Created tutorial_mouse_coords (markdown)

tutorial_mouse_coords.md

@@ -0,0 +1,42 @@
+# Mouse & Input Coordinates
+
+## About
+
+The reason for this small tutorial is to clear up many common mistakes about input coordinates, obtaining mouse position and screen resolution, etc.
+
+## Hardware Display Coordinates
+
+Using hardware coordinates makes sense in the case of writing complex UIs meant to run on PC, such as editors, MMOs, tools, etc. Yet, make not as much sense outside of that scope. 
+
+The only way to reliably obtain this information is by using functions such as:
+
+```python
+OS.get_video_mode_size()
+Input.get_mouse_pos()
+```
+
+However, this is discouraged for pretty much any situation. Please do not use these functions unless you really know what you are doing.
+
+## Viewport Display Coordinates
+
+Godot uses viewports to display content, and viewports can be scaled by several options (see [Multiple Screen Resolutions](tutorial_multires) tutorial). Use, then, the functions in nodes to obtain the mouse coordinates and viewport size, for example:
+
+
+```python
+
+func _input(ev):
+   # Mouse in viewport coordinates
+
+   if (ev.type==InputEvent.MOUSE_BUTTON):
+       print("Mouse Click/Unclick at: ",ev.pos)
+   elif (ev.type==InputEvent.MOUSE_MOTION):
+       print("Mouse Motion at: ",ev.pos)
+
+   # Print the size of the viewport
+
+   print("Viewport Resolution is: ",get_viewport_rect().size)
+
+func _ready():
+   set_process_input(true)
+
+