fix up morph target animations and add stopAnimation function

example/lib/main.dart

@@ -81,6 +81,11 @@ class _MyAppState extends State<MyApp> {
                       onPressed: () =>
                           _filamentController.playAnimation(0, loop: _loop),
                       child: const Text('play animation')),
+                  ElevatedButton(
+                      onPressed: () {
+                        _filamentController.stopAnimation();
+                      },
+                      child: const Text('stop animation')),
                   Checkbox(
                       onChanged: (_) => setState(() {
                             _loop = !_loop;
@@ -108,13 +113,15 @@ class _MyAppState extends State<MyApp> {
                         final numWeights = 8;
                         final totalFrames = framerate * totalSecs;
                         final frames = List.generate(
-                                totalFrames,
+                            totalFrames,
-                                (frame) => List.filled(
+                            (frame) =>
-                                    numWeights, frame / totalFrames))
+                                List.filled(numWeights, frame / totalFrames));
-                            .reduce((accum, next) => accum + next);
 
                         _filamentController.animate(
-                            frames, numWeights, framerate.toDouble());
+                            frames.reduce((a, b) => a + b),
+                            numWeights,
+                            totalFrames,
+                            1000 / framerate.toDouble());
                       },
                       child: const Text('animate weights')),
                   Builder(

ios/src/FilamentViewer.cpp

@@ -539,9 +539,11 @@ namespace polyvox
     Log("Set viewport to width: %d height:  %d scaleFactor : %f", width, height, contentScaleFactor);
   }
 
-  void FilamentViewer::animateWeights(float *data, int numWeights, int numFrames, float frameRate)
+  void FilamentViewer::animateWeights(float *data, int numWeights, int numFrames, float frameLengthInMs)
   {
-    morphAnimationBuffer = std::make_unique<MorphAnimationBuffer>(data, numWeights, numFrames, 1000 / frameRate);
+    // assert numWeights == asset.numWeights ?
+    Log("Making morph animation buffer with %d weights across %d frames and frame length %f ms ", numWeights, numFrames, frameLengthInMs);
+    morphAnimationBuffer = std::make_unique<MorphAnimationBuffer>(data, numWeights, numFrames, frameLengthInMs);
   }
 
   void FilamentViewer::updateMorphAnimation()
@@ -549,20 +551,19 @@ namespace polyvox
 
     if (morphAnimationBuffer->frameIndex >= morphAnimationBuffer->numFrames)
     {
+      duration<double, std::milli> dur = high_resolution_clock::now() - morphAnimationBuffer->startTime;
+      Log("Morph animation completed in %f ms (%d frames at framerate %f), final frame was %d", dur.count(), morphAnimationBuffer->numFrames, 1000 / morphAnimationBuffer->frameLengthInMs, morphAnimationBuffer->frameIndex);
       morphAnimationBuffer = nullptr;
-      return;
+    } else if (morphAnimationBuffer->frameIndex == -1)
-    }
-
-    if (morphAnimationBuffer->frameIndex == -1)
     {
       morphAnimationBuffer->frameIndex++;
-      morphAnimationBuffer->startTime = std::chrono::high_resolution_clock::now();
+      morphAnimationBuffer->startTime = high_resolution_clock::now();
       applyWeights(morphAnimationBuffer->frameData, morphAnimationBuffer->numWeights);
     }
     else
     {
-      std::chrono::duration<double, std::milli> dur = std::chrono::high_resolution_clock::now() - morphAnimationBuffer->startTime;
+      duration<double, std::milli> dur = high_resolution_clock::now() - morphAnimationBuffer->startTime;
-      int frameIndex = dur.count() / morphAnimationBuffer->frameLength;
+      int frameIndex = static_cast<int>(dur.count() / morphAnimationBuffer->frameLengthInMs);
       if (frameIndex != morphAnimationBuffer->frameIndex)
       {
         morphAnimationBuffer->frameIndex = frameIndex;
@@ -579,15 +580,20 @@ namespace polyvox
     }
   }
 
+  void FilamentViewer::stopAnimation() {
+    // TODO - does this need to be threadsafe?
+    embeddedAnimationBuffer = nullptr;
+  }
+
   void FilamentViewer::updateEmbeddedAnimation() {
-    duration<double> dur = duration_cast<duration<double>>(std::chrono::high_resolution_clock::now() - embeddedAnimationBuffer->lastTime);
+    duration<double> dur = duration_cast<duration<double>>(high_resolution_clock::now() - embeddedAnimationBuffer->lastTime);
     float startTime = 0;
     if(!embeddedAnimationBuffer->hasStarted) {
       embeddedAnimationBuffer->hasStarted = true;
-      embeddedAnimationBuffer->lastTime = std::chrono::high_resolution_clock::now();
+      embeddedAnimationBuffer->lastTime = high_resolution_clock::now();
     } else if(dur.count() >= embeddedAnimationBuffer->duration) {
       if(embeddedAnimationBuffer->loop) {
-        embeddedAnimationBuffer->lastTime = std::chrono::high_resolution_clock::now();
+        embeddedAnimationBuffer->lastTime = high_resolution_clock::now();
       } else {
         embeddedAnimationBuffer = nullptr;
         return;

