CGTalk - nCloth "Mass" - Any relation to real world mass/weight?

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FluidEdge

11-01-2010, 12:42 PM

Can anyone help me out with how nucleus calculates mass and how this figure relates to real world mass of a cloth garment?

The nucleus white paper states that "in terms of physics, the mass does not need to be in the real world units for proper collisions as long as the relative values are the same"

and

"there are two factors that make mass setermination more complex: air resistance and point density"

So point density I understand to be the ratio between number of faces and number of CVs.

We can easily work out the surface area of a mesh, so given a known mass of cloth, can we translate this into an "nMass"?

john_homer

11-01-2010, 09:03 PM

mass is per point (vertex/particle) not area.
$mass * $vertCount = $garmentMass

FluidEdge

11-02-2010, 08:19 AM

so a garment weighing 500g with 7000 verticies should have a 'mass' of 500/7000 = 0.0714?

Since mass is so important in the nucleus solver calculations, getting this right at the start with a calculation is very useful. Is there nothing about surface area/scene scale involved in the calculation though?

I wonder if Duncan can shed any light on this and give us the calculation.

FluidEdge

11-03-2010, 12:17 PM

OK this mass calculation is not accurate. Can anyone shed any light on how the mass attribute is calculated?

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