Light shadows when using alpha texture


i am wondering if casting shadows from a light on a geo with a phong MAT using an alpha textured shape is possible ?

Basically, i am using a rectangle SOP on which i apply a circle texture (black and white) to cut a hole inside it. Phong MAT is set with alpha ON. A filled rectangle is placed behind this layer as a background on which i try to cast a shadow from the hole.

Using a light on that geo works as expected but as soon as i turn shadows on, the hole turns black.

I don’t know how it works under the hood, but it seems like shadows are not possible through an alpha textured SOP right ?

Of course it is working if i import a 3D rectangle mesh with a hole inside.

See attached file : turn shadows on/off in the lightCOMP

Using TD 2020.25380 under macOS Mojave 10.14.6

Thanks a lot.

alphaShadows.tox (3.1 KB)


You were really really close!

You need to go to each phong and set the alpha par to “Discard Pixels Based On Alpha” to True

Next you have to turn the shadows on in the light:

I pushed the res until you can’t see bumps in the shadow, (or your system starts to drag)

alphaShadows.tox (3.3 KB)