fix: ensure reversed tween for ctrl events (#682)

Author: Mivik

prpr/src/parse/rpe.rs

@@ -414,6 +414,19 @@ async fn parse_notes(
     Ok(notes)
 }
 
+fn reverse_tween(id: u8) -> u8 {
+    if id < 3 {
+        id
+    } else {
+        let rem = (id - 3) % 3;
+        match rem {
+            0 => id + 1,
+            1 => id - 1,
+            _ => id,
+        }
+    }
+}
+
 fn parse_ctrl_events(rpe: &[RPECtrlEvent], key: &str) -> AnimFloat {
     let vals: Vec<_> = rpe.iter().map(|it| it.value[key]).collect();
     if rpe.is_empty() || (rpe.len() == 2 && rpe[0].easing == 1 && (vals[0] - 1.).abs() < 1e-4) {
@@ -422,7 +435,9 @@ fn parse_ctrl_events(rpe: &[RPECtrlEvent], key: &str) -> AnimFloat {
     AnimFloat::new(
         rpe.iter()
             .zip(vals)
-            .map(|(it, val)| Keyframe::new(it.x, val, RPE_TWEEN_MAP.get(it.easing.max(1) as usize).copied().unwrap_or(RPE_TWEEN_MAP[0])))
+            .map(|(it, val)| {
+                Keyframe::new(it.x, val, reverse_tween(RPE_TWEEN_MAP.get(it.easing.max(1) as usize).copied().unwrap_or(RPE_TWEEN_MAP[0])))
+            })
             .collect(),
     )
 }