Created a nice utility library for doing animations, and used it in the ritual crafting UI.

animation.cpp

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+#include "animation.hpp"
+
+namespace components {
+  void Animation::play() {
+    if(!playing) {
+      current = 0;
+      subframe = 0.0f;
+      playing = true;
+    }
+  }
+
+  float Animation::twitching() {
+    switch(easing) {
+      case ease::NONE:
+        return 0.0;
+      case ease::SINE:
+        return ease::sine(float(frames) / subframe * ease_rate);
+      case ease::OUT_CIRC:
+        return ease::out_circ(ease::sine(float(frames) / subframe * ease_rate));
+      case ease::OUT_BOUNCE:
+        return ease::out_bounce(ease::sine(float(frames) / subframe * ease_rate));
+      case ease::IN_OUT_BACK:
+        return ease::in_out_back(ease::sine(float(frames) / subframe * ease_rate));
+      default:
+        dbc::sentinel(
+            fmt::format("Invalid easing {} given to animation",
+              int(easing)));
+    }
+  }
+
+  void Animation::step(sf::Vector2f& scale_out, sf::Vector2f& pos_out, sf::IntRect& rect_out) {
+    if(playing && current < frames) {
+      float tick = twitching();
+      scale_out.x = std::lerp(scale_out.x, scale_out.x + scale, tick);
+      scale_out.y = std::lerp(scale_out.y, scale_out.y + scale, tick);
+
+      if(stationary) {
+        pos_out.y = pos_out.y - (pos_out.y * scale_out.y - pos_out.y);
+      }
+
+      if(!simple) {
+        rect_out.position.x += current * frame_width;
+      }
+
+      subframe += speed;
+      current = int(subframe);
+    } else if(!looped) {
+      playing = false;
+      current = frames - 1;
+      subframe = float(frames - 1);
+
+      if(!simple) {
+        rect_out.position.x += current * frame_width;
+      }
+    } else {
+      playing = false;
+      current = 0;
+      subframe = 0.0f;
+    }
+  }
+}
+
+
+namespace animation {
+  using namespace components;
+  using namespace textures;
+
+  static AnimationManager MGR;
+  static bool initialized = false;
+
+  bool apply(Animation& anim, SpriteTexture& target) {
+    auto size = target.texture->getSize();
+    anim.frame_width = int(size.x) / (unsigned int)anim.frames;
+    sf::IntRect rect{{0,0}, {anim.frame_width, int(size.y)}};
+    sf::Vector2f scale{1.0, 1.0};
+    sf::Vector2f pos{0, 0};
+
+    anim.step(scale, pos, rect);
+
+    target.sprite->setTextureRect(rect);
+    target.sprite->setPosition(pos);
+    target.sprite->setScale(scale);
+
+    return anim.playing;
+  }
+
+  void init() {
+    if(!initialized) {
+      Config config("assets/animations.json");
+
+      for(auto& [name, data] : config.json().items()) {
+        auto anim = components::convert<Animation>(data);
+        MGR.animations.insert_or_assign(name, anim);
+      }
+
+      initialized = true;
+    }
+  }
+
+  Animation load(std::string name) {
+    return MGR.animations.at(name);
+  }
+}