a. To see a pre-prepared example, start this example in interactive mode (i.e., without any command line arguments). Just type
```
     /vis/viewer/interpolate viewfiles/movie-1
```
If you want to see an electromagnetic shower
```
     /run/beamOn
     /vis/viewer/interpolate viewfiles/movie-1
```
b. To make your own movie, save a sequence of views with
```
     /vis/viewer/save
```
Then "fly through" with
```
     /vis/viewer/interpolate".
```
The procedure is: choose a view, save, choose another view, save, and so on until you have, say, 10 saved views. Then you may
```
     /vis/viewer/interpolate
```
Note: This saves views to your current working directory. It is always good to remove any pre-existing saved files:
```
     rm *.g4view
```
or save them, e.g.
```
     mkdir views
     mv *.g4view views
```
which can subsequently be interpolated with
```
     /vis/viewer/interpolate views
```
c. Then you have a choice of how to export the movie - see 3 below.

You can use time-slicing to see particles progress through time

a. To see a pre-prepared example

  /vis/modeling/trajectories/drawByCharge-0/default/setTimeSliceInterval 0.01 ns
  /run/beamOn
  /vis/viewer/interpolate viewfiles/movie-2

b. To make your own movie

  /vis/scene/add/trajectories rich
  /vis/modeling/trajectories/drawByCharge-0/default/setTimeSliceInterval 0.01 ns
  # Optionally add features (see guidance on /vis/viewer/set/timeWindow/)
  /vis/viewer/set/timeWindow/displayLightFront true 0 0 -20 cm -0.01 ns
  /vis/viewer/set/timeWindow/displayHeadTime true
  /vis/viewer/set/timeWindow/fadeFactor 1
  /run/beamOn
  # Then set a time window and save
  /vis/viewer/set/timeWindow/startTime 0 ns .1 ns
  /vis/viewer/save
  # Then zoom, pan etc to a view of interest
  # Then set the next time window and save
  /vis/viewer/set/timeWindow/startTime .5 ns .1 ns
  /vis/viewer/save
  # Then zoom, pan etc to a view of interest
  # Then set the next time window and save
  /vis/viewer/set/timeWindow/startTime 1 ns .1 ns
  /vis/viewer/save
  # Then another view, the next time window, and a save...
  # ...repeat a few more times
  # Then try
  /vis/viewer/interpolate

How to export images using /vis/viewer/interpolate (OpenGL only)
```
  /vis/viewer/interpolate ! ! ! ! export
```
This produces lots of files. You can change export format with (for example)
```
  /vis/ogl/set/exportFormat jpg
```
Then import them into your favourite movie maker - see https://geant4-userdoc.web.cern.ch/UsersGuides/ForApplicationDeveloper/html/Visualization/makingamovie.html#

B) THE OLD WAY

These files are inherited from the old "novice" example N03. They draw (and optionally, save) views using a macro loop. They have not been tested recently. Best to run in batch mode in the build directory. E.g.

./movies -m visTutor/exN03Vis12.mac
./movies -m visTutor/exN03Vis13.mac

John Allison 15th February 2021