Fix - transparancy handling in geo painter

According to this article:

http://stackoverflow.com/questions/15994944/

We should specify mesh.renderOrder attribute to help renderer.
Otherwise it tries to identify render order via distance, 
which is totally wrong.

Author: linev

changes.md

@@ -3,6 +3,7 @@
 ## Changes in 5.1.x
 1. Fix - support newest TFormula in TF1 (#127)
 2. Fix - ignore NaN value in saved TF1 buffer
+3. Fix - correctly treat transparancy in geo painter
 
 
 ## Changes in 5.1.1

scripts/JSRootGeoBase.js

@@ -2910,6 +2910,7 @@
    JSROOT.GEO.ClonedNodes = function(obj, clones) {
       this.toplevel = true; // indicate if object creates top-level structure with Nodes and Volumes folder
       this.name_prefix = ""; // name prefix used for nodes names
+      this.maxdepth = 1; // maximal hierarchy depth, required for transparancy
 
       if (obj) {
          if (obj.$geoh) this.toplevel = false;
@@ -2970,6 +2971,7 @@
 
        obj._refid = this.origin.length;
        this.origin.push(obj);
+       if (sublevel>this.maxdepth) this.maxdepth = sublevel; 
 
        var chlds = null;
        if (kind===0)

scripts/JSRootGeoPainter.js

@@ -1179,6 +1179,7 @@
 
             // keep full stack of nodes
             mesh.stack = entry.stack;
+            mesh.renderOrder = this._clones.maxdepth - entry.stack.length; // order of transparancy handling
 
             obj3d.add(mesh);