AWS Thinkbox Discussion Forums

1.6.80.45001 - PRT Hair Viewport Spacing

Deprecated Krakatoa MX Beta Bug Reports
#1

Increasing View Spacing to high numbers does not decrease the viewport amount of particles for me (when Entire Scene HairFur is selected)

However, decreasing it to low values when it comes close to 0 does slow it down for a few moments.

It worked with a single spline before, but not Hair Fur.

HairLimit does work though.

Win7
Max2012
Kraka 1.6.80.45001

#2

It works for me in spline and hair&fur.

I don’t have the PDV error you are getting either.

Password: KRA_Beta
vimeo.com/27953419

Ahh but I think I know what you are talking about, how many steps do you have in your splines/hair, obviously distribution would seem to be related to knot count. If you match your hair to the source for example and enable Vertex Ticks you will see that you can go no lower than the amount of wertx ticks on the originating spline object.

Example:
Orange is the base spline object with Vertex Ticks enabled. Blue is the PRT Hair at a VP spacing of 10.0 and 1.0.

#3

As JohnnyRandom mentioned, the PRT Hair object will always place a particle on the knots of the source spline no matter what spacing setting you choose.

#4

ah ok,

it would be cool if theres an option to put particles not on every, but every 2nd, 3rd, etc.
for cases where spline is very dense but dont want that many particles

also might be interesting having options like interpolate spline modifier does, letting user choose the interpolation method and how dense spline is just for the krakatoa prt hair, not changing the spline itself

#5

So if the points are always on the knots, wouldn’t that yield an uneven density along the spline? Or is there a density weighting to compensate for particles being too dense near the knots?

#6

The scheme for seeding particles in PRT Hair is as follows:

  1. It solves for where a particle would be placed in order to be “spacing” units away from the last particle.
  2. If the view adaptive controls are enabled, it solves for the pixel distance between this point and the last particle. If it exceeds the specified pixel spacing, the particle is placed to make it exactly “pixel spacing” pixels away.
  3. If the chosen position has crossed into the next spline segment, the particle is forced to be placed at the end of the current spline.

So its essentially the lessor of the “spacing”, “pixel spacing” and current spline segment’s length.

The PRT Hair system sets the Density of the particle to the inverse of the inter-particle spacing in order to accommodate varying seeding density. Its not exactly perfect, but it appears to be close enough from an empirical perspective.

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