Project geometry using TEveProjectionManager

I’m having trouble projecting a (square) tpc geometry using TEveProjectionManager.
From what I gaver looking at the examples from Alice you can only project “simple” geometry. i.e their so called ESD files. I tried projecting my geometry which is build with a TGeomanager with nodes and volumes but it does not work.
Should one somehow convert the TGeomanager to TEveGeoShape, save as root and extract the “shapes” from the rootfile? Basically how did Alice create their ESD file?
Thanks very much,

Hi Sebastien,

Yes, you can not project TGeo geometries directly. TEveGeoShapes need to be created.

You can extract geo-shapes from gGeo manager though: … ot=AliRoot

For ALICE the extract was created by using TEveGeoTopNode initialized from gGeoManager, then you expand the tree as much as you need it (you can also use ExpandIntoListTrees()), mark entries that you want exported (draw on/off) and then call SaveExtract() on the top node.

The nodes were hand-picked to present a reasonable outline for event-data. I think now they even use different extracts for 3D, r-phi and rho-z.

To view the extract, there is show_extract.C and projection.C in tutorials/eve/.

This is a bit of a black art … sorry about this.


Ok thanks very much. Yes SaveExtract() on the top node works fine.