Any downsides of moving from GDI+ to OpenGL?

Question

I recently moved the rendering part of a program of mine from GDI+ to OpenGL.

Now I'm wondering: are there any downsides to doing so?

For example, are there any versions of Windows (XP or later) that support GDI+ but not OpenGL?
Or, for example, is it possible for a lack of drivers (or poor drivers), or a lack of a graphics card, etc. to make OpenGL rendering impossible on a system on which GDI+ works fine?

(I understand the OpenGL might need to resort to software rendering on less capable systems, but aside from slowness, I'm wondering if it would ever simply not work correctly in a situation in which GDI+ would.)

Answer 1

It depends on the OpenGL version/profile you're using. Up to, inclusing Windows XP OpenGL-1.1 is available by default without additional drivers. Since Windows Vista the minimum available OpenGL version is OpenGL-1.4.

However if you need anything more than that, you're relying on the user installing the drivers that come from the GPU vendor; the drivers installed by default in a standard Windows installation don't cover OpenGL (for not perfectly sane reasons).

Programs and libraries that strongly depend on OpenGL-ES have resorted to incorporate fallbacks like ANGLE.

Answer 2

There are some idiosyncrasies, as for example: you cannot create a transparent OpenGL window, if transparency is disabled (which means, not at all, under XP). Otherwise, as datenwolf notes, there's ANGLE, but even that does not always work. Another option might be mesa3d compiled for the windows target, with software rendering enabled. This option might be the safest one and faster than the software OpenGL 1.1 implementation from Microsoft.