Three js RayCast between two object in scene - three.js

I know how raycast object in scene when click on mouse, but now i need to know if two object in scene can raycast each other.
This is, i load a 3D Object in scene for example Two Rooms in OBJ object, then i add three mesh box in some points, for example two point on first room and one point on second room.
Then two points on first room can raycast each other(have direct vision), but two point for first room can't raycast point on second room.(they don't have vision through room wall).
I attached code used for load scene and points, any sugestion hwo to do?
//LOAD MAIN 3D OBJECT
var objLoader = new THREE.OBJLoader();
objLoader.setMaterials(materials);
objLoader.setPath('./asset/3d/');
objLoader.load("model01.obj", function(object){
var mesh = object.children[0];
mesh.castShadow = true;
mesh.receiveShadow = true;
mesh.rotation.x = Math.PI / 2;
var box = new THREE.Box3().setFromObject( object )
var ox = -(box.max.x + box.min.x) / 2;
var oy = -(box.max.y + box.min.y) / 2;
var oz = -(box.max.z + box.min.z) / 2;
mesh.position.set(ox, oy, oz);
_scene.add(mesh);
render();
setTimeout(render, 1000);
}
//LOAD count_points inside scene
for(var i=0;i<cta_points;i++){
var c_r = 2;
var c_geometry = new THREE.BoxBufferGeometry( c_r, c_r, c_r );
var c_material = new THREE.MeshLambertMaterial( { color: new THREE.Color("rgb("+(40 + 30)+", 0, 0)"),opacity: 0.0,
transparent: true} );
var c_mesh = new THREE.Mesh( c_geometry, c_material );
var position = get_positions(i);
c_mesh.position.copy(position);
c_mesh.name="BOX";
scene.add( c_mesh );
}

Possibly take a look at:
How to detect collision in three.js?
Usually, to solve this problem, you would make a collision mask with a collision group.
The collision group is added per object, and is represented by a "bit" in a bitmask,
The wall could be in a separate collision group, like 4 (binary 100)
and the objects could be in another group, say 2 (binary 10)
Then you just need to check collisions of the object against the mask.
(check if the collision group matches against a bitmask (the masks above could be 10, 100,) to check for collisions).
So that way, you can call THREE.Raycaster().intersectObjects(args), where the arguments are the ones that pass the bitmask test ( mask == object.collision_group ).
That way, you won't need to include the wall for collision detection testing, since it is using a separate bitmask.

Related

three js LoadObject pivot [duplicate]

