Undefined reference to glew

Question

while I am working on rendering fonts using ftgl in my opengl project I am encountering errors stating

g++ -o mygame Sample_GL3_2D.cpp glad.c -lGL -lglfw -ldl -lftgl  -lSOIL -I /usr/include/freetype2 -L/usr/local/lib -lfreetype
/usr/local/lib/libftgl.so: undefined reference to `__glewGenBuffers'
/usr/local/lib/libftgl.so: undefined reference to `glewInit'
/usr/local/lib/libftgl.so: undefined reference to `__glewBindVertexArray'
/usr/local/lib/libftgl.so: undefined reference to `__glewBindBuffer'
/usr/local/lib/libftgl.so: undefined reference to `__glewUniform3f'
/usr/local/lib/libftgl.so: undefined reference to `__glewVertexAttribPointer'
/usr/local/lib/libftgl.so: undefined reference to `__glewBufferData'
/usr/local/lib/libftgl.so: undefined reference to `__glewDeleteBuffers'
/usr/local/lib/libftgl.so: undefined reference to `__glewDeleteVertexArrays'
/usr/local/lib/libftgl.so: undefined reference to `__glewGenVertexArrays'
/usr/local/lib/libftgl.so: undefined reference to `__glewEnableVertexAttribArray'

these are my contents in Makefile

all:mygame

mygame: Sample_GL3_2D.cpp glad.c
    g++ -o mygame Sample_GL3_2D.cpp glad.c -lGL -lglfw -ldl -lftgl  -lSOIL -I /usr/include/freetype2 -L/usr/local/lib -lfreetype
clean:
    rm mygame

looks like the errors is being raised by the libftgl.so library. I have installed the GLEW using the glew packages in the ubuntu. but dont understand why it isn't being referenced.

You are not linking against glew, aren't you? – BDL Jan 17 '17 at 11:53 — BDL, Jan 17 '17 at 11:53

score 2 · Answer 1 · edited May 23 '17 at 10:29

You aren't referencing the GLEW library on the compile/link line. The -l flag to g++ is tells it to tell the linker to the link the library e.g. -lftgl tells it to look for the ftgllibrary and link it.

You don't have -lGLEW (or -lglew if the library is named using lowercase) so it isn't linked. Also see this answer error undefined reference to `FTExtrudeFont::FTExtrudeFont(char const*)'

Maybe the two of you should get together and try and help each other since you are appear to be trying to solve the same (homework?) problem.

Undefined reference to glew

1 Answers1