• Maxon Cinema 4D

  Strange Behaviour – Ambient Occlusion On Hair Material Channel

  Posted by Alex Zeta on November 1, 2013 at 10:49 pm

  Hi,
  trying to create grass for a garden design, I just discovered a strange behaviour of ambient occlusion shader when applied to, for example, hair density channel.

  When i move/scale the plane where hair grows, it seems that hair distribution doesn’t refresh..
  See these two pictures (plane is also textured with ambient occlusion on color channel with gradient colors from red to blue, just to show that AO map applied to the plane is correct):

  First:
  

  Second:
  

  Could it be a bug or there is some rule that I am missing??
  Bye,

  Alex

  Brian Jones replied 12 years, 11 months ago 3 Members · 9 Replies
• 9 Replies

• 

  Brian Jones

  November 1, 2013 at 11:53 pm

  what version of C4D? it seems to be working as expected in 15
• 

  Alex Zeta

  November 2, 2013 at 7:43 am

  Hi,
  It’s r14..
  Alex
• 

  Brian Jones

  November 2, 2013 at 4:00 pm

  I’m seeing strange behaviour, if I make it in 14 I get this

  

  if I make it in 15 I get this

  

  If I open the one from 14 in 15 I get the same extra hairs in the centre. You might be too but I’m only seeing them since I am using a transparent cube. Either way if I move the cube the hair is gone where it should be. Something else must be affecting it, can you post the file?
• 

  Adam Trachtenberg

  November 2, 2013 at 4:14 pm

  It’s working fine here in R14 & R15.
• 

  Alex Zeta

  November 2, 2013 at 5:04 pm

  Hi Brian,
  I will able to post the file in a few days.. and did you try to move the plane (not the cube) to see if hair behave correctly?
• 

  Brian Jones

  November 2, 2013 at 7:03 pm

  Ah, you are right I have been moving the cube, when I move the plane I see the same as you, so far I don’t see a way to break that.
• 

  Brian Jones

  November 2, 2013 at 7:20 pm

  even if I clear the AO from the Density channel apply another effect/surface then put AO back in it still retains the original AO…
• 

  Alex Zeta

  November 3, 2013 at 6:19 pm

  Hi,
  yes… it seems the AO map won’t refresh..
  Did it work in R15?

  By the way, I’m attaching the file..
  Alex
• 

  Brian Jones

  November 3, 2013 at 9:45 pm

  it did not work in 15, it appears the hair material stores the channels like density and length internally, just guessing but I think when they were developing hair it made sense to lock them so your hair ‘styling’ didn’t move around. I just tried with a noise in World space and that gets locked too and moves with the plane instead of staying locked to world space. Don’t know a way around it, same thing happens in the Length channel

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