sdl: haptic: Add documentation for HapticEffect interface veandco#315

Author: malashin

sdl/haptic.go

@@ -295,6 +295,7 @@ func (h *Haptic) Query() (uint32, error) {
 }
 
 // EffectSupported reports whether an effect is supported by a haptic device.
+// Pass pointer to a Haptic struct (Constant|Periodic|Condition|Ramp|LeftRight|Custom) instead of HapticEffect union.
 // (https://wiki.libsdl.org/SDL_HapticEffectSupported)
 func (h *Haptic) EffectSupported(he iHapticEffect) (bool, error) {
 	ret := int(C.SDL_HapticEffectSupported(
@@ -304,6 +305,7 @@ func (h *Haptic) EffectSupported(he iHapticEffect) (bool, error) {
 }
 
 // NewEffect creates a new haptic effect on a specified device.
+// Pass pointer to a Haptic struct (Constant|Periodic|Condition|Ramp|LeftRight|Custom) instead of HapticEffect union.
 // (https://wiki.libsdl.org/SDL_HapticNewEffect)
 func (h *Haptic) NewEffect(he iHapticEffect) (int, error) {
 	ret := int(C.SDL_HapticNewEffect(
@@ -313,6 +315,7 @@ func (h *Haptic) NewEffect(he iHapticEffect) (int, error) {
 }
 
 // UpdateEffect updates the properties of an effect.
+// Pass pointer to a Haptic struct (Constant|Periodic|Condition|Ramp|LeftRight|Custom) instead of HapticEffect union.
 // (https://wiki.libsdl.org/SDL_HapticUpdateEffect)
 func (h *Haptic) UpdateEffect(effect int, data iHapticEffect) error {
 	return errorFromInt(int(