ios/src/FilamentViewer.hpp

@@ -76,12 +76,12 @@ namespace polyvox {
       MorphAnimationBuffer(float* frameData,
                            int numWeights,
                            int numFrames,
-                           float frameLength) : frameData(frameData), numWeights(numWeights), numFrames(numFrames), frameLength(frameLength) {
+                           float frameLength) : frameData(frameData), numWeights(numWeights), numFrames(numFrames), frameLengthInMs(frameLength) {
       }
       
       int frameIndex = -1;
       int numFrames;
-      float frameLength;
+      float frameLengthInMs;
       time_point_t startTime;
       
       float* frameData;
@@ -102,10 +102,32 @@ namespace polyvox {
             unique_ptr<vector<string>> getTargetNames(const char* meshName);
             unique_ptr<vector<string>> getAnimationNames();
             Manipulator<float>* manipulator;
+            
+            
+            ///
+            /// Manually set the weights for all morph targets in the assets to the provided values.
+            /// See [animateWeights] if you want to automatically
+            ///
             void applyWeights(float* weights, int count);
-            void animateWeights(float* data, int numWeights, int length, float frameRate);
 
+            ///
+            /// Update the asset's morph target weights every "frame" (which is an arbitrary length of time, i.e. this is not the same as a frame at the framerate of the underlying rendering framework).
+            /// Accordingly:
+            ///       length(data) = numWeights * numFrames
+            ///       total_animation_duration_in_ms = number_of_frames * frameLengthInMs
+            ///
+            void animateWeights(float* data, int numWeights, int numFrames, float frameLengthInMs);
+
+            ///  
+            /// Play an embedded animation (i.e. an animation node embedded in the GLTF asset). If [loop] is true, the animation will repeat indefinitely.
+            ///
             void playAnimation(int index, bool loop);
+
+            ///
+            /// Immediately stop the currently playing animation. NOOP if no animation is playing.
+            ///
+            void stopAnimation();
+
             bool setCamera(const char* nodeName);
             void destroySwapChain();
             void createSwapChain(void* surface);

lib/filament_controller.dart

@@ -17,16 +17,18 @@ abstract class FilamentController {
   Future<List<String>> getTargetNames(String meshName);
   Future<List<String>> getAnimationNames();
   Future releaseSourceAssets();
-  Future playAnimation(int index, {bool loop=false});
+  Future playAnimation(int index, {bool loop = false});
+  Future stopAnimation();
   Future setCamera(String name);
 
   ///
-  /// Set the weights of all morph targets in the mesh to the specified weights at successive frames (where [framerate] is the number of times per second the weights should be updated).
+  /// Set the weights of all morph targets in the mesh to the specified weights at successive frames (where each frame requires a duration of [frameLengthInMs].
   /// Accepts a list of doubles representing a sequence of "frames", stacked end-to-end.
   /// Each frame is [numWeights] in length, where each entry is the weight to be applied to the morph target located at that index in the mesh primitive at that frame.
   /// In other words, weights is a contiguous sequence of floats of size W*F, where W is the number of weights and F is the number of frames
   ///
-  Future animate(List<double> weights, int numWeights, double frameRate);
+  Future animate(
+      List<double> data, int numWeights, int numFrames, double frameLengthInMs);
   Future createMorpher(String meshName, List<int> primitives);
   Future zoom(double z);
 }
@@ -45,7 +47,7 @@ class PolyvoxFilamentController extends FilamentController {
     _channel = MethodChannel("app.polyvox.filament/filament_view_$id");
     _channel.setMethodCallHandler((call) async {
       print("Received Filament method channel call : ${call.method}");
-      if(call.method == "ready") {
+      if (call.method == "ready") {
         onFilamentViewCreatedHandler?.call(_id);
         return Future.value(true);
       } else {
@@ -105,14 +107,15 @@ class PolyvoxFilamentController extends FilamentController {
   }
 
   Future<List<String>> getAnimationNames() async {
-    var result = (await _channel.invokeMethod("getAnimationNames"))
+    var result =
-        .cast<String>();
+        (await _channel.invokeMethod("getAnimationNames")).cast<String>();
     return result;
   }
 
-  Future animate(List<double> weights, int numWeights, double frameRate) async {
+  Future animate(List<double> weights, int numWeights, int numFrames,
-    await _channel
+      double frameLengthInMs) async {
-        .invokeMethod("animateWeights", [weights, numWeights, frameRate]);
+    await _channel.invokeMethod(
+        "animateWeights", [weights, numWeights, numFrames, frameLengthInMs]);
   }
 
   Future releaseSourceAssets() async {
@@ -127,8 +130,12 @@ class PolyvoxFilamentController extends FilamentController {
     await _channel.invokeMethod("createMorpher", [meshName, primitives]);
   }
 
-  Future playAnimation(int index, {bool loop=false}) async {
+  Future playAnimation(int index, {bool loop = false}) async {
-    await _channel.invokeMethod("playAnimation", [index,loop]);
+    await _channel.invokeMethod("playAnimation", [index, loop]);
+  }
+
+  Future stopAnimation() async {
+    await _channel.invokeMethod("stopAnimation");
   }
 
   Future setCamera(String name) async {