SDL_RenderDrawLine is documented as drawing the line “to include both end points” and that’s exactly what I find it does when running on Windows (OpenGL renderer), Mac OS and Android. But on Linux (specifically Ubuntu because I haven’t had a chance to try it on anything else) it appears to draw the line exclusive of the end point, indeed if you specify the same coordinates for both the start point and the end point it draws nothing at all!
The same thing happens on two different PCs: one running 32-bit Ubuntu 16.04 and the other running 64-bit Ubuntu 16.04 in VirtualBox under Windows, so I’m assuming the graphics card is not to blame. The version of SDL is whatever is currently available from the Ubuntu repository.
I’m rather mystified by this inconsistency. Any thoughts as to the possible cause?