hello, i want to input random values to some parameters for a shader and see what kinds of images those random parameters would produce i want to keep a record of what random values were used also so i could use the same values in the future.

i am using hscript + shell scripting. i was trying two ways of doing this.

1) use a random expression for the shader variable. i.e. rand(system(date))
i was using the example hscript+unix shell scripts.


#! /bin/csh -f

#check to see if user suppled the correct number of arguments
#- exit if not

if ($#argv < 4) then
echo “USEAGE: ren_script <hip_file> <out_file> <start> <end>”
exit
endif

# set up user supplied arguments

set HIP_FILE = $1
set OUT_FILE = $2
set START = $3
set END = $4
set TEST

for i = $START to $END
echo ‘ch(“/obj/geo1/tx”)’
end

ENDCAT


the problem for this particular situation is:

-echo just prints out ‘ch(“/obj/geo1/tx”)’ instead of the actual value. in the textport window, this command works and prints out 0

-im not sure when the expression is evaluated. is the expression evaluated only when it is currently being rendered. unfortunately since echo was not working, i could not extract the value of the variable. would i have to “cook” the shader first in order to find out what the random variable would be?


2) feed the *.hip file a random number i generated in the unix shell. i.e. using gawk srand() and rand() functions.
i am havint all sorts of problems with this, i think this may be working:

set randomnumber = system( “unix gawk ‘BEGIN { srand();print rand() }’”)

problem is, i have this for loop



#! /bin/csh -f

#check to see if user suppled the correct number of arguments
#- exit if not

if ($#argv < 4) then
echo “USEAGE: ren_script <hip_file> <out_file> <start> <end>”
exit
endif

# set up user supplied arguments

set HIP_FILE = $1
set OUT_FILE = $2
set START = $3
set END = $4
set TEST = 22

for i = $START to $END
set TEST = 44
echo $TEST
end

ENDCAT



this doesnt set TEST for some reason and just prints out 22 when it should be 44, so i am not able to set the shader variable.

I haven't tested this but try escaping the single quotes with a \

so



echo ‘ch(“/obj/geo1/tx”)’

becomes

echo \'ch(“/obj/geo1/tx”)\'

Also in your second example it might be worth using setenv or set -g instead of just set. This will make the variables global and might do the trick.

To have an expression (like ch() ) evaluate, you need to put it in backticks – `, not ‘.

Also, ch() will just tell you what it is, it won’t set it. For that, you'll need the ‘opparm’ command.

– Antoine