[fpc-pascal] OpenGL and SDL frustrations

[Marco van de Voort]

In our previous episode, Anthony Walter said:
> And if you're not using GLSL shaders, then you don't need anything greater
> than Open 1.5. You can see the list of changes at the link below. With the
> exception of frame buffer objects (better known as render to texture) in
> version 3.0 and up, there's likely very little you're going to need in the
> 3.0+ realm of APIs you're ever going to need.
> 
> https://www.khronos.org/opengl/wiki/History_of_OpenGL#Summary_of_version_changes

PBO speeds up texture upload on most DX10+ cards.