Compile mitsuba in less than 10 minutes

compile_mistuba.sh

# go to the dir where you will download the source files
cd ...

# download the source files
git clone https://github.com/mitsuba-renderer/mitsuba

# go into the mitsuba folder
cd mitsuba

# copy the config file to build
cp build/config-linux-gcc.py build.py

# install all the necessary libraries
# if libpng12-dev fails to install just change it to -> libpng-dev
sudo apt-get install build-essential scons git libpng12-dev libjpeg-dev libilmbase-dev libxerces-c-dev libboost-all-dev libopenexr-dev libglewmx-dev libxxf86vm-dev libeigen3-dev libfftw3-dev

# get collada support
sudo apt-get install libcollada-dom-dev

# if you want to have the GUI install QT5
sudo apt-get install qt5-default libqt5opengl5-dev libqt5xmlpatterns5-dev

# start compiling and wait for "scons:Done building targets."
# if you meet problems here because there are no "(" in the prints it is 
# probably because you have scons > 3. Create an environment in Conda with 
# python 2.7, download scons 2.5 (https://scons.org/scons-251-is-available.html)
# and run "python setup.py install". Then, using the environement you have 
# created, run the command below.

# also if you meet problems with the boost library make sure that you add 
# the '-lboost_system' in config.py CXXFLAGS variable.

# if you meet problems with QT5 Widgets
# In mitsuba/data/scons/qt5.py change validmodules (line 392) to include the version number, e.g. QtCore => Qt5Core
# Change mitsuba/build/SConscript to their updated names, for instance, change line 28 to
# qtEnv.EnableQt5Modules(['Qt5Gui', 'Qt5Widgets', 'Qt5Core', 'Qt5OpenGL', 'Qt5Xml', 'Qt5XmlPatterns', 'Qt5Network'])
QT_SELECT=qt5 scons -j8

# update the pahts
source setpath.sh

# run mitsuba with the GUI
# if this fails due to libxerces, probably is because the version 3.1 is deprecated. Download it https://packages.ubuntu.com/xenial/amd64/libxerces-c3.1/download 
# and manually install it
mtsgui

Shouldn't line 11 be cp build/config-linux-gcc.py config.py?

On Ubuntu 16.04.7-amd64, I found the snippet qtEnv.EnableQt5Modules(['Qt5Gui', 'Qt5Widgets', 'Qt5Core', 'Qt5OpenGL', 'Qt5Xml', 'Qt5XmlPatterns', 'Qt5Network']) in the file mitsuba/src/mtsgui/SConscript

Also, I found the line defining qtEnv at location mitsuba/src/mtsgui/SConscript.
In addition, I had to edit the file mitsuba/data/scons and include 'Qt5Gui', 'Qt5Widgets', 'Qt5Core', 'Qt5OpenGL', 'Qt5Xml', 'Qt5XmlPatterns', 'Qt5Network' in the list validModules on line 374.