nixpkgs/pkgs/development/libraries/SDL/setup-hook.sh

addSDLPath () {
  if [ -e "$1/include/SDL" ]; then
    export SDL_PATH="$SDL_PATH $1/include/SDL"
    export SDL_LIB_PATH="$SDL_LIB_PATH -L$1/lib"
  fi
}

addEnvHooks "$hostOffset" addSDLPath