Why use SDL and OpenGL instead of just OpenGL?

Question

I've been seeing people combine SDL2 and OpenGL (glfw.h or glut.h) for a while now, I've done some research and found out SDL2 runs on OpenGL. So why does people combine these two? Some people discussed how they use SDL2 for making the window and OpenGL for everything else, but that doesn't make sense since OpenGL can create windows as well.

GLFWwindow *window = glfwCreateWindow(WIDTH, HEIGHT, "Opengl Tutorials", NULL, NULL);
glfwMakeContextCurrent(window); // Cause OpenGL to work on this window

glfwSetKeyCallback(window, KeyCallback); // Callback to handle key events
glfwSetCursorPosCallback(window, MouseCallback); // Callback to handle mouse motion events
glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);

Some also say they use SDL2 for 2D animations, but that doesn't make sense as OpenGL can do that as well. As I said before SDL2 uses OpenGL so anything SDL2 can do, OpenGL can do, SDL2 is a wrapper of OpenGL. So why do people still add SDL2 and OpenGL together? For example these.

• Game Engine using SDL2 and OpenGL
• Game Engine using SDL2 and OpenGL

Is there any advantage? Is there something I'm missing? I'm so confused. Why would you combine SDL2 with OpenGL even though SDL2 is only a wrapper?

Between this is all for C/C++ so that may clear up some confusion. When I refer to OpenGL I'm referring to glut.h or/and glfw.h not OpenGL by itself since I don't know if you can do that.

Answer 1

OpenGL only has functions to work with a graphics context, nothing else. You need at least a platform integration library to get such a context. But in reality you of course need more functionality, such as input handling. GLFW, GLUT and SDL2 are just different ways of getting such additional functionality. SDL2 is nice because it also includes audio and resource loading.

Answer 2

I was also wondering why. but yes I use SDL2 because it has the best api for sound.keyboard and joysticks I could find for sound processing. but you can make a window in SDL2 and draw 3d but GLFW seems to work easyer. Im trying to draw 2d and 3d together with SDL2 but its not working well but i just began.