Parts that have the cast shadow property set to true will no longer be respected by game lighting if their transparency is set to 0.75 or higher (0.74 and below does not cause this effect)
Example images:
(ignore the light cast through the other windows which have the property disabled and are not the target of these examples.)
0.7 transparency:
The cast shadows property should be respected irrespective of its transparency property value. This is vital not only to give creators more control over their experience and to avoid confusion, but also because transparent parts can create shadows for creating dark environments without needing a visual obstruction that can detract from the immersion in the experience.
I agree but there are limitations to the Roblox Lighting.
Transparency is a big one since the variation of that alone causes semi-transparent items behind other semi-transparent items to overlap.
This seems to create issues with the rendering engine displaying the closest Position item to render in front, even if the one at the further Position is larger and in front of the closest one.
I imagine that shading through semi-transparent issues causes a lot of excess work for the Roblox graphics engine design.
While I can imagine this feels like unexpected behavior, parts not casting shadows beyond a certain transparency threshold is done intentionally. Ideally these types of parts would only cast very subtle shadows like they do in real life, but this is not something we support today.
I’ll track this as a feature request for now so we can consider it for future lighting improvements.
