factory compounds, now where is the fun in that?

From: Dan Yargici 
Sent: Tuesday, March 05, 2013 9:53 AM
To: [email protected] 
Subject: Re: Emit particles from camera FOV

You all know there's a factory 'Test Visibility From Camera' node, right?  :) 

DAN



On Tue, Mar 5, 2013 at 8:13 AM, <[email protected]> wrote:

  Do check the recent “ICE test vector inside cone” thread here – that should 
provide the basis for solving camera frustrum, which you can use for anything, 
such as filter on emission.

  Also: simply model a frustrum box, constrained to camera, and use delete by 
volume.
  Wether or not deleting points plays nice with your pointcloud is a bit 
unpredictable. (see: all particles disappearing on random frames, bounding box 
of the cloud disappearing on random frames rendering the cloud unrenderable – 
shudders... ) 
  Other than that – I find delete by volume quite handy in optimising 
pointclouds – getting rid of stuff that’s not needed, not visible or just stray 
particles.


  From: Gene Crucean 
  Sent: Monday, March 04, 2013 10:58 PM
  To: [email protected] 
  Subject: Re: Emit particles from camera FOV

  Sheesh. Didn't even get a chance to try myself yet lol. This list can be 
pretty fast at times. 

  Thanks Vincent I'll play with it in a bit.



  On Mon, Mar 4, 2013 at 10:36 AM, Vincent Ullmann 
<[email protected]> wrote:

    maybe this could help:

    a compound that creates a Grid of "Pixels" in front of your connected cam, 
and orients them properly...

    now you just have to press "Strg+A" and "Strg+G" to create a Group of your 
scene.
    then: do a raycast from each point along its orientation (rotate vector + 
particle ori). (do this on emit)
    if you have all this on a simulated ice-tree it should add new particles 
each frame... so you clould "paint"

    Am 04.03.2013 19:22, schrieb Gene Crucean:

      Well it's a little more complicated than that because I need to "paint" 
with the fov :) 

      So the accumulation of particles over time is required.



      On Mon, Mar 4, 2013 at 9:08 AM, Alok Gandhi <[email protected]> 
wrote:

        Hmmm, I think I have done it once for an effect. The workflow was 
really not that straight. I was emitting particles from a ground mesh. As a 
first pass, I was writing a weight map on the geo based on the camera move, 
setting value of 1.0 for all vertex in fov and 0 for non-visible. Then I froze 
the weight map. And in the sim, I was filtering the emission by this weight 
map. 

        But there can be other simpler ways around it depending use case 
scenario. One way that I think of right off my head is to delete particles not 
in view. But this can be time consuming if you have high particle density and 
only a small part of it visible to fov.






      -- 

      Gene Crucean - Emmy winning - Oscar nominated CG Supervisor / iOS-OSX 
Developer / Filmmaker / Photographer

      ** Freelance for hire **
      www.genecrucean.com

      ~~ Please use my website's contact form on www.genecrucean.com for any 
personal emails. Thanks. I may not get them at this address. ~~






  -- 

  Gene Crucean - Emmy winning - Oscar nominated CG Supervisor / iOS-OSX 
Developer / Filmmaker / Photographer

  ** Freelance for hire **
  www.genecrucean.com

  ~~ Please use my website's contact form on www.genecrucean.com for any 
personal emails. Thanks. I may not get them at this address. ~~

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