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                      =================
                      = First warning =
                      =================

The shader used for the this series of experiments is very large. My
laptop has both an Intel Integrated Graphics Processor and an NVIDIA
GPU. This shader comes close to the limit of what the Intel compiler
can handle, and, if succesful, takes a long time to compile it. This
leads to delays of up to 30 seconds before any output is seen.

Furthermore,  minor  changes to the shader can easily cause it to be
too complex for the compiler to handle.  At  one point even a single
unnecessary semi-colon was enough to cause a problem. These problems
can result in the VGHD program crashing.

I have not had any problems when using the NVIDIA GPU,  but there is
still a short delay of about 5 seconds before any output appears.

The current version works on my laptop with either the Intel or  the
NVIDIA GPU, but it may not work on all systems.

In the delay between selecting a scene and it begining to produce an
output - either to the preview panel or to the full screen - then do
not click on anything.  The  VGHD  program seems to be in a somewhat
unstable state during these periods when starting any scene, but the
problem is very noticable with this shader.  My advice is to "sit on 
your hands" for at least 30 seconds. I suspect that there is a "race
condition" somewhere in the VGHD program or the  graphics  libraries
and drivers that it uses.  This  delay is also seen when VGHD starts
a new scene after finishing the previous one,  and  the  same advice
applies.

If you are using an Intel Integrated Gaphic processor then,  due  to
differences between systems, you may run into the same problems as I
had. If you do then you have the following options

  1) Use a different GPU if available.

  2) Simplify the shader.

Option 2 can be accomplished as follows

  1) Find the shader directory for this set of scenes.

     It should contain three files called

        TheEmu - Complex Functions - Data Panel Only
        TheEmu - Complex Functions - No Data Panel.fsh
        TheEmu - Complex Functions.fsh
  
  2) Rename

        TheEmu - Complex Functions.fsh

     to

        TheEmu - Complex Functions - Full.fsh

  3) Copy 

        TheEmu - Complex Functions - No Data Panel.fsh

     and rename the copy to be

        TheEmu - Complex Functions.fsh

or alternatively you can edit all of the scene files to use the  "No
Data Panel" version - but I do not recommend it.

The "No Data Panel" version the shader is much less complex than the
full version  (achieved using conditional compilation so the sources
are almost identical, just one line being different) and it ought to
run on any reasonable system.

A related problem when using the Intel Integrated Graphics processor
is that because it takes a long time to compile and load the  shader
program and because the VGHD elapsed time variable, u_Elapsed, seems
to start running before the process is complete then by the time the
image first appears a significant time has elapsed,  so much so that
much, or even all,  of the time allocated for the first function has
already elapsed and the start of the sequence of function images  is
lost or greatly curtailed.  This  is  not specific to the Intel GPU,
but is much more pronounced when using  it.  In  order  to  partialy
overcome this effect the time used in the shader is made to stay  at
zero for the first few seconds. This has the effect that any dynamic
effects only start when this initial delay expires, but as it is not
a long delay it is not a problem - I even like the effect.

=====================================================================

                        ==================
                        = Second Warning =
                        ==================

This series of experiments comprises a very large number of  scenes. 
If you install all of them where the VGHD is expecting to find  .scn
files then it will include all of them in its list of  scenes.  This
can cause a large delay to occur while it it initialising  the  list
after going to the VGHD full screen page, though once initialisation
is complete there should be no further delays of this sort.

My advice is to only install a partial set of these scenes. Even the
default set that I deliver is probably a bit too much.  Only install
any of the other scenes if you really want to look at them, and then
delete them afterwards.  Keep  the  scenes in the zip files and only
extract them when you want them.

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