I am new to root, and have been trying to use the 3-d drawing classes.
Does anybody have a simple example of ray-tracing through a target?
Is there a tutorial or set of examples anywhere? The Root User's Guide
has none, and the examples in $ROOTSYS/tutorials are not very complete.
I have several puzzles:
1) I don't understand what coordinates are being used. For instance,
when I change the {dx,dy,dz} in a TBRIK constructor the picture
does not change. It looks like there is some sort of automatic
scaling going on (this TBRIK is the only object). I guess I'll
just draw an invisible TBRIK object enclosing the entire system.
2) The TBRIK object does not seem to fill itself. I tried many
variations on SetFillColor() and SetFillStyle(). None worked.
3) I cannot figure out how to get TPolyLine3D to display its line.
This could be related to (1) and the coordinates are simply off
the screen. Using a thin and narrow TBRIK for each ray is difficult,
as I need to figure out how to rotate them....
4) the TNode-s seem to automatically link themselves together in
a list. The use of TNode::cd() is rather puzzling. Anybody know
what is going on?
5) TGeometry seems to be related to this, but shapes.C does not use
one, and the nodes (or shapes ?) seem to be linked into the canvas?
Below is my test script, based upon tutorials/shapes.C. The TBRIK
object displays its lines, and I can rotate it using the mouse,
but it is not filled.
Any help or pointers would be appreciated.
Tom Roberts tjrob@fnal.gov
{
c1 = new TCanvas("c1","Test Ray-Tracing",800,600);
c1->SetFillColor(10);
TBRIK *tgt = new TBRIK("Target","Target","void",150,150,150);
tgt->SetLineColor(1);
tgt->SetFillColor(2);
tgt->SetFillStyle(1001);
// Build the geometry hierarchy
node1 = new TNode("NODE1","NODE1",tgt);
node1->cd();
// Draw this geometry in the current canvas
node1->cd();
node1->Draw();
c1->Update();
}
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