Add animation

src/animation/circle.rs

@@ -0,0 +1,51 @@
+use crate::animation::Animation;
+use crate::vec::Vector;
+
+const THICKNESS: f32 = 0.2;
+const FINAL_RADIUS: f32 = 1.0 + THICKNESS * 2.0;
+
+pub struct CircleAnimation {
+    center: Vector,
+    thickness: f32,
+    final_radius: f32,
+}
+
+impl CircleAnimation {
+    pub fn new(size: Vector) -> Self {
+        let center = size.center();
+        let distance = center.length();
+
+        Self {
+            center,
+            thickness: distance * THICKNESS,
+            final_radius: distance * FINAL_RADIUS,
+        }
+    }
+}
+
+impl Animation for CircleAnimation {
+    fn sample(&self, step: f32, pos: Vector) -> f32 {
+        let radius = self.final_radius * step - self.thickness;
+        let distance = (pos - self.center).length();
+
+        (distance - radius) / self.thickness
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn sample() {
+        let anim = CircleAnimation::new(Vector::new(10.0, 20.0));
+
+        let sample_1 = anim.sample(0.5, Vector::new(17.0, 5.0));
+        let sample_2 = anim.sample(0.8, Vector::new(11.0, 8.0));
+        let sample_3 = anim.sample(0.2, Vector::new(7.0, 10.0));
+
+        assert!(3.3 < sample_1 && sample_1 < 3.4);
+        assert!(-1.8 < sample_2 && sample_2 < -1.7);
+        assert!(0.4 < sample_3 && sample_3 < 0.5);
+    }
+}

src/animation/mod.rs

@@ -0,0 +1,7 @@
+mod circle;
+
+use crate::vec::Vector;
+
+pub trait Animation {
+    fn sample(&self, step: f32, pos: Vector) -> f32;
+}

src/main.rs

@@ -8,6 +8,7 @@ mod fill;
 mod vec;
 mod array;
 mod surface;
+mod animation;
 
 #[derive(Parser)]
 #[clap(author = "Rico Riedel", version = "0.1.0", about = "Wipe your terminal with a random animation.")]

src/vec.rs

@@ -1,3 +1,5 @@
+use std::ops::Sub;
+
 /// A vector with a x and y axis.
 #[derive(Copy, Clone)]
 pub struct Vector {
@@ -12,6 +14,14 @@ impl Vector {
         Self { x, y }
     }
 
+    pub fn center(self) -> Self {
+        Self::new(self.x / 2.0, self.y / 2.0)
+    }
+
+    pub fn length(self) -> f32 {
+        (self.x * self.x + self.y * self.y).sqrt()
+    }
+
     /// Creates a vector with the on screen coordinates based on the terminal coordinates.
     /// # Arguments
     /// * `x`: The x axis of the terminal character.
@@ -21,6 +31,14 @@ impl Vector {
     }
 }
 
+impl Sub for Vector {
+    type Output = Vector;
+
+    fn sub(self, rhs: Self) -> Self::Output {
+        Vector::new(self.x - rhs.x, self.y - rhs.y)
+    }
+}
+
 #[cfg(test)]
 mod test {
     use super::*;