libjpeg_turbo questions

[PrometheusPi]

@FelixTUD The script you gave me a while ago in March for installing all isaac dependencies works fine on hemera but I have to questions:

1.) You added your local libjpeg-turbo to the CMAKE_PREFIX_PATH but set -DISAAC_JPEG=OFF- doesn't that make setting the cmake path beforehand obsolete?

2.) From the code, I see an explicit warning that isaac should be installed with libjpeg. What are the drawbacks and why could we/you set -DISAAC_JPEG=OFF?

3.) How did you install libjpeg-turbo?

[PrometheusPi]

Regarding question 3.) @psychocoderHPC suggested the following solution:

assuming ~/src, ~/lib, and ~/build exist:

cd ~/src
git clone git@github.com:libjpeg-turbo/libjpeg-turbo.git
cd ~/build
cmake -DCMAKE_INSTALL_PREFIX=~/lib/libjpeg-turbo -DWITH_SIMD=OFF ../libjpeg-turbo/
# WITH_SIMD=OFF avoids using the `nasm` on hemera.  
make install

[ax3l]

What's the problem with nasm/simd compiles on Hemera? Will definitely cost performance/latency if this is disabled.

[PrometheusPi]

Building the isaac server without libjpeg allows that the simulation at least runs - with libjpeg enabled the simulation does not start. Both do not show any images.

[PrometheusPi]

Seems to be an issue with the version of libwebsockets. See https://github.com/ComputationalRadiationPhysics/picongpu/pull/2940

[PrometheusPi]

Solved when using libwebsocket 2.1-stable or 2.2-stable

[ax3l]

@PrometheusPi can you please open a new issue, about adding support for newer versions of libwebsockets? In the meantime, please let us update the docs of ISAAC to narrow down the currently supported versions of libwebsockets.