What I'm trying to achieve is a rotation of the geometry around pivot point and make that the new definition of the geometry. I do not want te keep editing the rotationZ but I want to have the current rotationZ to be the new rotationZ 0.
This way when I create a new rotation task, it will start from the new given pivot point and the newly given rad.
What I've tried, but then the rotation point moves:
// Add cube to do calculations
var box = new THREE.Box3().setFromObject( o );
var size = box.getSize();
var offsetZ = size.z / 2;
o.geometry.translate(0, -offsetZ, 0)
// Do ratation
o.rotateZ(CalcUtils.degreeToRad(degree));
o.geometry.translate(0, offsetZ, 0)
I also tried to add a Group and rotate that group and then remove the group. But I need to keep the rotation without all the extra objects. The code I created
var box = new THREE.Box3().setFromObject( o );
var size = box.size();
var geometry = new THREE.BoxGeometry( 20, 20, 20 );
var material = new THREE.MeshBasicMaterial( { color: 0xcc0000 } );
var cube = new THREE.Mesh( geometry, material );
cube.position.x = o.position.x;
cube.position.y = 0; // Height / 2
cube.position.z = -size.z / 2;
o.position.x = 0;
o.position.y = 0;
o.position.z = size.z / 2;
cube.add(o);
scene.add(cube);
// Do ratation
cube.rotateY(CalcUtils.degreeToRad(degree));
// Remove cube, and go back to single object
var position = o.getWorldPosition();
scene.add(o)
scene.remove(cube);
console.log(o);
o.position.x = position.x;
o.position.y = position.y;
o.position.z = position.z;
So my question, how do I save the current rotation as the new 0 rotation point. Make the rotation final
EDIT
I added an image of what I want to do. The object is green. I have a 0 point of the world (black). I have a 0 point of the object (red). And I have rotation point (blue).
How can I rotate the object around the blue point?
I wouldn't recommend updating the vertices, because you'll run into trouble with the normals (unless you keep them up-to-date, too). Basically, it's a lot of hassle to perform an action for which the transformation matrices were intended.
You came pretty close by translating, rotating, and un-translating, so you were on the right track. There are some built-in methods which can help make this super easy.
// obj - your object (THREE.Object3D or derived)
// point - the point of rotation (THREE.Vector3)
// axis - the axis of rotation (normalized THREE.Vector3)
// theta - radian value of rotation
// pointIsWorld - boolean indicating the point is in world coordinates (default = false)
function rotateAboutPoint(obj, point, axis, theta, pointIsWorld){
pointIsWorld = (pointIsWorld === undefined)? false : pointIsWorld;
if(pointIsWorld){
obj.parent.localToWorld(obj.position); // compensate for world coordinate
}
obj.position.sub(point); // remove the offset
obj.position.applyAxisAngle(axis, theta); // rotate the POSITION
obj.position.add(point); // re-add the offset
if(pointIsWorld){
obj.parent.worldToLocal(obj.position); // undo world coordinates compensation
}
obj.rotateOnAxis(axis, theta); // rotate the OBJECT
}
After this method completes, the rotation/position IS persisted. The next time you call the method, it will transform the object from its current state to wherever your inputs define next.
Also note the compensation for using world coordinates. This allows you to use a point in either world coordinates or local space by converting the object's position vector into the correct coordinate system. It's probably best to use it this way any time your point and object are in different coordinate systems, though your observations may differ.
As a simple solution for anyone trying to quickly change the pivot point of an object, I would recommend creating a group and adding the mesh to the group, and rotating around that.
Full example
const geometry = new THREE.BoxGeometry();
const material = new THREE.MeshBasicMaterial({ color: 0xff0000 });
const cube = new THREE.Mesh(geometry, material);
scene.add(cube)
Right now, this will just rotate around its center
cube.rotation.z = Math.PI / 4
Create a new group and add the cube
const group = new THREE.Group();
group.add(cube)
scene.add(group)
At this point we are back where we started. Now move the mesh:
cube.position.set(0.5,0.5,0)
Then move the group
group.position.set(-0.5, -0.5, 0)
Now use your group to rotate the object:
group.rotation.z = Math.PI / 4

