# split pd-maths into pd-core and pd-image (0.2.3)

include/pd/core/tween.hpp

@@ -0,0 +1,161 @@
+#pragma once
+
+/*
+MIT License
+Copyright (c) 2024 - 2025 René Amthor (tobid7)
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+ */
+
+#include <pd/core/vec.hpp>
+
+namespace PD {
+template <typename T>
+class Tween {
+ public:
+  enum Effect {
+    Linear,
+    EaseInQuad,
+    EaseOutQuad,
+    EaseInOutQuad,
+    EaseInCubic,
+    EaseOutCubic,
+    EaseInOutCubic,
+    EaseInSine,
+    EaseOutSine,
+    EaseInOutSine,
+  };
+  Tween() {}
+  ~Tween() {}
+
+  void Update(float delta) {
+    time += delta / 1000.f;
+    if (time > tend) {
+      finished = true;
+      time = tend;
+    }
+  }
+
+  bool IsFinished() const { return finished; }
+
+  Tween& Finish() {
+    time = tend;
+    finished = true;
+    return *this;
+  }
+
+  Tween& From(const T& start) {
+    Reset();
+    this->start = start;
+    return *this;
+  }
+  Tween& To(const T& end) {
+    Reset();
+    this->end = end;
+    return *this;
+  }
+  Tween& In(float seconds) {
+    Reset();
+    tend = seconds;
+    return *this;
+  }
+  Tween& As(const Effect& e) {
+    effect = e;
+    return *this;
+  }
+  Tween& Reset() {
+    finished = false;
+    time = 0.f;
+    return *this;
+  }
+  /// @brief Probably usefull for fading colors by animation
+  /// Used to create this caus dont wanted to create a
+  /// fade effect fpr keyboard without having to Tween functions
+  /// @return
+  float Progress() const { return time / tend; }
+
+  Tween& Swap() {
+    T temp = start;
+    start = end;
+    end = temp;
+    return *this;
+  }
+
+  operator T() {
+    float t = 0.f;
+    switch (effect) {
+      case EaseInQuad:
+        t = time / tend;
+        return (end - start) * t * t + start;
+        break;
+      case EaseOutQuad:
+        t = time / tend;
+        return -(end - start) * t * (t - 2) + start;
+        break;
+      case EaseInOutQuad:
+        t = time / (tend / 2);
+        if (t < 1) return (end - start) / 2 * t * t + start;
+        t--;
+        return -(end - start) / 2 * (t * (t - 2) - 1) + start;
+        break;
+      case EaseInCubic:
+        t = time / tend;
+        return (end - start) * t * t * t + start;
+        break;
+      case EaseOutCubic:
+        t = time / tend;
+        t--;
+        return (end - start) * (t * t * t + 1) + start;
+        break;
+      // case EaseInOutCubic:
+      //   t = time / (tend / 2);
+      //   if (t < 1) return (end - start) / 2 * t * t * t + start;
+      //   t--;
+      //   return (end - start) / 2 * (t * t * t * 2) + start;
+      //   break;
+      case EaseInSine:
+        return -(end - start) * cos(time / tend * (M_PI / 2)) + (end - start) +
+               start;
+        break;
+      case EaseOutSine:
+        return (end - start) * sin(time / tend * (M_PI / 2)) + start;
+        break;
+      case EaseInOutSine:
+        return -(end - start) / 2 * (cos(M_PI * time / tend) - 1) + start;
+        break;
+
+      default:  // Linear
+        return (end - start) * (time / tend) + start;
+        break;
+    }
+  }
+
+ private:
+  Effect effect;
+  float time = 0.f;
+  // Defaulting to one to prevent div zero
+  // without a safetey check
+  // not implementing one cause if the user is
+  // Writing a In(0.f) its their fault
+  float tend = 1.f;
+  T start;
+  T end;
+  bool finished = false;
+};
+}  // namespace PD