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Bug with directional lights and translucent sprite material (w shadows)

No matter what I do, every time I try to light a translucent sprite material with a directional light my sprite gets strange, black artifacts when I enable volumetric shadows. I'm pretty sure this is a bug or maybe it has something to do with self shadowing? I'm not sure.

Any help would be appreciated. alt text

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asked Mar 22 '15 at 05:40 AM in Rendering

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Johnny Galvatron
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Hi Johnny,

This is not actually a bug, but an artifact of using "cast volumetric translucent shadows" with highly opaque objects.

alt text

The better course of action here is to use a masked material to generate correct shading.

alt text

I hope this helps.

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answered Mar 24 '15 at 02:22 PM

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Tim Hobson ♦♦ STAFF
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avatar image Johnny Galvatron Mar 24 '15 at 03:57 PM

Does this mean I cannot have a sprite that appears to "glow," with high transparent edges, yet casts a shadow?

avatar image Tim Hobson ♦♦ STAFF Mar 24 '15 at 05:29 PM

You can use the emissive input to get your sprite to "glow." In the examples below I just used the base color of my texture plugged into a multiply with a constant value of 1 in pin B. I then plugged the multiply into the emissive slot.

Here are the results and the problems that come with that.

Everything appears without the artifacts that cast volumetric translucent shadow causes. alt text

The problem comes in shadows. Since it's using an emissive material shadows will hide the artifacts, but make it not possible to cast shadows onto your sprite. alt text

glow1.png (318.3 kB)
glow2.png (211.5 kB)
avatar image Johnny Galvatron Mar 25 '15 at 01:31 AM

Thanks for your help Tim! You've been great!

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