Three.js raycasting collision not working

I am working on an arcade style Everest Flight Simulator.
In my debugger where I am building this, I have a terrain and helicopter class which generate the BufferGeometry terrain mesh, the Groups for the helipad Geometries, and the group for the helicopter Camera and Geometry.
My issue is that currently I can't seem to get any collision to detect. I imagine it may not support BufferGeometries so that is an issue for me because I need the terrain to be a Buffer since it's far too expansive... as a standard geometry it causes a memory crash in the browser.
However, testing the helipad geometries alone it still does not trigger. They are in a group so I add the groups to a global window array and set the collision check to be recursive but to no avail.
Ultimately, I am open to other forms of collision detection and may need two types as I have to use buffer geometries. Any ideas on how to fix this or a better solution?
The Helicopter Object Itself
// Rect to Simulate Helicopter
const geometry = new THREE.BoxGeometry( 2, 1, 4 ),
material = new THREE.MeshBasicMaterial(),
rect = new THREE.Mesh( geometry, material );
rect.position.x = 0;
rect.position.y = terrain.returnCameraStartPosY();
rect.position.z = 0;
rect.rotation.order = "YXZ";
rect.name = "heli";
// Link Camera and Helicopter
const heliCam = new THREE.Group(),
player = new Helicopter(heliCam, "OH-58 Kiowa", 14000);
heliCam.add(camera);
heliCam.add(rect);
heliCam.position.set( 0, 2040, -2000 );
heliCam.name = "heliCam";
scene.add(heliCam);
Adding Objects to Global Collision Array
// Add Terrain
const terrain = new Terrain.ProceduralTerrain(),
terrainObj = terrain.returnTerrainObj(),
helipadEnd = new Terrain.Helipad( 0, 1200, -3600, "Finish", true ),
helipadStart = new Terrain.Helipad( 0, 2000, -2000, "Start", false ),
helipadObjStart = helipadStart.returnHelipadObj(),
helipadObjEnd = helipadEnd.returnHelipadObj();
window.collidableMeshList.push(terrainObj);
window.collidableMeshList.push(helipadObjStart);
window.collidableMeshList.push(helipadObjEnd);
Collision Detection Function Run Every Frame
collisionDetection(){
const playerOrigin = this.heli.children[1].clone(); // Get Box Mesh from Player Group
for (let i = playerOrigin.geometry.vertices.length - 1; i >= 0; i--) {
const localVertex = playerOrigin.geometry.vertices[i].clone(),
globalVertex = localVertex.applyMatrix4( playerOrigin.matrix ),
directionVector = globalVertex.sub( playerOrigin.position ),
ray = new THREE.Raycaster( playerOrigin, directionVector.clone().normalize() ),
collisionResults = ray.intersectObjects( window.collidableMeshList, true ); // Recursive Boolean for children
if ( collisionResults.length > 0 ){
this.landed = true;
console.log("Collision");
}
// if ( collisionResults.length > 0 && collisionResults[0].distance < directionVector.length() ){
// this.landed = true;
// console.log("Collision with vectorLength")
// }
}
}
It's hard to tell what's going on inside your custom classes, but it looks like you're using an Object3D as the first argument of the raycaster, instead of a Vector3 when you use this.heli.children[1].clone(). Why don't you try something like:
var raycaster = new THREE.Raycaster();
var origin = this.heli.children[1].position;
raycaster.set(origin, direction);
Also, are you sure you're using a BufferGeometry? Because when you access a vertex value like this: playerOrigin.geometry.vertices[i], it should give you an error. There is no vertices attribute in a BufferGeometry so I don't know how you're determining the direction vector.

