'IL/il.h' file not found, but it exists

Question

When trying to build cegui the above mentioned header file cannot be found, while it clearly exists in /usr/local/include. Why does this happen?

[ 29%] Built target CEGUIBase-0
[ 32%] Built target CEGUIOpenGLRenderer-0
[ 32%] Built target CEGUINullRenderer-0
[ 32%] Built target CEGUIExpatParser
[ 32%] Built target CEGUILibXMLParser
[ 32%] Building CXX object cegui/src/ImageCodecModules/DevIL/CMakeFiles/CEGUIDevILImageCodec.dir/ImageCodec.cpp.o
/Users/Adam/Downloads/cegui-0.8.3/cegui/src/ImageCodecModules/DevIL/ImageCodec.cpp:33:10: fatal error: 
      'IL/il.h' file not found
#include <IL/il.h>
         ^
1 error generated.

Answer 1

I would imagine that you don't have /usr/local/include listed on your compile line. Have you added -I/usr/local/include to your CFLAGS? Or, because this output looks like it might be from a makefile using the cmake generator, have you added it via include_directories? If it's a cmake generated makefile, you can run make VERBOSE=1 to see the full compile line.