Water Exclusion Volumes

[Geenz]

These are functionally similar to, but different, from #3455. This takes the idea, and extends it to a full volume which is useful for interiors of underwater structures.

The basic premise is to to have a volume, such as a box or sphere, that when the camera is inside of it excludes water from rendering just in that volume. The idea is that if the volume is not intersecting a water plane, the water plane should continue to render. If the plane intersects with water fog, then only the intersected part of the water fog should not be rendered.

Test Plan

• Rez a cube.
• In the cube's features tab, tick the "volume" tickbox (final location TBD)
• Set the shape to "box"
• Set the volume to "water exclusion"
• Intersect the cube with water
• Note that fog behind the volume renders, but does not render inside the volume
• Note that the water plane renders behind the volume, but not inside of the volume
• Pass if both of the above two conditions are true

[Quinn-Elara]

Worth noting that it'd be great if old invisiprims were implicitly made into Water Exclusion Volumes in the interests of preserving legacy content functionality, however a toggle as described in the Test Plan (similar to Reflection Probes I guess?) should be the method going forward.

[DarlCat]

Worth noting that it'd be great if old invisiprims were implicitly made into Water Exclusion Volumes in the interests of preserving legacy content functionality, however a toggle as described in the Test Plan (similar to Reflection Probes I guess?) should be the method going forward.

If my understanding after reading the related similar proposal #3455 that making invisiprims fall into this new system it would change how existing content works so I don't know if that is as good of an idea as one might first think. The related proposal already covers restoring existing content in a near identical way to how it behaved before.

[Geenz]

Diagram visually showing the difference between this and #3455

[Geenz]

@Quinn-Elara @DarlCat #3455 is more or less the attempt to bring back existing invisiprims but just for water. We don't have a great way to handle the volumetric properties there on any arbitrary object for this with those things, so the idea is to at least make it work like it did for invisiprims to start with #3455 which excludes things from the perspective of the observer.

Volumes have different properties - you're saying "this doesn't exist within this volume, and only within this volume" rather than the perspective of the observer having anything to do with it. They would also take longer to implement (new prim parameter, would need support on the server, needs UI work), so #3455 gets on the board first so we can at least make existing content function again.

[canny]

This issue has been linked to a Canny post: Invisiprims 🎉