what's wrong with it - or how to find correct THREE.PerspectiveCamera settings

I have a simple THREE.Scene where the main content is a THREE.Line mesh that visualizes the keyframe based path that the camera will follow for some scripted animation. There is then one THREE.SphereGeometry based mesh that is always repositioned to the current camera location.
The currently WRONG result looks like this (the fractal background is rendered independently but using the same keyframe input - and ultimately the idea is that the "camera path" visualization ends up in the same scale/projection as the respective fractal background...):
The base is an array of keyframes, each of which represents the modelViewMatrix for a specific camera position/orientation and is directly used to drive the vertexshader for the background, e.g.:
varying vec3 eye, dir;
void main() {
gl_Position = vec4(position, 1.0);
eye = vec3(modelViewMatrix[3]);
dir = vec3(modelViewMatrix * vec4(position.x , position.y , 1, 0));
}
(it is my understanding that "eye" is basically the camera position while "dir" reflects the orientation of the camera and by the way it is used during the ray marching implicitly leads to a perspective projection)
The respective mesh objects are created like this:
visualizeCameraPath: function(scene) {
// debug: visualize the camera path
var n= this.getNumberOfKeyFrames();
var material = new THREE.LineBasicMaterial({
color: 0xffffff
});
var geometry = new THREE.Geometry();
for (var i= 0; i<n; i++) {
var m= this.getKeyFrameMatrix(true, i);
var pos= new THREE.Vector3();
var q= new THREE.Quaternion();
var scale= new THREE.Vector3();
m.decompose(pos,q,scale);
geometry.vertices.push( new THREE.Vector3( pos.x, pos.y, pos.z ));
}
this.camPath = new THREE.Line( geometry, material );
this.camPath.frustumCulled = false; // Avoid getting clipped - does not seem to help one little bit
scene.add( this.camPath );
var radius= 0.04;
var g = new THREE.SphereGeometry(radius, 10, 10, 0, Math.PI * 2, 0, Math.PI * 2);
this.marker = new THREE.Mesh(g, new THREE.MeshNormalMaterial());
scene.add(this.marker);
}
in order to play the animation I update the camera and the marker position like this (I guess it is already wrong how I use the input matrix "m" directly on the "shadowCamera" - eventhough I think that it contains the correct position):
syncShadowCamera(m) {
var pos= new THREE.Vector3();
var q= new THREE.Quaternion();
var scale= new THREE.Vector3();
m.decompose(pos,q,scale);
this.applyMatrix(m, this.shadowCamera); // also sets camera position to "pos"
// highlight current camera-position on the camera-path-line
if (this.marker != null) this.marker.position.set(pos.x, pos.y, pos.z);
},
applyMatrix: function(m, targetObj3d) {
var pos= new THREE.Vector3();
var q= new THREE.Quaternion();
var scale= new THREE.Vector3();
m.decompose(pos,q,scale);
targetObj3d.position.set(pos.x, pos.y, pos.z);
targetObj3d.quaternion.set(q.x, q.y, q.z, q.w);
targetObj3d.scale= scale;
targetObj3d.updateMatrix(); // this.matrix.compose( this.position, this.quaternion, this.scale );
targetObj3d.updateMatrixWorld(true);
},
I've tried multiple things with regard to the camera and the screenshot reflects the output with disabled "this.projectionMatrix" (see below code).
createShadowCamera: function() {
var speed = 0.00039507;
var z_near = Math.abs(speed);
var z_far = speed * 65535.0;
var fH = Math.tan( this.FOV_Y * Math.PI / 360.0 ) * z_near;
var fW = Math.tan( this.FOV_X * Math.PI / 360.0 ) * z_near;
// orig opengl used: glFrustum(-fW, fW, -fH, fH, z_near, z_far);
var camera= new THREE.PerspectiveCamera();
camera.updateProjectionMatrix = function() {
// this.projectionMatrix.makePerspective( -fW, fW, fH, -fH, z_near, z_far );
this.projectionMatrix= new THREE.Matrix4(); // hack: fallback to no projection
};
camera.updateProjectionMatrix();
return camera;
},
My initial attempt had been to use the same kind of settings that the opengl shader for the fractal background had been using (see glFrustum above). Unfortunately it seems that I have yet managed to correctly map the input "modelViewMatrix" (and the projection implicitly performed by the raymarching in the shader) to equivalent THREE.PerspectiveCamera settings (orientation/projectionMatrix).
Is there any matrix calculation expert here, that knows how to obtain the correct transformations?
Finally I have found one hack that works.
Actually the problem was made up of two parts:
1) Row- vs column-major order of modelViewMatrix: The order expected by the vertex shader is the oposite of what the remaining THREE.js expects..
2) Object3D-hierarchy: i.e. Scene, Mesh, Geometry, Line vertices + Camera: where to put the modelViewMatrix data so that it creates the desired result (i.e. the same result that the old bloody opengl application produced): I am not happy with the hack that I found here - but so far it is the only one that seems to work:
I DO NOT touch the Camera.. it stays at 0/0/0
I directly move all the vertices of my "line"-Geometry relative to the real camera position (see "position" from the modelViewMatrix)
I then disable "matrixAutoUpdate" on the Mesh that contains my "line" Geometry and copy the modelViewMatrix (in which I first zeroed out the "position") into the "matrix" field.
BINGO.. then it works. (All of my attempts to achieve the same result by rotating/displacing the Camera or by displacing/rotating any of the Object3Ds involved have failed miserably..)
EDIT: I found a better way than updating the vertices and at least keeping all the manipulations on the Mesh level (I am still moving the world around - like the old OpenGL app would have done..). To get the right sequence of translation/rotation one can also use ("m" is still the original OpenGL modelViewMatrix - with 0/0/0 position info):
var t= new THREE.Matrix4().makeTranslation(-cameraPos.x, -cameraPos.y, -cameraPos.z);
t.premultiply ( m );
obj3d.matrixAutoUpdate=false;
obj3d.matrix.copy(t);
If somebody knows a better way that also works (one where the Camera is updated without having to directly manipulate object matrices) I'd certainly be interested to hear it.

