Compatibility OpenGL Core

Source: examples/retrocompat-libretro

The compatibility example targets a conservative OpenGL path and emphasizes diagnosability. It shows:

• compatibility hardware-render candidates,
• staged GL initialization,
• visible software fallback when hardware negotiation fails,
• distinct clear colors for initialization failures,
• diagnostic text overlays,
• performance sampling and display,
• GL cleanup on unload/reset.

Use this example when working on frontend compatibility or when adding diagnostic behavior to a hardware core. It demonstrates the project rule that failures should be visible and actionable instead of producing a black frame.

Failure-mode map:

• If hardware negotiation is rejected, the core returns true from load_game, shows a frontend message, and presents a software diagnostic frame.
• If hardware mode is accepted but no framebuffer is available, it shows a message and submits a duplicate frame with audio.
• If only clear symbols load, it still presents a clear-only hardware frame.
• If triangle rendering works but text setup fails, it keeps the triangle path alive and disables only the text overlay.
• If text rendering later fails, it destroys the text overlay and continues.

libretro-diagnostics provides the staged GL helpers and text/frame diagnostic building blocks used by this example.

Tutorial: OpenGL.