Add support of TPolyMarker3D on TCanvas with geom

Author: linev

scripts/JSRoot.geom.js

@@ -3259,13 +3259,13 @@ JSROOT.define(['d3', 'three', 'geobase', 'painter', 'base3d'], (d3, THREE, geo,
             let dom = this.createScene(size.width, size.height);
 
             this.add3dCanvas(size, dom, this._webgl);
-
-            // set top painter only when first child exists
-            this.setAsMainPainter();
          }
       }
 
       return promise.then(() => {
+         // set top painter only when first child exists
+         this.setAsMainPainter();
+
          this.createToolbar();
 
          if (this._clones)

scripts/JSRoot.hist3d.js

@@ -3374,10 +3374,18 @@ JSROOT.define(['d3', 'painter', 'base3d', 'latex', 'hist'], (d3, jsrp, THREE, lt
 
       let fp = this.getFramePainter();
 
-      if (!fp || !fp.mode3d || !fp.toplevel)
+      let step = 1, sizelimit = 50000, numselect = 0, poly = this.getObject();
+
+
+      if (!fp || !fp.mode3d)
          return Promise.reject(Error("Fail to draw poly markers without 3D mode"));
 
-      let step = 1, sizelimit = 50000, numselect = 0, poly = this.getObject();
+      if (!fp.toplevel) {
+         let main = this.getMainPainter();
+         if (main && typeof main.drawExtras == 'function')
+            return main.drawExtras(poly);
+         return Promise.resolve(this);
+      }
 
       for (let i = 0; i < poly.fP.length; i += 3) {
          if ((poly.fP[i] < fp.scale_xmin) || (poly.fP[i] > fp.scale_xmax) ||