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Particle - shader question
Posted: 04 June 2012 07:50 PM   [ Ignore ]
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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

 

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Posted: 05 June 2012 04:19 AM   [ Ignore ]   [ # 1 ]
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Hi Moviehawk smile

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 smile

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particle_age.jpg
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Posted: 05 June 2012 08:02 AM   [ Ignore ]   [ # 2 ]
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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

 

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Posted: 05 June 2012 03:18 PM   [ Ignore ]   [ # 3 ]
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Moviehawk - 05 June 2012 08:02 AM

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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curve.jpg
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Posted: 07 June 2012 08:20 PM   [ Ignore ]   [ # 4 ]
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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.

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Posted: 07 June 2012 10:17 PM   [ Ignore ]   [ # 5 ]
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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.

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ParticleFade.png
ParticleFadeSh.png
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Posted: 08 June 2012 02:54 AM   [ Ignore ]   [ # 6 ]
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Hi Eximorph smile

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

smile

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Posted: 08 June 2012 09:31 AM   [ Ignore ]   [ # 7 ]
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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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