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Manually managing octrees


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Considering a minecraft-style world, where "chunks" of static scenery are created and destroyed as the user moves around: 


Is it possible to manually manage the scene's octrees in order to keep picking fast? Notionally, I want to tell BJS: "Okay, I'm adding 50 meshes but they are all inside the following bounding box, so add a top-level octree and assume they're all in it."  And then later: "Ok, everything in the octree I added before is now gone."


Obviously I need to avoid processing the whole scene when doing this. Is this possible, or more broadly, is it the correct approach?

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You can easily pick an OctreeNode and add whatever you want inside. The Octree structure is pretty simple (I hope:))


1. Do you mean OctreeBlock?


2. Are there any docs/code samples? From the API I can see vaguely what's going on but many details are unclear.


3. Once you construct an octree how do you tell the scene to use it? Only API I can find is the one for auto-creating one.

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Thanks for the replies  :)


As for docs, I meant are there any code samples involving manual creation of Octree or OctreeBlock instances - the docs only cover automatic creation.


For example, both classes take in a creationFunc parameter, but what is it meant to be doing?

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Okay, by digging through the source I was able to get this working. For posterity, the code runs along these lines:


// octree for whole scene
var octree = new BABYLON.Octree()
octree.blocks = []
scene._selectionOctree = octree

// branch block for area from 0..100, 0..100, 0..100
var bmin = new BABYLON.Vector3( 0, 0, 0)
var bmax = new BABYLON.Vector3(100, 100, 100)
var branch = new BABYLON.OctreeBlock(bmin, bmax)
branch.blocks = []

// leaf block for area from 0..25, 0..25, 0..25
var min = new BABYLON.Vector3( 0, 0, 0)
var max = new BABYLON.Vector3(25, 25, 25)
var leaf = new BABYLON.OctreeBlock(min, max)

// add meshes to leaf


DK: Having gotten it working, it didn't actually turn out to help performance like I'd thought...

But I'll ask you about that in a separate thread.

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