c# - Delete 3D Element from ObservableCollection -

in wpf 4.0 project, have observablecollection contain selected visual3d view :

public observablecollection<visual3d> selectedelements         {             { return _selectedelements; }             set             {                 if (equals(_selectedelements, value))                 {                     return;                 }                  _selectedelements = value;                 raisepropertychanged(() => selectedelements);             }         } 

visual3d elements selected clicking , source-code in vm :

public hittestresultbehavior hittestdown(hittestresult result)         {             var resultmesh = result raymeshgeometry3dhittestresult;              if (resultmesh == null)                 return hittestresultbehavior.continue;              // obtain clicked modelvisual3d.             var vis = resultmesh.visualhit modelvisual3d;               if (vis != null)             {                 type vistype = vis.gettype();                 if (vistype.name == "truncatedconevisual3d" || vistype.name == "boxvisual3d")                 {                     var geomodel = resultmesh.modelhit geometrymodel3d;                     if (geomodel != null)                     {                         var selectemat = geomodel.material diffusematerial;                         if (selectemat != null) selectemat.brush.opacity = selectemat.brush.opacity <= 0.7 ? 1 : 0.7;                     }                      // otherwise it's chair. transform3dgroup.                     var xformgrp = vis.transform transform3dgroup;                      // should not happen, play safe anyway.                     if (xformgrp == null)                     {                         return hittestresultbehavior.stop;                     }                       // loop through child tranforms.                     foreach (transform3d t in xformgrp.children)                     {                         // find translatetransform3d.                         var trans =                             t translatetransform3d;                          if (trans != null)                         {                             // define animation transform.                             var anima = new doubleanimation();                             if (trans.offsety == 0)                             {                                 dependencyproperty prop = translatetransform3d.offsetzproperty;                                  if (math.abs(trans.offsetz) < 2)                                 {                                     anima.to = 20.5*math.sign(trans.offsetz);                                     debug.assert(selectedelements != null, "selectedelements != null");                                 }                                  else                                 {                                     anima.to = 1*math.sign(trans.offsetz);                                     selectedelements.add(vis);                                  }                                  // start animation , stop hit-testing.                                 trans.beginanimation(prop, anima);                                 return hittestresultbehavior.stop;                             }                         }                     }                 }             }              return (hittestresultbehavior) hittestfilterbehavior.continue;         } 

and want delete 1 or visual3d element thank in advance

i have implemented methode it's not work :

private void unloadproduct()     {         if (canunload)         {             foreach (visual3d selectedelement in selectedelements)             {                 if (selectedelement.dependencyobjecttype.name == "truncatedconevisual3d")                 {                     var test = (truncatedconevisual3d) selectedelement;                     int id = test.visualid;                     elementscollection.removeat(id);                     raisepropertychanged(() => elementscollection);                 }                 else                 {                     var test = (boxvisual3d) selectedelement;                     int id = test.visualid;                     productscollection.removeat(id);                 }             }         }     }