glClearBufferfv - not declared in this scope? - c++

Question

EDIT: If anyone has this kind of error, and is using GLEW, when using OpenGL 4.5 functions, the following will help:
glewExperimental = GL_TRUE;
after that just initialize GLEW and you'll be fine.
I´m just starting out with OpenGL. Currently I am trying to clear the whole screen with red, as seen in this code here:
#include "GLFW/glfw3.h"
#define WIDTH 1280
#define HEIGHT 720
int main(void)
{
GLFWwindow *window;
if(!glfwInit()) {
return -1;
}
window = glfwCreateWindow(WIDTH, HEIGHT, "Test OpenGL", NULL, NULL);
if(!window) {
glfwTerminate();
return -1;
}
glfwMakeContextCurrent(window);
static GLfloat red[] = {1.0f, 0.0f, 0.0f, 1.0f};
glClearBufferfv(GL_COLOR, 0, red);
while(!glfwWindowShouldClose(window)) {
//glEnableClientState(GL_VERTEX_ARRAY);
//glDisableClientState(GL_VERTEX_ARRAY);
glfwSwapBuffers(window);
glfwPollEvents();
}
glfwTerminate();
return 0;
}
But there is a problem. I am using g++ to compile the code written in Code::Blocks. Also, I am learning with the OpenGL SuperBible 7th edition, where I got the code for clearing the screen with red. Before I was using glClearColor(255, 0, 0, 0) and then glClear(GL_COLOR_BUFFER_BIT);
But in this book the screen is cleared with glClearBufferfv, which throws the following exception:
error: 'glClearBufferfv' was not declared in this scope
Of course I want to use the code in the book for learning purposes, so it would be great, if that would work. Sadly, it doesn´t. Any idea, why?

Answer 1

glClearBufferfv is a newer OpenGL function, which means it is technically possible that a graphics card that speaks OpenGL doesn't support it. This means that the function needs to be loaded, either by you or by an OpenGL loading library, before you can use it.
The SuperBible example code comes with the gl3w loader as part of its s7 helper library. You could either:
use s7, which the other examples in the book will likely depend on as well
skip s7 and use gl3w or any other loader, like my personal favourite libepoxy
don't use a loader and load the functions you need by hand. This gets tedious very quick, but it does mean you get to see what's going on.
The GLFW documentation has some useful pointers as well.