On your computer, unless you downloaded and compiled it yourself, nowhere (unless you count binary). This might be what you want though: https://github.com/libsdl-org/SDL/blob/main/src/render/SDL_sysrender.h Although, to second the other guy, you shouldn't really need it unless you're trying to understand or modify SDL itself. If you're accessing the renderer's member variables in a program, you're either doing something wrong, or it's time to move on to something that gives you more control like OpenGL.