Fixed bug 3446 - The haptic API does not allow to select the direction axes

meyraud705

Added Linux implementation, otherwise you get "Unsupported direction type" error.
Added documentation to explain why one would use SDL_HAPTIC_FIRST_AXIS.

include/SDL_haptic.h

@@ -338,7 +338,17 @@ typedef struct _SDL_Haptic SDL_Haptic;
 
 /**
  *  \brief Uses first axis only.
- *
+ *  For some device with only one axis (steering wheel,...),
+ *  SDL_HAPTIC_CARTESIAN does not work. SDL_HAPTIC_FIRST_AXIS can be used in 
+ *  this case.
+ *  Using SDL_HAPTIC_FIRST_AXIS is equivalent to :
+ *  \code
+ *  SDL_HapticDirection direction;
+ *  direction.type = SDL_HAPTIC_CARTESIAN;
+ *  direction.dir[0] = 1;
+ *  direction.dir[1] = 0;
+ *  direction.dir[2] = 0;
+ *  \endcode
  *  \sa SDL_HapticDirection
  */
 #define SDL_HAPTIC_FIRST_AXIS 3
@@ -451,6 +461,7 @@ typedef struct _SDL_Haptic SDL_Haptic;
  *  \sa SDL_HAPTIC_POLAR
  *  \sa SDL_HAPTIC_CARTESIAN
  *  \sa SDL_HAPTIC_SPHERICAL
+ *  \sa SDL_HAPTIC_FIRST_AXIS
  *  \sa SDL_HapticEffect
  *  \sa SDL_HapticNumAxes
  */

src/haptic/linux/SDL_syshaptic.c

@@ -718,7 +718,9 @@ SDL_SYS_ToDirection(Uint16 *dest, SDL_HapticDirection * src)
             *dest = (Uint16) tmp;
         }
         break;
-
+    case SDL_HAPTIC_FIRST_AXIS:
+        *dest = 0x4000;
+        break;
     default:
         return SDL_SetError("Haptic: Unsupported direction type.");
     }