SDL: More responsive rumble

CHANGES

@@ -100,6 +100,7 @@ Misc:
  - Util: Add PRIz macro for libc versions that don't support %z
  - SDL: Increase default audio buffer size to 1024 samples
  - GBA: Add override for Pokemon Pinball: Ruby and Sapphire rumble
+ - SDL: More responsive rumble
 
 0.4.1: (2016-07-11)
 Bugfixes:

src/platform/sdl/sdl-events.c

@@ -25,7 +25,8 @@
 #endif
 
 #define GYRO_STEPS 100
-#define RUMBLE_PWM 20
+#define RUMBLE_PWM 16
+#define RUMBLE_STEPS 2
 
 mLOG_DEFINE_CATEGORY(SDL_EVENTS, "SDL Events");
 
@@ -167,6 +168,7 @@ bool mSDLAttachPlayer(struct mSDLEvents* events, struct mSDLPlayer* player) {
 	player->rumble.d.setRumble = _mSDLSetRumble;
 	CircleBufferInit(&player->rumble.history, RUMBLE_PWM);
 	player->rumble.level = 0;
+	player->rumble.activeLevel = 0;
 	player->rumble.p = player;
 #endif
 
@@ -568,6 +570,7 @@ static void _mSDLSetRumble(struct mRumble* rumble, int enable) {
 	if (!sdlRumble->p->joystick || !sdlRumble->p->joystick->haptic || !SDL_HapticRumbleSupported(sdlRumble->p->joystick->haptic)) {
 		return;
 	}
+	int8_t originalLevel = sdlRumble->level;
 	sdlRumble->level += enable;
 	if (CircleBufferSize(&sdlRumble->history) == RUMBLE_PWM) {
 		int8_t oldLevel;
@@ -575,8 +578,17 @@ static void _mSDLSetRumble(struct mRumble* rumble, int enable) {
 		sdlRumble->level -= oldLevel;
 	}
 	CircleBufferWrite8(&sdlRumble->history, enable);
-	if (sdlRumble->level) {
-		SDL_HapticRumblePlay(sdlRumble->p->joystick->haptic, sdlRumble->level / (float) RUMBLE_PWM, 20);
+	if (sdlRumble->level == originalLevel) {
+		return;
+	}
+	float activeLevel = ceil(RUMBLE_STEPS * sdlRumble->level / (float) RUMBLE_PWM) / RUMBLE_STEPS;
+	if (fabsf(sdlRumble->activeLevel - activeLevel) < 0.75 / RUMBLE_STEPS) {
+		return;
+	}
+	sdlRumble->activeLevel = activeLevel;
+	if (sdlRumble->activeLevel > 0.5 / RUMBLE_STEPS) {
+		SDL_HapticRumbleStop(sdlRumble->p->joystick->haptic);
+		SDL_HapticRumblePlay(sdlRumble->p->joystick->haptic, activeLevel, 500);
 	} else {
 		SDL_HapticRumbleStop(sdlRumble->p->joystick->haptic);
 	}

src/platform/sdl/sdl-events.h

@@ -63,6 +63,7 @@ struct mSDLPlayer {
 		struct mSDLPlayer* p;
 
 		int level;
+		float activeLevel;
 		struct CircleBuffer history;
 	} rumble;
 #endif