Compile OpenGL_Example howto

[Lecrapouille]

For Linux: 1/ Replace #include <GLEW/glew.h> by #include <GL/glew.h> in OpenGL_Example.cpp 2/ Modify the Makefile to add

`pkg-config --libs glew --static glfw3`

So:

CC = g++
CFLAGS = -std=c++0x -c -Wall -O3
DEBUG =
ARFLAGS = -cvq
LDFLAGS =
EXECUTABLE = bin/OpenGL_Example
SOURCES = examples/OpenGL_Example.cpp
LIBSOURCENAMES = BeachLine.cpp Cell.cpp CircleEventQueue.cpp Diagram.cpp Edge.cpp Point2.cpp Vector2.cpp VoronoiDiagramGenerator.cpp
LIBSOURCEDIR = src/
LIBSOURCES = $(addprefix $(LIBSOURCEDIR), $(LIBSOURCENAMES))
OBJS = $(SOURCES:.cpp=.o)
LIBOBJS = $(LIBSOURCES:.cpp=.o)
LIB = bin/Voronoi.a

all : $(SOURCES) $(LIB) $(EXECUTABLE)

lib : $(LIB)

$(EXECUTABLE) : $(OBJS)
    $(CC) $(LDFLAGS) $(OBJS) $(LIB) -o $@ `pkg-config --libs glew --static glfw3`
    rm -rf $^

$(LIB) : $(LIBOBJS)
    ar $(ARFLAGS) $@ $^
    rm -rf $^

.cpp.o :
    $(CC) $(CFLAGS) $(DEBUG) $< -o $@

clean :
    rm -rf $(LIBSOURCEDIR)*.o $(EXECUTABLE) $(LIB)