c# - Difference between XNA, DirectX and Monogame, SharpDX -

i have been learning c# time now. come non-developing background (means dont know actual working of different programming tools). started learning monogame few things confused me.

firstly says monogame open-source implementation of xna. mean? -that makes xna open-source -or takes features of xna , implements same function names etc. xna -any other

and allowed , legal? if yes, can copy app in app store , make own version? needs different legal?

secondly when installed monogame, sharpdx installed. when searched it, found sharpdx managed directx (i have never worked in directx). link between monogame , sharpdx (or xna , directx) , cant use monogame or sharpdx separately? , mean managed directx?

thirdly there more cross-platform c# frameworks other provided xamarin? cant find more.

what mean?

monogame implementation (same interface, different underpinnings) of xna

and allowed , legal?

i don't know xna's terms offhand, typically microsoft allows duplicates of sort (see original mono). can research on license xna if concerns you.

can copy app in app store , make own version? needs different legal?

i not lawyer (especially not copyright lawyer), couple of things steer in right direction, boils down copies ideas fine, copying concrete not.

• making match 3 game - okay
• using images candy crunch - not okay
• decompiling angry birds , using physics engine directly - not okay
• playing around angry birds , duplicating physics engine - okay

so if wrote , inspired fine, if take not fine. note there significant grey area when comes decompilation wouldn't related if want sell product. (or put on app store)

on less objective note, don't try , copy directly, if popular won't replicate success being same. find idea , tweak make more interesting @ least.

what link between monogame , sharpdx (or xna , directx) , cant use monogame or sharpdx separately?

monogame uses sharpdx on windows and/or xbox (both of have directx option). sharpdx externally maintained managed interface directx. rather redoing work use it. whether need depends on platform. useless on android or ios instance, since neither of platforms supports directx.

thirdly there more cross-platform c# frameworks other provided xamarin?

you need define framework , cross-platform if want answer question. instance mono cross-platform framework using .net framework definition of framework.