Fix bone resampling breaking hitbox interpolation (#73)

Reviewed-on: #73
Co-authored-by: Álex Román Núñez <eirexe@eirteam.moe>

src/fighter/baked_animation/mod.rs

@@ -8,7 +8,7 @@ pub use crate::math::fixed_transform::FixedMat4;
 pub use asset_baking::{BakedAnimationAssetProcessingPlugin, BakedAnimationPlugin};
 pub use runtime::{
     BakedAnimationClip, BakedFighterAnimations, FighterBoneIndexMap, FighterBoneMatrices,
-    update_fighter_bone_matrices,
+    resample_fighter_bone_matrices, update_fighter_bone_matrices,
 };
 
 pub const BAKED_ANIMATION_FPS: u32 = 60;
@@ -275,6 +275,31 @@ mod tests {
         assert_eq!(capacities, matrices.buffer_capacities());
     }
 
+    #[test]
+    fn same_frame_resample_preserves_previous_gameplay_pose() {
+        let names = ["root".into()];
+        let parents = [None];
+        let mut pose_a = FixedMat4::IDENTITY;
+        pose_a.translate(FGVec3::lit("1", "0", "0"));
+        let mut pose_b = FixedMat4::IDENTITY;
+        pose_b.translate(FGVec3::lit("2", "0", "0"));
+        let mut snapped_pose = FixedMat4::IDENTITY;
+        snapped_pose.translate(FGVec3::lit("3", "0", "0"));
+        let mut matrices = FighterBoneMatrices::default();
+
+        matrices.set_pose(AnimKind::Wait, &names, &parents, &[pose_a], FGi32::ONE);
+        matrices.set_pose(AnimKind::Wait, &names, &parents, &[pose_b], FGi32::ONE);
+        matrices.resample_pose(
+            AnimKind::Landing,
+            &names,
+            &parents,
+            &[snapped_pose],
+            FGi32::ONE,
+        );
+
+        assert_eq!(matrices.get_index(0), Some((pose_a, snapped_pose)));
+    }
+
     #[test]
     fn model_scale_affects_gameplay_bones_without_changing_visual_locals() {
         let mut root = FixedMat4::IDENTITY;

