hello! i am trying to build polyworld!
i have installed qt and gsl.

---------------------------------
--- BUILDING: Polyworld Project
---------------------------------
</polyworld/.bld/app/Makefile: polyworld.pro>
mkdir -p /polyworld/.bld/app
mkdir -p /polyworld/.bld/PwMoviePlayer
mkdir -p /polyworld/.bld/CalcComplexity
mkdir -p /polyworld/.bld/pwtxt
mkdir -p /polyworld/bin
cd /polyworld/.bld/app/ && make --file Makefile
make[1]: Entering directory `/polyworld/.bld/app'
gcc -c -pipe -Wno-deprecated -fopenmp -g -D_GLIBCXX_DEBUG_PEDANTIC -Wno-deprecated -fopenmp -Wall -W -D_REENTRANT -DQT_OPENGL_LIB -DQT_GUI_LIB -DQT_CORE_LIB -DQT_SHARED -I/usr/share/qt4/mkspecs/linux-g++ -I/polyworld -I/usr/include/qt4/QtCore -I/usr/include/qt4/QtGui -I/usr/include/qt4/QtOpenGL -I/usr/include/qt4 -I/polyworld -I../../agent -I../../app -I../../complexity -I../../environment -I../../graphics -I../../motion -I../../ui -I../../utils -I/usr/include/GL -I/usr/X11R6/include -I/polyworld -I/polyworld -I. -o debug.o /polyworld/app/debug.cp
gcc: error trying to exec 'cc1plus': execvp: No such file or directory
Assembler messages:
Fatal error: can't create debug.o: Permission denied
make[1]: *** [debug.o] Error 1
make[1]: Leaving directory `/polyworld/.bld/app'
make: *** [app] Error 2

i have read that you may see this problem if you dont have g++ installed. you should be able to easily install it using your package manager (i.e. synaptic?), but i forget the name of the exact package to look for, so do a quick search for the name; its something with "essentials" in the name, i believe.

first verify the above error message. if, after you can get rid of that message and this second error still appears, make sure you do have write permissions to wherever it is trying to create "debug.o".