Sorted out the animation vs. easing contradiction I believe. Now there's a separate easing_duration that's calculated from the total duration of all frames. Then a easing_position determines where in the total the animation is, which is fed to the asing functions as a ration of easing_position / easing_duration.

tools/animator.cpp

@@ -54,20 +54,11 @@ namespace animator {
   }
 
   void FSM::START(Event ev) {
-    switch(ev) {
-      case Event::TICK:
-        state(State::ANIMATE);
-        break;
-      default:
-        state(State::START);
-    }
+    state(State::ANIMATE);
   }
 
   void FSM::ANIMATE(Event ev) {
     switch(ev) {
-      case Event::TICK:
-        run_animation();
-        break;
       case Event::PLAY_STOP:
         if($anim.playing) {
           $anim.stop();
@@ -122,7 +113,7 @@ namespace animator {
     $anim.play();
   }
 
-  void FSM::run_animation() {
+  void FSM::update() {
     if($anim.playing) {
       $anim.update();
       $anim.apply(*$ui.sprite);
@@ -131,14 +122,6 @@ namespace animator {
     }
   }
 
-  void FSM::tick() {
-    auto [ticks, alpha] = $anim.commit();
-
-    for(int i = 0; i < ticks; i++) {
-      event(animator::Event::TICK, {});
-    }
-  }
-
   void FSM::check_update() {
     if($timer.getElapsedTime().toDuration() > 500ms) {
       try {
@@ -356,9 +339,9 @@ int main(int argc, char* argv[]) {
   main.init(sprite_name, anim_name, background);
 
   while(main.active()) {
-    main.tick();
-    main.check_update();
+    main.update();
     main.render();
+    main.check_update();
     main.handle_keyboard_mouse();
   }