View Full Version : mia material alpha channel + nParticles = rendering issue.

07 July 2009, 07:25 PM
hi, actually i am in a proyect where i need to create a fountain, and i need to export an alpha channel for composition, problem is simple... look at these images, whats strange here...

yeah, exactly the nParticles water shader are messing up with the other shaders and surfaces, but why? why is it? what property is messing up this? i dont want the water creating that alpha channel, i want the water as solid color, yeah, casting refractions, but not alpha channels...

i guess that is the problem are the nParticles because the settled water in the bottom has the same mia material shader, the water in the top is exactly what i want: water with no alpha at all even when it has some refractions, but it is an animated polygon mesh by real flow.

so i really think that the issue is with n particles and mia material... but why and what...

04 April 2010, 04:55 PM
have you found a solution to this? this is bothering me as well...

04 April 2010, 05:13 PM
is propogate alpha checked in your mia_material? try switching it.

i've found that with refractive materials, a lot of the time it's best to create a separate render layer to handle the refracted mattes. for example, you could put a plain blue surface shader on your stone fountain surface, and a transparent, non-reflective material with the same refractive index of your liquid on the liquid in order to refract the blue material, which you could then use as the fountain's alpha channel in compositing. does that make sense?

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04 April 2010, 05:13 PM
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