What are some alternatives?
When comparing OpenGL and Allegro, you can also consider the following products
Vulkan - Vulkan is a new generation graphics and compute API that provides high-efficiency, cross-platform access to modern GPUs used in a wide variety of devices from PCs and consoles to mobile phones and embedded platforms.
SFML - SFML provides a simple interface to the various components of your PC, to ease the development of games and multimedia applications. It is composed of five modules: system, window, graphics, audio and network.
SDL - Simple DirectMedia Layer is a cross-platform multimedia library designed to provide low level...
MonoGame - MonoGame is an open source implementation of the Microsoft XNA 4 Framework.
GLFW - GLFW is an Open Source, multi-platform library for OpenGL, OpenGL ES and Vulkan development on the...