From 8c66898765fb91aef13984de5c245c614723bab2 Mon Sep 17 00:00:00 2001
From: Cameron Gutman <aicommander@gmail.com>
Date: Thu, 15 Oct 2020 18:40:13 -0500
Subject: [PATCH] Dynamically update haptic effects instead of creating new
 players all the time

---
 Limelight/Input/HapticContext.m | 60 +++++++++++++++++++++------------
 1 file changed, 38 insertions(+), 22 deletions(-)

diff --git a/Limelight/Input/HapticContext.m b/Limelight/Input/HapticContext.m
index 66d8217..5f6e186 100644
--- a/Limelight/Input/HapticContext.m
+++ b/Limelight/Input/HapticContext.m
@@ -15,6 +15,7 @@
     GCControllerPlayerIndex _playerIndex;
     CHHapticEngine* _hapticEngine API_AVAILABLE(ios(13.0), tvos(14.0));
     id<CHHapticPatternPlayer> _hapticPlayer API_AVAILABLE(ios(13.0), tvos(14.0));
+    BOOL _playing;
 }
 
 -(void)cleanup API_AVAILABLE(ios(14.0), tvos(14.0)) {
@@ -30,42 +31,55 @@
 
 -(void)setMotorAmplitude:(unsigned short)amplitude API_AVAILABLE(ios(14.0), tvos(14.0)) {
     NSError* error;
-    
-    // Cancel the last haptic effect
-    if (_hapticPlayer != nil) {
-        [_hapticPlayer stopAtTime:0 error:&error];
-        _hapticPlayer = nil;
-    }
 
     // Check if the haptic engine died
     if (_hapticEngine == nil) {
         return;
     }
     
-    // Don't bother queuing a 0 amplitude haptic event
+    // Stop the effect entirely if the amplitude is 0
     if (amplitude == 0) {
+        if (_playing) {
+            [_hapticPlayer stopAtTime:0 error:&error];
+            _playing = NO;
+        }
+        
         return;
     }
 
-    CHHapticEventParameter* intensityParameter = [[CHHapticEventParameter alloc] initWithParameterID:CHHapticEventParameterIDHapticIntensity value:amplitude / 65536.0f];
-    CHHapticEvent* hapticEvent = [[CHHapticEvent alloc] initWithEventType:CHHapticEventTypeHapticContinuous parameters:[NSArray arrayWithObjects:intensityParameter, nil] relativeTime:0 duration:GCHapticDurationInfinite];
-    CHHapticPattern* hapticPattern = [[CHHapticPattern alloc] initWithEvents:[NSArray arrayWithObject:hapticEvent] parameters:[[NSArray alloc] init] error:&error];
+    if (_hapticPlayer == nil) {
+        // We must initialize the intensity to 1.0f because the dynamic parameters are multiplied by this value before being applied
+        CHHapticEventParameter* intensityParameter = [[CHHapticEventParameter alloc] initWithParameterID:CHHapticEventParameterIDHapticIntensity value:1.0f];
+        CHHapticEvent* hapticEvent = [[CHHapticEvent alloc] initWithEventType:CHHapticEventTypeHapticContinuous parameters:[NSArray arrayWithObject:intensityParameter] relativeTime:0 duration:GCHapticDurationInfinite];
+        CHHapticPattern* hapticPattern = [[CHHapticPattern alloc] initWithEvents:[NSArray arrayWithObject:hapticEvent] parameters:[[NSArray alloc] init] error:&error];
+        if (error != nil) {
+            Log(LOG_W, @"Controller %d: Haptic pattern creation failed: %@", _playerIndex, error);
+            return;
+        }
+        
+        _hapticPlayer = [_hapticEngine createPlayerWithPattern:hapticPattern error:&error];
+        if (error != nil) {
+            Log(LOG_W, @"Controller %d: Haptic player creation failed: %@", _playerIndex, error);
+            return;
+        }
+    }
+
+    CHHapticDynamicParameter* intensityParameter = [[CHHapticDynamicParameter alloc] initWithParameterID:CHHapticDynamicParameterIDHapticIntensityControl value:amplitude / 65536.0f relativeTime:0];
+    [_hapticPlayer sendParameters:[NSArray arrayWithObject:intensityParameter] atTime:CHHapticTimeImmediate error:&error];
     if (error != nil) {
-        Log(LOG_W, @"Controller %d: Haptic pattern creation failed: %@", _playerIndex, error);
+        Log(LOG_W, @"Controller %d: Haptic player parameter update failed: %@", _playerIndex, error);
         return;
     }
     
-    _hapticPlayer = [_hapticEngine createPlayerWithPattern:hapticPattern error:&error];
-    if (error != nil) {
-        Log(LOG_W, @"Controller %d: Haptic player creation failed: %@", _playerIndex, error);
-        return;
-    }
-    
-    [_hapticPlayer startAtTime:0 error:&error];
-    if (error != nil) {
-        _hapticPlayer = nil;
-        Log(LOG_W, @"Controller %d: Haptic playback start failed: %@", _playerIndex, error);
-        return;
+    if (!_playing) {
+        [_hapticPlayer startAtTime:0 error:&error];
+        if (error != nil) {
+            _hapticPlayer = nil;
+            Log(LOG_W, @"Controller %d: Haptic playback start failed: %@", _playerIndex, error);
+            return;
+        }
+        
+        _playing = YES;
     }
 }
 
@@ -95,6 +109,7 @@
         Log(LOG_W, @"Controller %d: Haptic engine stopped: %p", me->_playerIndex, stoppedReason);
         me->_hapticPlayer = nil;
         me->_hapticEngine = nil;
+        me->_playing = NO;
     };
     _hapticEngine.resetHandler = ^{
         HapticContext* me = weakSelf;
@@ -104,6 +119,7 @@
         
         Log(LOG_W, @"Controller %d: Haptic engine reset", me->_playerIndex);
         me->_hapticPlayer = nil;
+        me->_playing = NO;
         [me->_hapticEngine startAndReturnError:nil];
     };