Add To Scene OpenGL - c++

Question

I am trying to create a simple function that adds openGL code into my MainLoop.
For example, using win->AddToScene("glBegin(GL_TRIANGLES); glVertex3f( 0.0f, 1.0f, 0.0f); glVertex3f( 1.0f,-1.0f, 0.0f); glVertex3f(-1.0f,-1.0f, 0.0f); glEnd(); ");
I am trying to do this using Arrays, but it isn't working as far what I have.
Code:
std::vector< int > arr;
void Window::MainLoop()
{
do
{
glfwMakeContextCurrent(window);
glFlush();
glfwPollEvents();
for(int i = 0; i < arr.size(); i++)
{
arr[i];
}
glfwSwapBuffers(window);
}
while(running && !glfwWindowShouldClose(window));
}
void Window::AddToScene(char child[100]){
for(unsigned int i = 0; i < arr.size(); i++){
arr.push_back(*child);
}
}
Are the arrays a way to do it, or do I have to do something completely else?
Thanks

Answer 1

Props for creativity. Just FYI what you want to do wouldn't work that way in interpreted languages either. In those you'd have to use some eval statement.
It should be noted that it's perfectly possible to implement an interpreter for a small custom toy language (or rather command execution list) in C that does exactly as you envision.
However as far as adding geometry to your scene goes: You're barking up the completely wrong tree! A scene solely consists of what is drawn not how it is drawn. Your mistake in thinking is, that you mistook the glVertex calls as what is important. What's actually important are the numbers that go into it.
Think about something like this:
glBegin(…);
for(size_t i = 0; i < vertices.length(); ++i){
glVertex3f(vertices[i].x, vertices[i].y, vertices[i].z);
}
glEnd();
However all these function calls are super inefficient. What you actually want to do is rather this, i.e. using Vertex Arrays:
glVertexPointer(3, GL_FLOAT, 0, &vertices[0]);
glDrawArrays(…, 0, vertices.length());
Last step would be dropping the old style OpenGL functions and transition to generic vertex attributes and vertex buffer object; but that is easy enough once you master old style vertex arrays.