Can strands receive shadows?

Support Compositing and Post Processing
#1

Hiya, does anyone know if strands are supposed to be able to receive shadows? (I thought that shadow buffers were supposed to work fine with them.)

I’ve got some particle grass being rendered as strands and an object casting a shadow on it from a spotlight set up with a shadow buffer. The shadow works fine on normal meshes, but won’t show up on the grass :S Any ideas why it might not be working, or what I could do to fix it?

I’ve googled and read a fair bit about strands and shadows but couldn’t find the specific info I was looking for. Hoping you can help.

Thanks

#2

The shadow buffer works by taking a ‘silhouette’ of the object based off of the lights position and then mapping a grayscale version of that onto all the objects. So if the shadow buffer doesn’t have a high enough resolution, the shadows won’t be able to show up on tiny stuff like strands. Which is one of the disadvantages of shadow buffer lamps.

#3

Thanks. That wasn’t quite what was going wrong but it pointed me in right direction. The spotlight’s shadow was set as an irregular shadow buffer. Apparently strands can’t recieve or cast this kind of shadow map. Setting it to a nice high res (thanks for the tip) classic shadow buffer sorted it. Probably should have thought of trying that to begin with.

Oh well, here’s a (slightly) pretty picture with a shadow in it to compensate you somewhat for you time.

And incase anyone’s intersted here’s a link to the tutorial I was following. I expect everyone’s seen it already but still. Eh and seeing as I’ve discovered how to upload attachments, here’s the blend file too.

Attachments


glslshaders_02_softbody_01_grass_01.blend (933 KB)

#4

Looks excellent

#5

Thanks : ) The purple thing has got soft body physics on it.