2 files changed, 112 insertions, 4 deletions
diff --git a/src/interpolation.rs b/src/interpolation.rs
index de6b6df..d088bf8 100644
--- a/src/interpolation.rs
+++ b/src/interpolation.rs
@@ -1,4 +1,17 @@
-use std::ops::{Add, Mul, Sub};
+// NOTE: This entire file would need to be reworked to handle functions like bezier curves/any other fn involving multiple points.
+//       Someone should do this at some point.
+//
+//       This likely would only be slightly breaking; ie the most commonly used portions of AnimationTrack would remain in-tact
+//       however, the internals of a KeyFrame would change immensely and be (more or less) impossible to keep
+
+use std::ops::{Add, Index, Mul, Sub};
+
+// For when RFC1733 finally passes
+// trait AcceptableValueType<ValueType> = PartialOrd
+//   + Copys
+//   + Add<Output = ValueType>
+//   + Sub<Output = ValueType>
+//   + Mul<f64, Output = ValueType>;
 
 pub fn raw_lerp<T>(a: T, b: T, t: f64) -> T
 where
@@ -7,11 +20,13 @@ where
   a + (b - a) * t
 }
 
+#[derive(Clone, Copy)]
 pub enum TimingFunction {
   Lerp,
 }
+#[derive(Clone, Copy, PartialEq, PartialOrd)]
+// We could make a TimeType generic (I initially did), however it's safe to assume we use a 64-bit float for this
 pub struct KeyFrame<ValueType> {
-  // We could make a TimeType generic (I initially did), however it's safe to assume we use a 64-bit float for this
   pub time: f64,
   pub val: ValueType,
 }
@@ -28,7 +43,9 @@ impl<
       + Mul<f64, Output = ValueType>,
   > KeyFrame<ValueType>
 {
-  /** Simply passes the data to the timing function involved. Does not do bounding. */
+  /**
+  Simply passes the data to the timing function involved. Does not do bounding.
+  */
   pub fn raw_value_at(
     from: &KeyFrame<ValueType>,
     to: &KeyFrame<ValueType>,
@@ -48,3 +65,95 @@ impl<
     }
   }
 }
+
+#[derive(Clone)]
+pub struct AnimationTrack<ValueType> {
+  pub keyframes: Vec<KeyFrame<ValueType>>,
+  pub loop_count: u32,
+}
+impl<ValueType: Copy> AnimationTrack<ValueType> {
+  fn get_sorted_keyframes(&self) -> Vec<KeyFrame<ValueType>> {
+    let mut kf = self.keyframes.clone();
+    kf.sort_by(|a, b| a.time.total_cmp(&b.time));
+    kf
+  }
+  fn get_first_last(&self) -> Option<(KeyFrame<ValueType>, KeyFrame<ValueType>)> {
+    let okf = self.get_sorted_keyframes();
+    if okf.len() == 0 {
+      None
+    } else {
+      Some((*okf.first().unwrap(), *okf.last().unwrap()))
+    }
+  }
+  fn length(fl: (KeyFrame<ValueType>, KeyFrame<ValueType>)) -> f64 {
+    fl.1.time - fl.0.time
+  }
+}
+impl<
+    ValueType: PartialOrd
+      + Copy
+      + Add<Output = ValueType>
+      + Sub<Output = ValueType>
+      + Mul<f64, Output = ValueType>,
+  > AnimationTrack<ValueType>
+{
+  /** Get the 2 keyframes surrounding the current position in time. */
+  fn get_current_keyframes(
+    &self,
+    // We have the user pass this, as to prevent needing to constantly re-calculate it.
+    sorted_keyframes: Vec<KeyFrame<ValueType>>,
+    time: f64,
+  ) -> Option<(KeyFrame<ValueType>, KeyFrame<ValueType>)> {
+    // TODO: maybe refactor the internals of this to be faster
+    let idx = {
+      let mut idx = 0;
+      let mut found = false;
+      for f in &sorted_keyframes {
+        if f.time > time {
+          found = true;
+          break;
+        } else {
+          idx += 1;
+        }
+      }
+      if found {
+        Some(idx)
+      } else {
+        None
+      }
+    };
+    match idx {
+      None => None,
+      Some(idx) => {
+        // If it's the last item, we don't have a 2nd
+        if idx + 1 == sorted_keyframes.len() {
+          None
+        } else {
+          Some((
+            *sorted_keyframes.index(idx),
+            *sorted_keyframes.index(idx + 1),
+          ))
+        }
+      }
+    }
+  }
+  /** Gets the current value */
+  pub fn get_current_value(
+    &self,
+    // We have the user pass this, as to prevent needing to constantly re-calculate it.
+    sorted_keyframes: Vec<KeyFrame<ValueType>>,
+    time: f64,
+    timing_function: TimingFunction,
+  ) -> Option<ValueType> {
+    let frames = self.get_current_keyframes(sorted_keyframes, time);
+    match frames {
+      Some(frames) => Some(KeyFrame::raw_value_at(
+        &frames.0,
+        &frames.1,
+        time,
+        timing_function,
+      )),
+      None => None,
+    }
+  }
+}
diff --git a/src/main.rs b/src/main.rs
index f9c52f9..c7a7606 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -27,7 +27,6 @@ pub fn main() {
   canvas.present();
   let mut event_pump = sdl_context.event_pump().unwrap();
 
-  // amount to incr sin_offset by per frame
   let start_time = SystemTime::now();
   'running: loop {
     let time = SystemTime::now()