Fit to screen from different Orthographic camera positions

Made a simple jsFiddle example to illustrate a problem.
I'm trying to fit object's bounding box to screen from different camera positions. In example in dat.GUI panel you can change camera position and then click button fit to screen.
When changing y and z (positive) camera positions to find camera's top and bottom properties code below is used
var top = boundingBox.max.y * Math.cos(angleToZAxis) + boundingBox.max.z * Math.sin(angleToZAxis); // line 68
var bottom boundingBox.min.y * Math.cos(angleToZAxis) + boundingBox.min.z * Math.sin(angleToZAxis);
I would like to know how I can include camera's x position and negative positions in this calculation, what is the math behind this. Should I use rotation matrix and how to use it?
Or maybe it can be achieved in some simple way with threejs methods, can't figure out, tried the code below but something is wrong:
var matrix = new THREE.Matrix4();
matrix.lookAt ( this.camera.position, new THREE.Vector3(0, 0, 0), new THREE.Vector3(0, 1, 0) );
var bbMax = boundingBox.max.clone().applyMatrix4(matrix);
var bbMin = boundingBox.min.clone().applyMatrix4(matrix)
;
to fit an orthographic camera you have to simply change its zoom and position
you can calculate zoom from the bounding box of your object
(I used the boxes from geometry, but you will have to take in account matrices of the objects in group; I used them because .setFromObject was not returning consistent value)
Canvas3D.prototype.fitToScreen = function() {
this.group.children[0].geometry.computeBoundingBox();
var boundingBox = this.group.children[0].geometry.boundingBox.clone();
this.group.children[1].geometry.computeBoundingBox();
boundingBox.union(this.group.children[1].geometry.boundingBox);
var rotation = new THREE.Matrix4().extractRotation(this.camera.matrix);
boundingBox.applyMatrix4(rotation);
this.camera.zoom = Math.min(this.winWidth / (boundingBox.max.x - boundingBox.min.x),
this.winHeight / (boundingBox.max.y - boundingBox.min.y)) * 0.95;
this.camera.position.copy(boundingBox.center());
this.camera.updateProjectionMatrix();
this.camera.updateMatrix();
};
using this will not work in your fiddle because you are using OrbitControls and they rotate camera on update based on their own state - so either update that state or create your own controls
also either move camera back after
this.camera.position.copy(boundingBox.center());
or set near plane to -1000 to avoid having cut object
this.camera = new THREE.OrthographicCamera(this.winWidth / -2,
this.winWidth / 2 , this.winHeight / 2, this.winHeight / -2, -10000, 10000);
EDIT
now i see that you dont want to just fit the object but the whole box...
to do so an easy way is to project the points of the box and get the distances of extremes in pixels, then you can set ortho camera directly
boundingBox = new THREE.Box3().setFromObject(this.group);
//take all 8 vertices of the box and project them
var p1 = new THREE.Vector3(boundingBox.min.x,boundingBox.min.y,boundingBox.min.z).project(this.camera);
var p2 = new THREE.Vector3(boundingBox.min.x,boundingBox.min.y,boundingBox.max.z).project(this.camera);
var p3 = new THREE.Vector3(boundingBox.min.x,boundingBox.max.y,boundingBox.min.z).project(this.camera);
var p4 = new THREE.Vector3(boundingBox.min.x,boundingBox.max.y,boundingBox.max.z).project(this.camera);
var p5 = new THREE.Vector3(boundingBox.max.x,boundingBox.min.y,boundingBox.min.z).project(this.camera);
var p6 = new THREE.Vector3(boundingBox.max.x,boundingBox.min.y,boundingBox.max.z).project(this.camera);
var p7 = new THREE.Vector3(boundingBox.max.x,boundingBox.max.y,boundingBox.min.z).project(this.camera);
var p8 = new THREE.Vector3(boundingBox.max.x,boundingBox.max.y,boundingBox.max.z).project(this.camera);
//fill a box to get the extremes of the 8 points
var box = new THREE.Box3();
box.expandByPoint(p1);
box.expandByPoint(p2);
box.expandByPoint(p3);
box.expandByPoint(p4);
box.expandByPoint(p5);
box.expandByPoint(p6);
box.expandByPoint(p7);
box.expandByPoint(p8);
//take absolute value because the points already have the correct sign
var top = box.max.y * Math.abs(this.camera.top);
var bottom = box.min.y * Math.abs(this.camera.bottom);
var right = box.max.x * Math.abs(this.camera.right);
var left = box.min.x * Math.abs(this.camera.left);
this.updateCamera(left, right, top, bottom);
this code also stretches the view to fit exactly into the window so you will have to check for the aspect ratio and change one size accordingly, but that should be trivial

