Ephemeral effect

[zorak33]

i'm trying to make an effect where an object becomes visible only when a wave of particles washes over it. any ideas, tips, theories about how i might achieve this would be massively appreciated...

[atyss]

I suggest that you create grayscale particles. Render them alone as a pass. Use this pass as matte for the object you them you to reveal. For instance, the white particle will reveal the object, while the black pixels (not particles) will hide the object.

Hope this helps
Salutations - Cheers
Bernard Lebel

[zorak33]

Thanks for that Atyss... I'm a bit lost when it comes to the FX tree though. I've made a pass for the 'invisible' object which has a toon shader on it, and a pass for the particles.

How would you construct the FX tree so that the ink/toon rendered object is only revealed when the particles pass through it - should there be two seperate passes for the particles [colour and greyscale], and which operator/s?

I swear I've read the manual and looked for tuts but I'm seriously stuck and if I can get this sorted then the rest of my whole project/degree/life will all be downhill and there may be hope after all... [did I manage to convey the desperation factor here??]

Thanks again for any replies...

[atyss]

Yes, you did conveid the desperation factor. But I think you see the thing bigger than it is.

Import the two passes in the FX Tree.
Create an Over operator. Plug the toon pass in the right input on the top (the Foreground RGBA input), and the particle pass into the Obey Matte input (the blue input the right).

Then connect the Over node into a FileOutput operator.
It's simple as that.

Salutations - Cheers
Bernard Lebel

[zorak33]

okay, i think i've got things vaguely under control, although things seem to behave peculiarly now and again. thanks once again for your help...