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Chrysley
02-19-2008, 05:44 PM
Is there a way to generate the particle based on the speed of a a surface it will generate from?

I have a sea surface and I want to generate foam and spray based on the speed a particular part of the surface is moving. I want those parts that move the fastest to generate foam/spray. Is there a way to do a speed test on the geometry and then give birth to particles without having to generate particles first on the surface?

joconnell
02-19-2008, 06:01 PM
You could do a speed test on particles locked to the surface and then birth from them, otherwise you'd need something like box #3 or a script operator. Another way to think of it is to use whats driving the sea surface - if it's a map being used to displace the surface upwards then you'd probably be able to use the texture to drive a volume select and birth on selected faces or alternatively use a birth emission map. Also if the surface is moved upwards you could use another volume select to grab the peaks and emit from those.

PiXeL_MoNKeY
02-19-2008, 06:08 PM
Another idea is do a top down render of the velocity element, camera map to the geometry and then use that to emit the particles based on the velocity colors.

Just a thought,
-Eric

Chrysley
02-19-2008, 07:23 PM
Another idea is do a top down render of the velocity element, camera map to the geometry and then use that to emit the particles based on the velocity colors.

Just a thought,
-Eric

Great idea! Although, how do I render a velocity map of the surface from above? It might be in the render effects, but I could be wrong. I have to check when I get back home. Thanks!

Chrysley
02-19-2008, 07:31 PM
You could do a speed test on particles locked to the surface and then birth from them, otherwise you'd need something like box #3 or a script operator. Another way to think of it is to use whats driving the sea surface - if it's a map being used to displace the surface upwards then you'd probably be able to use the texture to drive a volume select and birth on selected faces or alternatively use a birth emission map. Also if the surface is moved upwards you could use another volume select to grab the peaks and emit from those.

I've used the volume select method to generate from the peaks and inherit it's motion but it doesn't seem to have a realistic transition when composed together. I'm guessing it might be because it's only accounting for the motion of the peaks and not the actual wave motion as a whole. And I have a rather realisitc sea motion so it doesn't blend well.

PiXeL_MoNKeY
02-19-2008, 07:34 PM
Place an Orthographic Camera above the surface, Render Elements > Velocity, camera map output from the camera it was rendered from.

-Eric

Chrysley
02-19-2008, 07:41 PM
Place an Orthographic Camera above the surface, Render Elements > Velocity, camera map output from the camera it was rendered from.

-Eric

*smacks head*
Thanks man! You're awesome! :)

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