src/fighter/baked_animation/runtime.rs

@@ -144,6 +144,27 @@ impl FighterBoneMatrices {
         parents: &[Option<usize>],
         local: &[FixedMat4],
         model_scale: FGi32,
+    ) {
+        self.sample_pose(kind, bone_names, parents, local, model_scale, true);
+    }
+    pub(super) fn resample_pose(
+        &mut self,
+        kind: AnimKind,
+        bone_names: &[String],
+        parents: &[Option<usize>],
+        local: &[FixedMat4],
+        model_scale: FGi32,
+    ) {
+        self.sample_pose(kind, bone_names, parents, local, model_scale, false);
+    }
+    fn sample_pose(
+        &mut self,
+        kind: AnimKind,
+        bone_names: &[String],
+        parents: &[Option<usize>],
+        local: &[FixedMat4],
+        model_scale: FGi32,
+        advance_history: bool,
     ) {
         assert_eq!(
             bone_names.len(),
@@ -167,9 +188,11 @@ impl FighterBoneMatrices {
         self.local_matrices.reserve(local.len());
         self.previous_local_matrices.reserve(local.len());
         self.model_matrices.reserve(local.len());
-        std::mem::swap(&mut self.matrices, &mut self.previous_frame_matrices);
+        if advance_history {
+            std::mem::swap(&mut self.matrices, &mut self.previous_frame_matrices);
+            std::mem::swap(&mut self.local_matrices, &mut self.previous_local_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);
         self.model_matrices.resize(local.len(), None);
@@ -215,19 +238,70 @@ pub fn update_fighter_bone_matrices(
     manifests: Res<Assets<FighterManifest>>,
 ) {
     for (frame, animations, fighter, mut matrices, mut bone_indices) in &mut fighters {
-        let baked = baked_assets
-            .get(&animations.baked)
-            .expect("fighter baked animation asset should be loaded before the match starts");
-        assert_eq!(
-            baked.frame_rate, BAKED_ANIMATION_FPS,
-            "fighter baked animation rate does not match the simulation rate"
+        sample_fighter_bone_matrices(
+            frame,
+            animations,
+            fighter,
+            &mut matrices,
+            &mut bone_indices,
+            &baked_assets,
+            &manifests,
+            true,
         );
-        let pose = baked
-            .sample_pose(frame)
-            .expect("fighter animation frame should select a baked pose");
-        let manifest = manifests
-            .get(&fighter.manifest)
-            .expect("fighter manifest should be loaded before the match starts");
+    }
+}
+
+/// Resamples the current pose after collision-driven state transitions without
+/// advancing the previous-frame pose used for swept gameplay volumes.
+pub fn resample_fighter_bone_matrices(
+    mut fighters: Query<(
+        &FighterAnimationFrame,
+        &FighterAnimations,
+        &Fighter,
+        &mut FighterBoneMatrices,
+        &mut FighterBoneIndexMap,
+    )>,
+    baked_assets: Res<Assets<BakedFighterAnimations>>,
+    manifests: Res<Assets<FighterManifest>>,
+) {
+    for (frame, animations, fighter, mut matrices, mut bone_indices) in &mut fighters {
+        sample_fighter_bone_matrices(
+            frame,
+            animations,
+            fighter,
+            &mut matrices,
+            &mut bone_indices,
+            &baked_assets,
+            &manifests,
+            false,
+        );
+    }
+}
+
+fn sample_fighter_bone_matrices(
+    frame: &FighterAnimationFrame,
+    animations: &FighterAnimations,
+    fighter: &Fighter,
+    matrices: &mut FighterBoneMatrices,
+    bone_indices: &mut FighterBoneIndexMap,
+    baked_assets: &Assets<BakedFighterAnimations>,
+    manifests: &Assets<FighterManifest>,
+    advance_history: bool,
+) {
+    let baked = baked_assets
+        .get(&animations.baked)
+        .expect("fighter baked animation asset should be loaded before the match starts");
+    assert_eq!(
+        baked.frame_rate, BAKED_ANIMATION_FPS,
+        "fighter baked animation rate does not match the simulation rate"
+    );
+    let pose = baked
+        .sample_pose(frame)
+        .expect("fighter animation frame should select a baked pose");
+    let manifest = manifests
+        .get(&fighter.manifest)
+        .expect("fighter manifest should be loaded before the match starts");
+    if advance_history {
         matrices.set_pose(
             frame.kind,
             &baked.bone_names,
@@ -235,15 +309,23 @@ pub fn update_fighter_bone_matrices(
             pose,
             manifest.model_scale,
         );
-        if bone_indices.0.is_empty() {
-            bone_indices.0.extend(
-                baked
-                    .bone_names
-                    .iter()
-                    .enumerate()
-                    .map(|(index, name)| (name.clone(), index)),
-            );
-        }
+    } else {
+        matrices.resample_pose(
+            frame.kind,
+            &baked.bone_names,
+            &baked.parents,
+            pose,
+            manifest.model_scale,
+        );
+    }
+    if bone_indices.0.is_empty() {
+        bone_indices.0.extend(
+            baked
+                .bone_names
+                .iter()
+                .enumerate()
+                .map(|(index, name)| (name.clone(), index)),
+        );
     }
 }
 

src/fighter/mod.rs

@@ -183,7 +183,7 @@ impl Plugin for FighterPlugin {
                 GgrsSchedule,
                 (
                     (blast_zones::apply_blast_zones, ecb::update_ecb, ecb::decrement_ecb_lockout, state::state_collision_interrupt_system).chain(),
-                    baked_animation::update_fighter_bone_matrices,
+                    baked_animation::resample_fighter_bone_matrices,
                 )
                     .chain()
                     .in_set(GameplaySet::Collision),