How to get other 3D objects within a radius of a position in three.js

I have a 3D scene in three.js in which I need to get an array of objects that are within X range of a source object. At the moment, the example I'm using is utilizing raycasting inside of a for loop that iterates an array of "collidable objects" that exist in the scene. I feel like there must be a better way to handle this because this approach is exponentially more complex if every object in the array has to raycast from itself to every other object in the array. This has massive performance impacts as the array of collidable objects grows.
//hold collidable objects
var collidableObjects = [];
var scene = new THREE.Scene();
var cubeGeo = new THREE.CubeGeometry( 10 , 10 , 10 );
var materialA = new THREE.MeshBasicMaterial( { color: 0xff0000 } );
var materialB = new THREE.MeshBasicMaterial( { color: 0x00ff00 } );
var cubeA = new THREE.Mesh( cubeGeo , materialA );
collidableObjects.push( cubeA );
scene.add( cubeA );
//Change this variable to a larger number to see the processing time explode
var range = 100;
for( var x = 0 ; x < range ; x += 20 ) {
for( var z = 0; z < range ; z += 20 ) {
if( x === 0 && z === 0 ) continue;
var cube = new THREE.Mesh( cubeGeo , materialB );
scene.add( cube );
cube.position.x = x;
cube.position.z = z;
collidableObjects.push( cube );
var cube = cube.clone();
scene.add( cube );
cube.position.x = x * -1;
cube.position.z = z;
collidableObjects.push( cube );
var cube = cube.clone();
scene.add( cube );
cube.position.x = x;
cube.position.z = z * -1;
collidableObjects.push( cube );
var cube = cube.clone();
scene.add( cube );
cube.position.x = x * -1;
cube.position.z = z * -1;
collidableObjects.push( cube );
}
}
var camera = new THREE.PerspectiveCamera( 75, window.innerWidth / window.innerHeight, 0.1, 1000 );
var renderer = new THREE.WebGLRenderer();
renderer.setSize( window.innerWidth, window.innerHeight );
document.body.appendChild( renderer.domElement );
camera.position.y = 200;
camera.lookAt( scene.position );
function render() {
//requestAnimationFrame(render);
renderer.render(scene, camera);
console.log( getObjectsWithinRange( cubeA , 30 ) );
}
function getObjectsWithinRange( source , range ) {
var startTime = new Date().getTime();
var inRange = [];
for( var i = 0; i < collidableObjects.length ; ++i ) {
var ray = new THREE.Raycaster( source.position , collidableObjects[i].position , 0 , range );
if( ( obj = ray.intersectObject( collidableObjects[i] ) ) && obj.length ) {
inRange.push( obj[0] );
}
}
var endTime = new Date().getTime();
console.log( 'Processing Time: ' , endTime - startTime );
return inRange;
}
render();
You can see the JSfiddle of this here.
If you change the indicated variable to a larger number say 200, then you'll see the processing time start to get out of control. I feel like there has to be a simpler way to reduce down the array of doing this so I looked at the documentation for the Raycaster of three.js and I noticed that both the near and far attributes say "This value indicates which objects can be discarded based on the distance." so I presume there's some internal function that is used to refine the results down based on distance before casting all the rays.
I did a little digging on this and came up with a single function inside of Ray.js.
distanceToPoint: function () {
var v1 = new THREE.Vector3();
return function ( point ) {
var directionDistance = v1.subVectors( point, this.origin ).dot( this.direction );
// point behind the ray
if ( directionDistance < 0 ) {
return this.origin.distanceTo( point );
}
v1.copy( this.direction ).multiplyScalar( directionDistance ).add( this.origin );
