Merged in NRRPLT-8409-failed-fresh-install (pull request #87)

[NRRPLT-8409] Fix installation from source.

The VIRTUAL_ENV env var got reset by the deactivation of the virtual environment  used by install_template_experiments_requirements and generate_low_resolution_pbr_textures.

* [NRRPLT-8409] save VIRTUAL_ENV before deactivate
* [NRRPLT-8409] note about VIRTUAL_ENV

Approved-by: Ugo Albanese

nrp_functions

@@ -284,6 +284,7 @@ function nrp_rebase {
 }
 
 function install_template_experiments_requirements {
+  OLD_VIRTUAL_ENV="${VIRTUAL_ENV}"
   echo
   echo -------------------------
   echo Experiments
@@ -294,9 +295,11 @@ function install_template_experiments_requirements {
   requirements=$HBP/Experiments/template_requirements.txt # TODO(Luc) create $HBP/Experiments/templates and use a requirements.txt file per each template experiment
   $PIP_CMD install -r "${requirements}" || { echo EXPERIMENTS: PIP INSTALL ERROR; exit 1; }
   deactivate
+  export VIRTUAL_ENV="${OLD_VIRTUAL_ENV}"
 }
 
 function generate_low_resolution_pbr_textures {
+  OLD_VIRTUAL_ENV="${VIRTUAL_ENV}"
   cd "$HBP"
   $VIRTUALENV_CMD lower_res || { echo ERROR; exit 1; }
   source lower_res/bin/activate
@@ -305,6 +308,7 @@ function generate_low_resolution_pbr_textures {
   python "$HBP"/user-scripts/generatelowrespbr.py
   deactivate
   rm -rf lower_res
+  export VIRTUAL_ENV="${OLD_VIRTUAL_ENV}"
 }
 
 function process_models {

nrp_variables

@@ -58,6 +58,13 @@ export IGN_IP=127.0.0.1
 # NRP virtual env
 export NRP_VIRTUAL_ENV=$HOME/.opt/platform_venv
 export VIRTUAL_ENV=$NRP_VIRTUAL_ENV
+# NOTE the usage of the $VIRTUAL_ENV:
+# The make target `devinstall` installs NRP Python modules to VIRTUAL_ENV virtual environment.
+# One can change the $VIRTUAL_ENV for his/her own puproses,
+# but the NRP installation scripts and guides expect to find the artifacts at $NRP_VIRTUAL_ENV
+# Note as well, that if you activate and then deactivate virtual environment (even another one),
+# then the $VIRTUAL_ENV is unset and no longer available before you define it again.
+# Please, keep in mind the value of $VIRTUAL_ENV at different steps of installation/operation.
 
 # gzbridge & gzserver
 export PATH=$HOME/.opt/bbp/nrp-services:$PATH