// 3D points array.

var points=[];

​

var Vector=function(x,y,z) {

  this.x=x;

  this.y=y;

  this.z=z;

};

​

Vector.prototype.toString= function() {

  return (' x: ' + this.x + ' y: ' + this.y  + ' z : ' + this.z);

};

​

// returns a new vector translatedfrom ampVec * random 

Vector.prototype.createRandomShift= function(ampVec) {

    var thisRandom = Math.random()*0.9+0.1;

  return  new Vector(

  thisRandom*ampVec.x+this.x,

   thisRandom*ampVec.y+this.y,

    thisRandom*ampVec.z+this.z    );

};

​

var pointCount=20;

​

var pt = new Vector(Math.random()*100|0, Math.random()*100|0, Math.random()*100|0 );

var ampVec = new Vector(Math.random()*4-2, Math.random()*4-2, Math.random()*4 - 2);

var ampVecAmp = new Vector(Math.random()*2-1, Math.random()*2-1, Math.random()*2-1) ;

​

// fill the point array.

// based on the current point shifted randomly by ampVec

// ampVec itself is shifted randomly by ampVecAmp 

for(var i=0; i<pointCount; i++) {

  points.push(pt );

  pt=pt.createRandomShift(ampVec);

  ampVec=ampVec.createRandomShift(ampVecAmp);

}

​

// array of face. a face is an array of 3 point indexes.

var facelist=[];

​

var faceCount=10, i=faceCount;

​

// fill the face array

while(i--) {

  var thisFacePoints=[];

  var ip1 = 0;

  // 3 point indexes

  thisFacePoints.push(ip1=Math.random()*pointCount|0);

  thisFacePoints.push(Math.random()*pointCount|0);

  thisFacePoints.push(Math.random()*pointCount|0);

    facelist.push(thisFacePoints);

}

​

// returns the min z for a face

var minZ=function(f) {

  return Math.min(f[0].z, Math.min(f[1].z, f[2].z));

};

// returns the max z for a face                  

var maxZ=function(f) {

  return Math.max(f[0].z, Math.max(f[1].z, f[2].z));

};

// !!! sort the faces on Z !!!

facelist.sort(function(a,b) {

  if (maxZ(a) < minZ (b)) return 1;  // a fully below b

  if (minZ(b) < minZ(a) ) return -1;  // b fully below a

  // !!!!!!!!!!!!!!!!!!!!!!!!

  // in fact here is the tricky part :

  // here a and b overlap in Z.

  return trickyFaceZSort(a,b); 

 });

​

// !!!!!! returns wether face a is < to face b when looking at Z (0,0,1).

//Required : a and b overlaps by Z.

var trickyFaceZSort= function(a,b) {

  // do some checks on projected(xi), projected(yi)  -> return 0 if no overlap

  // then you have the hardest part ahead : x,y and z overlap.

  return 0;

};

​

// Print sorted faces

for(var i=0; i<facelist.length; i++) {

  var fp=facelist[i];

   console.log(' *** face ' + i + ' *** ');

   console.log(' ** point 0 ' + points[fp[0]] + ' *** ');

   console.log(' ** point 1 ' + points[fp[1]] + ' *** ');

   console.log(' ** point 2 ' + points[fp[2]] + ' *** ');  

}

​

​

​