return v1.distanceTo( point );
};
}(),
I guess what I'm looking for is a better way to get all of the objects in the scene that are within X radius of a source object. I don't even need to use the Raycasting because I'm not interested in mesh collision, rather just a list of the objects within X radius of the source object. I don't even need to recurse into the children of those objects because of the way the scene is set up. So I feel like there must be some internal function or something that simply uses the THREE.Vector3 objects and math to refine them by distance. That has to be a lot cheaper math to run than Raycasting in this case. If there's already a function that handles this somewhere in three.js, I don't want to recreate one from scratch. I also realize this may be a very long-winded question for what could very well be a single line answer, but I wanted to make sure I have all the details and whatnot here in case someone else looking to do this searches for it later.
Collision checking is a more general problem and I think you'll have more success if you think about it in a context outside of Three.js. There are a number of methods for managing large numbers of objects that need to check for collision with each other. Here are a few optimizations that might be relevant to you here:
The first optimization is for each object to have a boolean property indicating whether it moved since the last physics update. If both objects you're comparing haven't moved, you don't need to recalculate collision. This is mostly relevant if you have a large number of objects in a steady state (like crates you can push around). There are a number of other optimizations you can build on top of this; for example, often if two objects haven't moved, they won't be colliding, because if they were colliding they would be recoiling (moving apart).
The second optimization is that you usually only need to check collision within a certain distance. For example, if you know that all of your objects are smaller than 100 units, then you can just check whether (x1-x2)^2 + (y1-y2)^2 + (z1-z2)^2 > 100^2. If the check is true (indicating the distance between the two objects is large) then you don't need to calculate detailed collisions. In fact this is more or less the near/far optimization that Raycaster provides for you, but you are not making use of it in your code, since you are always calling the intersectObject method.
The third optimization is that you are allocating a bunch of new Raycaster and related objects in every physics update. Instead, you can keep a pool of Raycasters (or even a single Raycaster) and just update their properties. This will avoid a lot of garbage collecting.
Finally, the most common generalized approach to dealing with a large number of collideable objects is called spatial partitioning. The idea is basically that you divide your world into a given number of spaces and keep track of which space objects are in. Then, when you need to calculate collision, you only need to check other objects that are in the same space. The most common approach for doing this is to use an Octree (an 8-ary tree). As WestLangley mentioned, Three.js has an Octree implementation starting in r59, along with an example (source). Here is a reasonable introduction to the concept of spatial partitioning using 2D examples.
Outside of these optimizations, if you need to do anything particularly complicated, you may want to consider using an external physics library, which will manage optimizations like these for you. The most popular ones for use with Three.js at the moment are Physijs, Cannon.js, and Ammo.js.

Resources