Auto commit

src/lib.rs

@@ -35,9 +35,30 @@ fn normalize(v1: &Vector) -> Vector {
         y: v1.y / calculate_norm(v1),
     }
 }
+fn fade(x: f32) -> f32 {
+    // This is a mathematic equation, it take a value and return the result of the value by that
+    // equation. That equation if derivate should be easy when close to 0 and 1 and hard in the
+    // middle. Take a f32 value return f32.Both value are between 0 and 1
+    6_f32 * x.powi(5) - 15_f32 * x.powi(4) + 10_f32 * x.powi(3)
+}
+/// Linearly interpolates between two scalar values.
+///
+/// # Parameters
+/// - `a`: start value (when `t = 0.0`)
+/// - `b`: end value   (when `t = 1.0`)
+/// - `t`: interpolation factor in `[0.0, 1.0]`
+///
+/// # Returns
+/// A value on the line from `a` to `b`:
+/// - if `t = 0.0`, yields `a`  
+/// - if `t = 1.0`, yields `b`  
+/// - otherwise `a + t * (b - a)`
+fn linear_interpolation(a: f32, b: f32, t: f32) -> f32 {
+    a + t * (b - a)
+}
 #[cfg(test)]
 mod tests {
-    use crate::{Vector, calculate_norm, dot_product, normalize};
+    use crate::{Vector, calculate_norm, dot_product, linear_interpolation, normalize};
     #[test]
     fn test_dot_product() {
         assert_eq!(
@@ -67,4 +88,10 @@ mod tests {
         let v1 = Vector { x: 0.5, y: 0.5 };
         assert_eq!(calculate_norm(&normalize(&v1)).round(), 1_f32);
     }
+    //fn test_fade() {todo!()}
+    #[test]
+    fn test_linear_interpolation() {
+        assert_eq!(linear_interpolation(0.0, 10.0, 0.25), 2.5);
+        assert_eq!(linear_interpolation(5.0, 15.0, 0.75), 12.5);
+    }
 }