Add shifting ECB based on bone positions (melee-like)

src/fighter/baked_animation/runtime.rs

@@ -88,6 +88,12 @@ impl FighterBoneMatrices {
         ]
     }
 
+    pub fn get_by_idx(&self, index: usize) -> Option<(FixedMat4, FixedMat4)> {
+        Some((
+            *self.previous_frame_matrices.get(index)?,
+            *self.matrices.get(index)?,
+        ))
+    }
     pub fn get(&self, bone: &str) -> Option<(FixedMat4, FixedMat4)> {
         let index = self.bone_names.iter().position(|name| name == bone)?;
         Some((