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(sparse + dynamic) 3D spatial representation structure for fast searches

branch: master
README.md

threeoctree.js (r60)

(sparse + dynamic) 3D spatial representation structure for fast searches

The aim of this project is to create a fully featured search tree for the THREE.js WebGL library.

This build is stable up to THREE.js ~r60
(see migration notes below, updates to latest THREE build coming!)  

Features (+ Example)

  • handle complete objects ( i.e. 1 center position for entire geometry )
  • handle object faces ( i.e. split a complex mesh's geometry into a series of pseudo-objects )
  • handle both objects and faces together in a single octree
  • overlaping nodes to help sort objects that overlap multiple nodes much more efficiently ( overlap is percentage based )
  • split ( 1 larger octree node > up to 8 smaller octree nodes )
  • merge ( up to 8 smaller octree nodes > 1 larger octree node )
  • expand ( 1 smaller octree node > 1 larger octree node + original smaller octree node + up to 7 other smaller octree nodes )
  • contract ( 1 larger octree node + entire subtree > 1 smaller octree node )
  • rebuild ( account for moving objects, trade-off is performance and is not recommended )
  • search by position and radius ( i.e. sphere search )
  • search by ray using position, direction, and distance/far ( does not include specific collisions, only potential )
  • raycast search results using built in THREE.Raycaster additions ( does not modify the Raycaster except to add new functions )

Needs

  • reworking / optimization of insert and removal ( currently we have to force a transform update in case the object is added before first three update )

Migration

r56 → r60

  • Octree can now handle vertices (and particle systems)
  • add method now takes a options object as the second parameter, which may contain booleans for useFaces and useVertices
  • OctreeObjectData.usesFaces removed, use .faces, .face3, or .face4
  • OctreeObjectData.getFaceBoundingRadius split into .getFace3BoundingRadius and getFace4BoundingRadius
  • OctreeObjectData.vertices added
    #### r51 → r56
  • Function naming conventions from hello_world() to THREE style helloWorld()
  • Script renamed from ThreeOctree.js to threeoctree.js
  • Ray.intersectOctreeObjects/intersectOctreeObject to Raycaster.intersectOctreeObjects/intersectOctreeObject
  • Vector3/Matrix4 functions from THREE r51 to r56 ( see: https://github.com/mrdoob/three.js/wiki/Migration )

Usage

Download the minified script and include it in your html after the THREE.js WebGL library.

<script src="js/three.min.js"></script>
<script src="js/threeoctree.min.js"></script>

Initialize

var octree = new THREE.Octree({
    radius: radius, // optional, default = 1, octree will grow and shrink as needed
    undeferred: false, // optional, default = false, octree will defer insertion until you call octree.update();
    depthMax: Infinity, // optional, default = Infinity, infinite depth
    objectsThreshold: 8, // optional, default = 8
    overlapPct: 0.15, // optional, default = 0.15 (15%), this helps sort objects that overlap nodes
    scene: scene // optional, pass scene as parameter only if you wish to visualize octree
} );

Add/Remove Objects

Add three object as single octree object:

octree.add( object );

Add three object's faces as octree objects:

octree.add( object, { useFaces: true } );

Add three object's vertices as octree objects:

octree.add( object, { useVertices: true } );

( note that only vertices OR faces can be used, and useVertices overrides useFaces )

Remove all octree objects associated with three object:

octree.remove( object );

Update

When octree.add( object ) is called and octree.undeferred != true, insertion for that object is deferred until the octree is updated. Update octree to insert all deferred objects after render cycle to makes sure object matrices are up to date.

renderer.render( scene, camera );
octree.update();

Rebuild

To account for moving objects within the octree:

octree.rebuild();

Search

Search octree at a position in all directions for radius distance:

octree.search( position, radius );

Search octree and organize results by object (i.e. all faces/vertices belonging to three object in one list vs a result for each face/vertex):

octree.search( position, radius, true );

Search octree using a ray:

octree.search( ray.origin, ray.far, true, ray.direction );

Intersections

This octree adds two functions to the THREE.Raycaster class to help use the search results: .intersectOctreeObjects(), and .intersectOctreeObject(). In most cases you will use only the former:

var octreeResults = octree.search( rayCaster.ray.origin, rayCaster.ray.far, true, rayCaster.ray.direction )
var intersections = rayCaster.intersectOctreeObjects( octreeResults );

If you wish to get an intersection from a user's mouse click, this is easy enough:

function onClick ( event ) {

    // record mouse x/y position as a 3D vector

    var mousePosition = new THREE.Vector3();
    mousePosition.x = ( event.pageX / window.innerWidth ) * 2 - 1;
    mousePosition.y = -( event.pageY / window.innerHeight ) * 2 + 1;
    mousePosition.z = 0.5;

    // use THREE.Projector to unproject mouse position into scene via camera

    var projector = new THREE.Projector();
    projector.unprojectVector( mousePosition, camera );

    // create new ray caster
    // origin is camera position
    // direction is unprojected mouse position - camera position

    var origin = new THREE.Vector3().copy( camera.position );
    var direction = new THREE.Vector3().copy( mousePosition.sub( camera.position ) ).normalize();
    var rayCaster = new THREE.Raycaster( origin, direction );

    // now search octree and find intersections using method above
    ...

}

Copyright (C) 2012 Collin Hover
Based on Dynamic Octree by Piko3D and Octree by Marek Pawlowski
For full license and information, see LICENSE.

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