OpenGL Graphics API

OpenGL (Open Graphics Library) is a cross-language, cross-platform application programming interface (API) for rendering 2D and 3D vector graphics, maintained by the Khronos Group, an open industry consortium. Originally developed by Silicon Graphics Inc. (SGI) in 1992 (version 1.0 released on June 30, 1992), OpenGL evolved from earlier graphics APIs (IRIS GL) and has been the industry standard for hardware-accelerated graphics for over 30 years. Key features: fixed-function pipeline: the original OpenGL 1.x pipeline provided a fixed-function approach where vertices and fragments were processed through predefined stages (modelview/projection transforms, lighting, texturing, alpha blending, depth testing). Programmable pipeline: OpenGL 2.0 (2004) introduced the OpenGL Shading Language (GLSL) for vertex and fragment shaders, allowing developers to write custom programs for each pipeline stage. OpenGL 3.3+ (2010) introduced the core profile, deprecating the fixed-function pipeline in favor of fully programmable shaders. Geometry shaders (3.2), tessellation shaders (4.0), and compute shaders (4.3) were added for advanced techniques. State machine: OpenGL operates as a state machine where rendering commands are affected by the current state (bound textures, enabled blending, depth test mode). VBOs and VAOs: Vertex Buffer Objects for storing vertex data in GPU memory, Vertex Array Objects for encapsulating vertex attribute configurations. FBOs: Framebuffer Objects for off-screen rendering, enabling render-to-texture, shadow maps, and post-processing. Cross-platform: Windows (WGL), Linux (GLX), macOS (CGL, deprecated since 10.14), and mobile (via OpenGL ES). Supported by virtually all GPU vendors (NVIDIA, AMD, Intel). While deprecated by Apple in favor of Metal, OpenGL remains widely used. Multiple licenses.