javascript - Experiencing something odd when using THREE.Raycaster for collision detection (r68) -

i've been using three.raycaster test collisions many things in game engine far, it's great , works well.

however, i've run quite peculiar cannot seem figure out. point of view, logic , code sound expected result not correct. perhaps i'm missing obvious thought i'd ask help.

i casting rays out center of top of group of meshes, 1 one, in circular arc. meshes children of parent object3d , goal test collisions between origin mesh , other meshes children of parent. test rays, using three.arrowhelper.

here's image of result of code - http://imgur.com/ipzyusa

in image, arrowhelper objects positioned (origin:direction) how want them. yeah, there's wrong picture, code produces is:

var degree = math.pi / 16,     tiles = this.tilescontainer.children,     tilesnum = tiles.length,     raycaster = new three.raycaster(),     raydirections, raydirectionsnum, rayorigin, raydirection, collisions,     tile, i, j, k;  (i = 0; < tilesnum; i++) {     tile = tiles[i];     rayorigin = new three.vector3(         tile.position.x,         tile.geometry.boundingbox.max.y,         tile.position.z     );     raydirections = [];      (j = 0; j < math.pi * 2; j += degree) {         raydirections.push(new three.vector3(math.sin(j), 0, math.cos(j)).normalize());     }      raydirectionsnum = raydirections.length;      (k = 0; k < raydirectionsnum; k++) {         raydirection = raydirections[k];          raycaster.set(rayorigin, raydirection);          collisions = raycaster.intersectobjects(tiles);          this.testray(rayorigin, raydirection, collisions);     } } 

the testray method looks this:

testray: function (origin, direction, collisions) {     var arrowhelper = new three.arrowhelper(         direction,         origin,         1,         (collisions.length === 0) ? 0xff0000 : 0x0000ff     );      this.scene.add(arrowhelper); } 

now, obviously, off image. rays collide other meshes should blue, while not collide should red. it's clear image totally out of whack, , when inspect collisions, off results. lot of rays appear blue in image, i'm getting huge number of collisions, 30 collisions single ray sometimes, nothing others when right next other tiles.

i can't figure out might be. how can many rays should blue red? , how can rays tiles @ edge of level have blue collisions tiles not exist?

really scratching head (read: bashing head repeatedly) on one, super appreciated!

the solution outside code , not, @ least don't believe, related outdated r68 build.

when making tile meshes, needed set three properties on them

tilemesh.matrixautoupdate = false; tilemesh.updatematrix(); tilemesh.updatematrixworld(); // new 

i doing first two, not last one. why necessary, not know, seems little odd me fixed problem. had axishelper in scene, if @ original image, you'll notice arrowhelper objects blue pointing towards axishelper. weird because axishelper added scene, not tilescontainer. adding arrowhelper objects tilescontainer did not help.

the process render scene had raycaster code run before axishelper added scene , before initial render happened. problem fixed if moved raycaster code call after axishelper added, hacky solution.

so true fix add .updatematrixworld() tiles. result looks http://imgur.com/8lewqxl, correct (the arrowhelper objects have been shortened in length don't overlap).

big manthrax on one.