Superimposing 3D Histograms via GLISO Option && Making Them Transparent

Dear ROOTers;

I would like to superimpose two 3D histograms that are in the shape of two solids in my detector geometry for visualization purposes. I would like to use the draw option (“GLISO”) so that I could navigate, zoom in or zoom out in an interactive OpenGL viewer session. As I run the code attached, it looks like even though I drew two histograms on the same canvas, I could only rotate one of them and the other one fades away and looks frozen out. I was wondering how I could achieve the superposition completely.

And also assuming I have two solids(histograms) surrounding/intersecting with each other, how can I superimpose them via iso surface option by making them transparent so that I could see both of them at the same?

PS 1: I attached the macro and also the input file that macro uses.
PS 2: I tried TGLTH3Composition as well but iso surface drawing was not possible.

Thank you very much for your help,
CaseL_PostTDR_3D.root (73.6 KB)
geometry_ROOT.C (1.01 KB)

Just to make my code snippet more visible…

void geometry_ROOT(){

    // General settings
    // For OpenGL
    // Open the file
    TFile *file = new TFile("CaseL_PostTDR_3D.root","READ");
    //Get Histograms
    TH3F *h1 = (TH3F*)file->Get("h_x_12");
    TH3F *h2 = (TH3F*)file->Get("h_x_5");

    // Color Settings

    //Create a canvas
    TCanvas *c1 = new TCanvas ("c1", "", 1000, 800);


Your histograms are real histogram data of you use them to Draw volumes ?
If so I guess you better use the TGeo package.