|Message: Coordinates transformation in the G4NormalNavigation||Not Logged In (login)|
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I have a question on the G4NormalNavigation about the transformation of points.
In the G4NormalNavigation::LevelLocate() method, a Point for Daugther volume is calculated using
samplePoint = history.GetTopTransform().TransformPoint(globalPoint);
But I think it should be transform from a localPoint inside its mother LV using its transformation:
samplePoint = history.GetTopTransform().TransformPoint(localPoint);
Another question is that, in the G4NormalNavigation::ComputeSafety() method, a Point for Dauther volume is calculated using
G4AffineTransform sampleTf(samplePhysical->GetRotation(), samplePhysical->GetTranslation()); sampleTf.Invert(); const G4ThreeVector samplePoint = sampleTf.TransformPoint(localPoint);
why we need to INVERT this transformation?
Actually I am not understanding the geometry transformation mechanism in Geant4 very well. I am expecting patient answers for me. Thanks a lot!
Best regards, Yuefeng