GLEW functions can't be found - c++

Question

I am on Ubuntu, writing an application using OpenGL, GLEW and GLFW. I am using Eclipse as my IDE, and am having problems when trying to use functions such as glGenRenderbuffer. I have a very similar structure set up under Windows but can't get it to work on Linux.
I am linking to the libraries glfw and GLEW. I am able to compile and run parts of my application and can initialize both GLFW and GLEW. From these test runs I learn the following:
OpenGL version: 4.2.0 NVIDIA 304.64
Using GLEW 1.6.0
However, I can't get the function glGenRenderbuffer (or other framebuffer functions) to compile. I have tried adding both EXT and ARB to the name, as well as playing around with glex.h without any luck. As far as I know, the purpose of GLEW is to handle all extension issues, right?
The source file (VolumeRenderer.cpp) includes are done like this:
#include <glm/gtc/matrix_transform.hpp>
#include <VolumeRenderer.h>
#include <GL/glew.h>
#include <GL/glfw.h>
Further down, I am trying to use the function like this (only partially complete function, of course):
bool VolumeRenderer::InitFramebuffers()
{
glGenRenderbuffers(1, &renderBufferObject_);
return true;
}
All I get is "function 'glGenRenderBuffers' could not be resolved".
Looking in the GL/glew.h header I am including, I found the following lines among others:
#define glGenRenderbuffers GLEW_GET_FUN(__glewGenRenderbuffers)
#define glGenRenderbuffersEXT GLEW_GET_FUN(__glewGenRenderbuffersEXT)
But the compiler still can't find the function. Is there anything I have forgotten, or maybe some tests and checks I can run to see what is happening?

Answer 1

Alright, so I got it to work by basically copying my Eclipse project file by file into a new, empty project. However, I did some other things before that. First, I moved around the includes as suggested in the helpful comments. I also removed things like glm. No success! Then I made a simple project in Eclipse with one single .cpp file, and linked to glfw and GLEW:
#include <GL/glew.h>
#include <GL/glfw.h>
#include <iostream>
#include <cstdlib>
int main()
{
if (glfwInit() != GL_TRUE) {
std::cout << "glfwInit() failed\n";
exit(1);
}
if (!glfwOpenWindow(800, 600, 8 , 8, 8, 8, 8, 8, GLFW_WINDOW)) {
std::cout << "glfwOpenWindow() failed\n";
exit(1);
}
char *glVersion = (char*)glGetString(GL_VERSION);
if (glVersion) {
std::cout << "OpenGL version: " << glVersion << "\n";
}
GLenum err = glewInit();
if (err != GLEW_OK) {
std::cout << "GLEW init failed: " << glewGetErrorString(err) << "\n";
exit(1);
} else {
std::cout << "Using GLEW " << glewGetString(GLEW_VERSION) << "\n";
}
GLuint buf;
glGenRenderbuffers(1, &buf);
exit(0);
}
That worked like a charm. I then tried to recreate my old problem by making another project with a similar file and include structure, and it seemed to work fine too. I then started a third, empty project where I simply made exact copies of the files that were originally giving me trouble. Now I have an exact copy of the original project (that now had the include order changed) with the exact same libraries linked to it, and it works. I still don't know what happened but I suspect that my project in Eclipse got messed up somehow, and never recovered even though I made some changes.