Hopefully someone that actually knows what they're talking about can assist me here, but the reason water is trickier with voxels (as far as I understand it) is because voxels aren't your typical 3D objects rendered by a video card. They're actually static objects that are data points displayed as 3D pictures - not
rendered. The distinction is important because when a video card has to render a 3D object it takes a bit of processing power. This is not true with voxels because, as mentioned before, they're just connected data points represented by pictures. There's almost no rendering involved so (with modern PCs) you can have literally infinite voxels on screen and experience no video lag.
Traditional 3D Objects:
- Movable, fully animatable
- More detailed = more rendering required.
- Lots of fancy, detailed 3D objects on screen = video lag.
Voxels:
- Immobile, no animations
- More detailed = no problem
- Infinite voxels on screen = no video lag
"But wait? Numerous videos have shown voxels being used to show destruction and chunks blowing off of walls/buildings/terrain."
You're right. That's because (again, as far as I understand it and I only stayed a Holiday Inn Express last night) voxels are connected data points rendered as pictures, and once those voxels receive the appropriate input they are replaced with traditional 3D objects that fully animate the destruction. EQNext is a combination of voxels and traditional 3D rendering (you can tell because the character models are most definitely not voxels).
So, finally, why does that make water tricky? I
assumeit's because you have to come up with a solution for setting huge areas of the game world as a certain 3D object (non-voxel) without taking a performance hit rendering it like you would a 3D character model. You can't comprise the water of voxels because they're static. They don't move. Even if you just simply turned off player clipping through the water voxels, I can't think of a way to simulate swimming through them. You'd just fall to the next set of voxels that had clipping.
Anyway, don't take that as the 100% god's honest truth because it's just my understanding of the tech after a few minutes of looking around to try to understand how it works.