Particle - shader question

MoviehawkMoviehawk Posts: 30
edited June 2012 in Carrara Discussion

Thanks in advance for any help.

Here' what I want to accomplish ...
Run a particle stream of spheres and have the spheres fade out after 2-3 seconds. Not the entire stream of particles - only the ones that have been in existence for the spec ...

Edit: Not sure what happened - message got cut off!!!

Fade out only the spheres that have been in existence for the specified time.
I know how to limit lifetime, fade out the entire emitter using a shader and change size over time.
But can't figure out how to make them fade away.

Thanks for any help.
Allen

Post edited by Moviehawk on

Comments

  • 3DAGE3DAGE Posts: 2,025
    edited December 1969

    Hi Moviehawk :)

    You'd use the ( Natural functions / Particle shader ) then choose "Age" as the variable.

    you can make a Mixer in the alpha channel, or transparency channel and use that ( particle shader / age) as the Blender of two values.
    and that will fade the particle out depending on it's age.

    Hope it helps :)

    particle_age.jpg
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  • MoviehawkMoviehawk Posts: 30
    edited December 1969

    Thanks .. I owe you a pizza.

    I keep forgetting the particle shader is located under natural functions(!)


    This works ... almost.
    Ideally I want the particle to run 4-5 seconds - with no fading, then fade out over the following 1-2 seconds.
    I'll have to keep tweaking.

    Thanks

  • EximorphEximorph Posts: 35
    edited December 1969

    Moviehawk said:
    Thanks .. I owe you a pizza.

    I keep forgetting the particle shader is located under natural functions(!)


    This works ... almost.
    Ideally I want the particle to run 4-5 seconds - with no fading, then fade out over the following 1-2 seconds.
    I'll have to keep tweaking.

    Thanks


    Use a curve filter on the particle shader. Adjust the curve to get what you want.

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  • MoviehawkMoviehawk Posts: 30
    edited December 1969

    Eximorph .. thanks for that tip, but I can't seem to get any results using that approach?? I must be doing something wrong - I'll keep trying.

  • EximorphEximorph Posts: 35
    edited December 1969

    Is this the type of effect you were trying for?

    In my second try I simplified the alpha channel. The particle age is modified by the curve filter so that for the first 70% of the lifespan will have alpha 100%. Then it will fall to 0% by the end of the lifespan.

    If you are interested in my test scene, PM me your email and I'll send it to you.

    ParticleFadeSh.png
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    ParticleFade.png
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  • 3DAGE3DAGE Posts: 2,025
    edited December 1969

    Hi Eximorph :)

    Nice solution.
    the curve filter can be a really powerful way to control the effect of shaders.

    :)

  • MoviehawkMoviehawk Posts: 30
    edited December 1969

    Eximorph .. that did the trick!

    Eximoroh, 3dage - you both get pizzas!

    Never used the curve filter before - opens up a whole new bag of tricks!

    Was just starting to try Shoestring Shaders proximity shader - a powerful tool with it's own WOW factor, but this gives me the result I was looking for.
    Applied the same concept to the glow channel and now I can get my particles to change glow color at midstream.
    Will have to keep experimenting.

    Thanks

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