OpenGL 2.1 glCreateShader is undefined - c++

Question

I just started learning OpenGL with the help of FLTK because I need some GUI functionality. My IDE is VS13 on Windows 7 and my graphics card driver supports OpenGL 2.1.
What I did was simply to run one of their examples and try to modify it a little bit but it failed to compile with something that should be pretty basic - the glCreateShader method which is included in OpenGL 2.1, it says "Error: identifier "glCreateShader" is undefined" although there are a lot of other gl- functions that are recognized. Here is the code, my function is at the end. If I comment it out it builds and runs:
//
// "$Id: cube.cxx 8864 2011-07-19 04:49:30Z greg.ercolano $"
//
// Another forms test program for the Fast Light Tool Kit (FLTK).
//
// Modified to have 2 cubes to test multiple OpenGL contexts
//
// Copyright 1998-2010 by Bill Spitzak and others.
//
// This library is free software. Distribution and use rights are outlined in
// the file "COPYING" which should have been included with this file. If this
// file is missing or damaged, see the license at:
//
// http://www.fltk.org/COPYING.php
//
// Please report all bugs and problems on the following page:
//
// http://www.fltk.org/str.php
//
#include <config.h>
#include <FL/Fl.H>
#include <FL/Fl_Window.H>
#include <FL/Fl_Box.H>
#include <FL/Fl_Button.H>
#include <FL/Fl_Radio_Light_Button.H>
#include <FL/Fl_Slider.H>
#include <stdlib.h>
#include <string>
#include <FL/Fl_Gl_Window.H>
#include <FL/gl.h>
class cube_box : public Fl_Gl_Window {
void draw();
int handle(int);
public:
double lasttime;
int wire;
double size;
double speed;
cube_box(int x, int y, int w, int h, const char *l = 0)
: Fl_Gl_Window(x, y, w, h, l) {
lasttime = 0.0;
}
};
/* The cube definition */
float v0[3] = { 0.0, 0.0, 0.0 };
float v1[3] = { 1.0, 0.0, 0.0 };
float v2[3] = { 1.0, 1.0, 0.0 };
float v3[3] = { 0.0, 1.0, 0.0 };
float v4[3] = { 0.0, 0.0, 1.0 };
float v5[3] = { 1.0, 0.0, 1.0 };
float v6[3] = { 1.0, 1.0, 1.0 };
float v7[3] = { 0.0, 1.0, 1.0 };
#define v3f(x) glVertex3fv(x)
void drawcube(int wire) {
/* Draw a colored cube */
glBegin(wire ? GL_LINE_LOOP : GL_POLYGON);
glColor3ub(0, 0, 255);
v3f(v0); v3f(v1); v3f(v2); v3f(v3);
glEnd();
glBegin(wire ? GL_LINE_LOOP : GL_POLYGON);
glColor3ub(0, 255, 255); v3f(v4); v3f(v5); v3f(v6); v3f(v7);
glEnd();
glBegin(wire ? GL_LINE_LOOP : GL_POLYGON);
glColor3ub(255, 0, 255); v3f(v0); v3f(v1); v3f(v5); v3f(v4);
glEnd();
glBegin(wire ? GL_LINE_LOOP : GL_POLYGON);
glColor3ub(255, 255, 0); v3f(v2); v3f(v3); v3f(v7); v3f(v6);
glEnd();
glBegin(wire ? GL_LINE_LOOP : GL_POLYGON);
glColor3ub(0, 255, 0); v3f(v0); v3f(v4); v3f(v7); v3f(v3);
glEnd();
glBegin(wire ? GL_LINE_LOOP : GL_POLYGON);
glColor3ub(255, 0, 0); v3f(v1); v3f(v2); v3f(v6); v3f(v5);
glEnd();
}
void cube_box::draw() {
lasttime = lasttime + speed;
if (!valid()) {
glLoadIdentity();
glViewport(0, 0, w(), h());
glEnable(GL_DEPTH_TEST);
glFrustum(-1, 1, -1, 1, 2, 10000);
glTranslatef(0, 0, -10);
gl_font(FL_HELVETICA_BOLD, 16);
}
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glPushMatrix();
glRotatef(float(lasttime*1.6), 0, 0, 1);
glRotatef(float(lasttime*4.2), 1, 0, 0);
glRotatef(float(lasttime*2.3), 0, 1, 0);
glTranslatef(-1.0, 1.2f, -1.5);
glScalef(float(size), float(size), float(size));
drawcube(wire);
glPopMatrix();
gl_color(FL_GRAY);
glDisable(GL_DEPTH_TEST);
gl_draw(wire ? "Cube: wire" : "Cube: flat", -4.5f, -4.5f);
glEnable(GL_DEPTH_TEST);
}
int cube_box::handle(int e) {
switch (e) {
case FL_ENTER: cursor(FL_CURSOR_CROSS); break;
case FL_LEAVE: cursor(FL_CURSOR_DEFAULT); break;
}
return Fl_Gl_Window::handle(e);
}
Fl_Window *form;
Fl_Slider *speed, *size;
Fl_Button *button, *wire, *flat;
cube_box *cube;
void makeform(const char *name) {
form = new Fl_Window(510 + 390, 390, name);
new Fl_Box(FL_DOWN_FRAME, 20, 20, 350, 350, "");
new Fl_Box(FL_DOWN_FRAME, 510, 20, 350, 350, "");
speed = new Fl_Slider(FL_VERT_SLIDER, 390, 90, 40, 220, "Speed");
size = new Fl_Slider(FL_VERT_SLIDER, 450, 90, 40, 220, "Size");
wire = new Fl_Radio_Light_Button(390, 20, 100, 30, "Wire");
flat = new Fl_Radio_Light_Button(390, 50, 100, 30, "Flat");
button = new Fl_Button(390, 340, 100, 30, "Exit");
cube = new cube_box(23, 23, 344, 344, 0);
Fl_Box *b = new Fl_Box(FL_NO_BOX, cube->x(), size->y(),
cube->w(), size->h(), 0);
form->resizable(b);
b->hide();
form->end();
}
int main(int argc, char **argv) {
makeform(argv[0]);
// added to demo printing
form->begin();
form->end();
// end of printing demo
speed->bounds(4, 0);
speed->value(cube->speed = 1.0);
size->bounds(4, 0.01);
size->value(cube->size = 1.0);
flat->value(1);
cube->wire = 0;
form->label("cube");
form->show(argc, argv);
cube->show();
for (;;) {
if (form->visible() && speed->value()) {
if (!Fl::check()) break;
} // returns immediately
else {
if (!Fl::wait()) break;} // waits until something happens
cube->wire = wire->value();
cube->size = size->value();
cube->speed = speed->value();
cube->redraw();
if (Fl::readqueue() == button) break;
}
return 0;
}
//////////////////////////// Testing
GLuint CreateShader(GLenum eShaderType, const std::string &strShaderFile)
{
GLuint shader = glCreateShader(eShaderType);
return shader;
}