joystick: Add an axis to allow strafing.

Modern gamepads typically have 2-3 D-pads and joysticks. This means
that it's desirable to be able to use one joystick for turning and
another for strafing. Add another axis in addition to the current X
and y axes that performs strafe movement.

1 files changed, 24 insertions, 4 deletions

diff --git a/src/d_event.h b/src/d_event.h
index 25334a96..230f3fa5 100644
--- a/src/d_event.h
+++ b/src/d_event.h
@@ -49,10 +49,30 @@ typedef enum
 // Event structure.
 typedef struct
 {
-    evtype_t	type;
-    int		data1;		// keys / mouse/joystick buttons
-    int		data2;		// mouse/joystick x move
-    int		data3;		// mouse/joystick y move
+    evtype_t type;
+
+    // Event-related data that depends on the type of event:
+    //
+    // ev_keydown/ev_keyup:
+    //    data1: Key code (from doomkeys.h) of the key that was
+    //           pressed or released.
+    //    data2: Ascii text of the character that was pressed,
+    //           shifted appropriately (eg. '$' if 4 was pressed
+    //           while shift was held).
+    //
+    // ev_mouse:
+    //    data1: Bitfield of buttons currently held down.
+    //           (bit 0 = left; bit 1 = right; bit 2 = middle).
+    //    data2: X axis mouse movement (turn).
+    //    data3: Y axis mouse movement (forward/backward).
+    //
+    // ev_joystick:
+    //    data1: Bitfield of buttons currently pressed.
+    //    data2: X axis mouse movement (turn).
+    //    data3: Y axis mouse movement (forward/backward).
+    //    data4: Third axis mouse movement (strafe).
+
+    int data1, data2, data3, data4;
 } event_t;