Fix various runtime shenanigans

src/fighter/baked_animation/runtime.rs

@@ -71,6 +71,7 @@ pub struct FighterBoneMatrices {
     local_matrices: Vec<FixedMat4>,
     previous_local_matrices: Vec<FixedMat4>,
     model_matrices: Vec<Option<FixedMat4>>,
+    presentation_kind: Option<AnimKind>,
 }
 
 #[derive(Component, Clone, Debug, Default)]
@@ -138,6 +139,7 @@ impl FighterBoneMatrices {
     }
     pub(super) fn set_pose(
         &mut self,
+        kind: AnimKind,
         bone_names: &[String],
         parents: &[Option<usize>],
         local: &[FixedMat4],
@@ -166,6 +168,7 @@ impl FighterBoneMatrices {
         self.previous_local_matrices.reserve(local.len());
         self.model_matrices.reserve(local.len());
         std::mem::swap(&mut self.matrices, &mut self.previous_frame_matrices);
+        let animation_changed = self.presentation_kind != Some(kind);
         std::mem::swap(&mut self.local_matrices, &mut self.previous_local_matrices);
         self.local_matrices.clear();
         self.local_matrices.extend_from_slice(local);
@@ -189,6 +192,14 @@ impl FighterBoneMatrices {
                 model_scale.mul(matrix.expect("baked bone hierarchy should be valid"))
             }),
         );
+        // A state transition is a discontinuity, not an animation frame to
+        // interpolate from the previous clip.  Keep the presentation pose at
+        // the new clip's first/current frame immediately.
+        if animation_changed {
+            self.previous_local_matrices
+                .clone_from(&self.local_matrices);
+        }
+        self.presentation_kind = Some(kind);
     }
 }
 
@@ -218,6 +229,7 @@ pub fn update_fighter_bone_matrices(
             .get(&fighter.manifest)
             .expect("fighter manifest should be loaded before the match starts");
         matrices.set_pose(
+            frame.kind,
             &baked.bone_names,
             &baked.parents,
             pose,