First off, I'm relatively new to this. I'm looking forward to picking up both SDL2 as well as SFML2 libraries for game dev. (and other stuff).
Now I know for a fact that both SDL2 and SFML2 are capable of creating OpenGL enabled contexts, through which OpenGL graphics programming may be done.
But online, I've read discussions wherein people said something to the effect of "SDL 1.2 is software accelerated, SDL2 and SFML2 are hardware accelerated by default". I know that software rendering is graphics using CPU alone. While Hardware rendering uses graphics cards/pipeline.
So my question is, with regards to these game libraries:
Part 1: when someone says one is software/hardware acc.by default, what does he mean? Is it that (my guess) if say SFML2 is hardware acc. by default, even basic 2d graphics are done by it using hardware rendering as the backend pipeline to do it, even if I didn't explicitly do any hardware-rendering programming in the code?
Part 2: And if that is true, is there any option within these libraries to set that to software acceleration/rendering?
Part 3: Which of these 2 libraries (SDL2 vs SFML2) has better overall performance/speed?
Thanks in advance for any answer and apologies if you found the question dumb.
Cannot say anything about SFML (but almost sure things are very close), but for SDL it is as you say. In SDL1 2d drawing implemented as blitting directly on display surface, and then sending this surface to display - so mostly software (although minor hw acceleration is still possible). SDL2 have SDL_Renderer and textures (which are GPU-side images or render targets) and any basic drawing that uses renderer may be accelerated by one or another backend. Which backend will be chosen depends on system your program runs and user settings - e.g. it would default to opengl for linux, d3d for windows (but still can use opengl), opengles for android/ios, etc..
You can use software renderer either by explicitly calling SDL_CreateSoftwareRenderer, or hint SDL to use software driver, or even override it by setting SDL_RENDER_DRIVER environment variable.
If you intend to use opengl for 3d graphics - then you just ignore all that and create window with opengl context as usual, and never use SDL_Renderer.