Generic Trapezoid Twisted along z-Axis

A generic trapezoid twisted along z-axis can be constructed using C++ or some simple text:

:volu twistedTrap TWISTEDTRAP
 30*degree // angle twisted around z
 60 // dz/2: half height in z [mm]
 20*degree // theta
 5*degree // phi
 40 // dy1/2: half y @ -dz/2 [mm]
 30 // half x @ -dz/2 and -dy1/2 [mm]
 40 // half x @ -dz/2 and +dy1/2 [mm]
 16 // dy1/2: half y @ dz/2 [mm]
 10 // half x @ dz/2 and -dy1/2 [mm]
 14 // half x @ dz/2 and +dy1/2 [mm]
 10*degree // angle with respect to y from the centre of the side
 G4_WATER // material

NOTE!

• The default unit of the twist angle here is rad, not degree. We need to explicitly multiply the number with degree if we want to use degree as the unit. This is different from untwisted shapes, where the default unit of an angle is already degree.
• The twist must be within ±(0, 90) degree (not including 0 and 90 degrees).

The full source code is in trap.tg, which can be visualized using the macro file trap.mac, assuming an universal Geant4 application, such as MinGLE or GEARS, is available:

git clone https://github.com/jintonic/geant4
cd geant4/detector/CSG/twisted
# generate animated picture, trap.gif
./twist.sh
# or launch a UI
gears
# in the UI, run
/control/execute trap.mac