res geo to low res and allowing the deformed  
to change *with* the parent, not *around* it.

Also a wrap deformer shouldn't cause points to move onto the parent  
mesh. That would make a high res cage end up with the low res's  
blockiness.

That said, I bet parts of the shrinkwrap code could be repurposed as a  
starting point.

~ C


On 2009-10-29, at 9:13 AM, Daniel Genrich <daniel.genrich at gmx.net>  
wrote:

> Helo there,
>
> Does anyone here ever tried the "ShrinkWRAP" modifier? It was  
> especially
> designed for that purpose.
>
>
>
> Charles Wardlaw schrieb:
>> Sounds a lot like Maya's wrap deformer. LW has a nice one too-- you
>> can choose whether or not the deformer is calculated as hard bodies  
>> or
>> as skinned meshes. This makes it easy to use a series of cubes to
>> deform a set of high-poly train cars without the cars bending in the
>> middle. (Think it's called HardFX Linker? It's been a while.)
>>
>> It'd be an awesome addition to Blender, and not just for cloth. We
>> used it on a project at my last job to transfer animation from a low-
>> res mesh to a high res one, and also to transfer to a high-res fur  
>> cage.
>>
>> ~ C
>>
>>
>>
>> On 2009-10-29, at 8:59 AM, Roland Hess <rolandh at reed-witting.com>  
>> wrote:
>>
>>
>>> Hi folks --
>>>
>>> With Durian in progress, I wanted to share a thought I'd had with  
>>> both
>>> the artistic and development teams. Having tried to use the cloth
>>> sim a
>>> number of times in a production capacity, one of the critical
>>> shortcomings I've identified (and one that I'm sure you'll run into)
>>> is
>>> the deficiencies the system has with complex clothing designs. I  
>>> don't
>>> mean high poly counts, but places where in an actual piece of  
>>> clothing
>>> the fabric is layered: cuffs, the doubled ridge of cloth that runs
>>> down
>>> the front of an Oxford, pockets, lapels, etc.
>>>
>>> Obviously, there are workarounds, but I have a solution that I'm not
>>> going to have time to implement myself. I built the modifier  
>>> structure
>>> and basics, but once I realized I'd never coded with the modifier
>>> system
>>> or dealt with mesh data directly I realized that it would require  
>>> more
>>> time than I had, and would be fairly easily accomplished by someone
>>> already familiar with it.
>>>
>>> I think a good solution to this problem would be a "Similar Surface"
>>> (name for artists) or a "Hook Web" (name for devs) modifier. Simply
>>> put,
>>> the modifier is a "bind" type one, a la the cage deformer. The user
>>> creates a fairly simple structure upon which to run a cloth sim (or
>>> any
>>> other deform technique, actually). Then, the user creates their  
>>> "high
>>> res" clothing, which includes all the nice things like buttons,
>>> epaulets, cuffs, pockets, layering, etc. Clearly that would never
>>> survive an actual cloth sim. When the user BINDS the high res  
>>> clothing
>>> to the sim'ed simpler one, the following happens:
>>>
>>> 1. For each vert in the high res, a virtual hook is created. Within
>>> the
>>> modifier, it would be an array of hook objects (obHook). Hook data
>>> structure is deprecated in favor of the hook modifier, but the DNA  
>>> is
>>> still there.
>>> 2. Where does the virtual hook attach? The shrink wrap "nearest
>>> point on
>>> mesh" procedure is used to identify. Then, the verts that make up  
>>> the
>>> identified face of the underlying mesh become the vertex parents of
>>> the
>>> virtual hook.
>>>
>>> That's it. This would allow complex, multi-layered clothing to be
>>> driven
>>> by an underlying cloth simulation.
>>>
>>> From reading the DNA and modifier code, it appears that everything  
>>> is
>>> already there. We need someone who is familiar with mesh coding and
>>> modifiers to put it together. Unless I miss my guess, the Durian  
>>> team
>>> WILL be asking for something like this in the near future.
>>>
>>> -- 
>>> Roland Hess
>>> harkyman
>>>
>>> _______________________________________________
>>> Bf-committers mailing list
>>> Bf-committers at blender.org
>>> http://lists.blender.org/mailman/listinfo/bf-committers
>>>
>> _______________________________________________
>> Bf-committers mailing list
>> Bf-committers at blender.org
>> http://lists.blender.org/mailman/listinfo/bf-committers
>>
>>
>
> _______________________________________________
> Bf-committers mailing list
> Bf-committers at blender.org
> http://lists.blender.org/mailman/listinfo/bf-committers