Disable shadow casting per nif

[maniman303]

It would be cool to have an option to disable in specific nif through some flag shadow casting by this nif. Usage scenario could be that grass from mods could have shadows disabled to increase performance. Maybe implementation of BSLightingShaderProperty would do the work?

[AnyOldName3]

• We can't add this kind of thing before 1.0 dehardcoding as until then we're aiming for things that work in OpenMW to owrk in the vanilla engine. None of the 4.0.0.2 Nif fields mean This TriShape doesn't cast shadows, and OpenMW-specific stuff can use better containers than Nif.
• There are technical reasons why it's not really feasible to disable shadows per-Nif. It might be possible to enable them per-Nif, but that's less useful.
• Making it possible to disable shadow casting for groundcover will be something we definitely do when we settle on a groundcover system. As that's the main time it's reasonable to have something be visibly opaque but not cast shadows, it should cover most of the need for a Nif flag in the first place. It also has the added benefit that we can make it an engine setting, so people with especially powerful machines can keep groundcover shadows without having to install different mods.