occlusion culling bump...

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acornco
Posts: 1
Joined: 21 Apr 2021, 03:14

occlusion culling bump...

Post by acornco » 21 Apr 2021, 03:48

so ive been playing around on open microwave, gj.

and ive been turning up the cells...

and ive been watching my frame rate drop. its worth it. but, is the drop necessary?

well it is if the engine draws every flipping cells geometry, textures and lighting within a mile of the camera....

i read this old thread...
viewtopic.php?t=5573&start=10

and its both right and wrong. running occlusion culling on standard 1 cell morrowind dosnt make sense. but it starts making alot more sense with more cells or considering games with more complex geometry, texture depth and surface lighting.

i think part of the issue, concerning morrowind, is to think out side the box.... rofl. i think i read somewhere that one of omw's mission statements was to exceed the original engine; not just accomplish parity.

so, off the cuff... morrowind already uses "portal" culling, you could just as simply say "dont load cell "a" if player is at coords xyz." because at those coords and or under that height, the player cant see over mountains/builings/etc.

thats not really a great idea as it would be specific to morrowind... but just rolling over dosnt help.

"obviously"........ it dosnt really matter since advancements in processing tend to gloss over poor programming.

i just like to stir the pot.

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AnyOldName3
Posts: 2111
Joined: 26 Nov 2015, 03:25

Re: occlusion culling bump...

Post by AnyOldName3 » 21 Apr 2021, 20:52

We don't have defined occluders in Morrowind's data so can't do any good CPU-side occlusion culling. GPU occlusion culling introduces pop-in as query results are a couple of frames out of date. You can work around that by drawing things that you think might be visible, but can only guarantee no popping by drawing everything, which defeats the object of having it in the first place.

The original Morrowind engine absolutely did not have portal culling - that came with one of the later BGS games. Also, portal culling only works if you've got distinct rooms that are separated by walls and you know where all the holes in those walls (portals) are. If someone made a mod that put walls at cell boundaries, maybe outdoor portal culling could work, but then there'd be no point having a long viewing distance as there'd be walls in the way of anything far away. What you've described isn't portal culling.

However, it's fairly similar to a work-in-progress merge request that exists - https://gitlab.com/OpenMW/openmw/-/merge_requests/227 generates occluders from the terrain which we can use for culling. It's got some problems so far, though.
AnyOldName3, Master of Shadows

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