Implement hitbox viewer (#81)

Reviewed-on: #81
Co-authored-by: Álex Román Núñez <eirexe@eirteam.moe>

src/fighter/baked_animation/runtime.rs

@@ -55,6 +55,29 @@ impl BakedFighterAnimations {
     pub fn frame_count(&self, kind: AnimKind) -> Option<u32> {
         self.clip(kind).map(|clip| clip.frames.len() as u32)
     }
+    /// Samples one bone in model space without depending on the runtime's
+    /// previous-frame buffers. Tooling uses this when the user scrubs between
+    /// unrelated frames.
+    pub fn sample_bone_model_transform(
+        &self,
+        frame: &FighterAnimationFrame,
+        bone: &str,
+        model_scale: FGi32,
+    ) -> Option<FixedMat4> {
+        let local = self.sample_pose(frame)?;
+        let index = self.bone_names.iter().position(|name| name == bone)?;
+        let mut model = vec![None; local.len()];
+        resolve_model_transform(index, &self.parents, local, &mut model).ok()?;
+        let scale = FixedMat4 {
+            cols: [
+                [model_scale, FGi32::ZERO, FGi32::ZERO, FGi32::ZERO],
+                [FGi32::ZERO, model_scale, FGi32::ZERO, FGi32::ZERO],
+                [FGi32::ZERO, FGi32::ZERO, model_scale, FGi32::ZERO],
+                [FGi32::ZERO, FGi32::ZERO, FGi32::ZERO, FGi32::ONE],
+            ],
+        };
+        Some(scale.mul(model[index]?))
+    }
     pub(super) fn clip(&self, kind: AnimKind) -> Option<&BakedAnimationClip> {
         self.clip_indices
             .get(&kind)
@@ -78,6 +101,26 @@ pub struct FighterBoneMatrices {
 pub struct FighterBoneIndexMap(pub HashMap<String, usize>);
 
 impl FighterBoneMatrices {
+    /// Samples a baked pose for a preview or other non-gameplay caller.
+    pub fn sample_baked_pose(
+        &mut self,
+        baked: &BakedFighterAnimations,
+        frame: &FighterAnimationFrame,
+        model_scale: FGi32,
+    ) -> bool {
+        let Some(pose) = baked.sample_pose(frame) else {
+            return false;
+        };
+        self.set_pose(
+            frame.kind,
+            &baked.bone_names,
+            &baked.parents,
+            pose,
+            model_scale,
+        );
+        true
+    }
+
     #[cfg(test)]
     pub(super) fn buffer_capacities(&self) -> [usize; 5] {
         [