Occlusion Culling Options

[Scott Richmond]

I'm prototyping a small 3D isometric game and I'd like to have the ability to drop in, for example, 30,000 cubes as a floor. Or really, any number of models and assorted items. But the point is - There would be lots over a large area. The question is, how can I cull unseen objects in an efficient manner from the render pipeline?

Using an isometric camera I'd only ever be looking at maybe 10% of the total amount of entities out there.

Would I:

1. Render all entities on the map and then try to cull them by:

1a. Using the LE2 OC - I've tried this and it appears very inefficient in general. I think the time its taking to traverse the entity list is larger than just rendering the primitive cubes I'm testing with. I also have heard that if I group entities together into larger chunks, it would help a lot. However I don't know how?

1b. Try to organise the entities into some form of octree and .hide() .unhide() them based on region.

2. Don't render everything in the first place. Only create and render the objects the player is looking at by keeping track of camera position. Delete entities as they fall out of range. But would this create lots of stutter as the player scrolls around?

 

Addendum: I also heard that, for example with these cubes I'm testing with, if I copy instead of create for each cube that helps? Any documentation on this?

 

Any other ideas? Tips on how to render faster?

[Canardia]

CopyEntity(cube) makes a new GPU instanced cube, so it's much faster than CreateCube.

 

For games with lots of cubes, the best is to remove all inner faces. You only need to do this once when a new cube is added or removed, so there is no FPS loss per frame, and the FPS gain is huge, since you then only have the outer hull left.

 

The easiest way to remove inner faces, is to check which faces are overlapping. This won't remove all inner faces, but at least half of them.

[Scott Richmond]

Agreed. And that approach can be taken further by stitching the cubes together and generating an outer shell as well. It is something I have thought about. But, I may yet still choose to go for a model approach if I'm not getting the quality I want with simple primitive cubes. And if thats the case, then I won't be able to apply such optimizations.

The game concept is fairly open-ended at this point.

[Scott Richmond]

By the way, just tested the Copy method. Works really well! 10FPS to 70FPS.

Would this method apply to models as well?

[Canardia]

LoadModel() does automatically CopyEntity(), when the same model is loaded more than once.

[Scott Richmond]

Ah great! I'll keep doing tests then I suppose.