OpenGL Renderer

Post here all issues you have with OpenGL Renderer.

Current tasks and known bugs:

• Fix crash after second Device restart (type vid_restart several times in console to reproduce) (e9427ac939862e103e513a614ee1f9e7ae3c8df4)
• Fix bugs with dynamic lighting
  • Fix bugs with local lights (lamps, campfires, etc) (06bb7657fad7d6578820cdfbf4aa7701ee732496, 615152e548a309d4dd4df3d7beb982f18af7bae5)
• Rewrite sun lighting calculation from D3DXMath (#463, intersects with #261)
• Backend
  • Supported OpenGL versions:
    • 4.5
    • 4.1
    • 3.3
      • Implement shader pipeline that can work without GL_ARB_separate_shader_objects (b0e4de824046f77b9de378ea5d6f3de4e53b22a4)
        • Useful link to OpenGL Wiki
    • 3.1/3.0 maybe?
    • 2.2 maybe?
    • 2.0 maybe?
  • Implement OpenGL ES support
    • 3.x (make initial implementation for ES 3.x, if going straight to 2.0 isn't possible)
    • 2.0 (lower requirement to 2.0, if initial implementation was for 3.x)
  • Support for uniform buffer objects
  • Support MSAA
  • Support geometry shaders
  • Support compute shaders
  • Support tesselation shaders
• Shaders (two ways, should be supported both)
  • Use cross-compiler to compile shaders from DirectX renderer
    • Look into #258 for more info
  • Implement all shaders in GLSL (shaders/gl folder)
    • Implement vertex and fragment (pixel) shaders
      • Make implemented shaders work in all situations
        • Fix boxy sky textures with enabled Vertex Texture Fetch (#537)
        • Fix lighting glitches with G-buffer optimization enabled (r3_gbuffer_opt on)
        • Fix SSAO
        • Fix HBAO shader
    • MSAA support
    • Implement volumetric fog
    • Implement HDAO Ultra (compute shaders)
    • Implement tesselation

Start by reviewing the OpenGL renderer backend and the shaders/gl folder, then reproduce the listed renderer behavior with the relevant console commands such as vid_restart. The issue groups many possible tasks, including OpenGL version support, OpenGL ES, shader compilation, SSAO, and additional shader features; completion depends on selecting and defining one of those outstanding items.