use nalgebra::Vector3;

/// A normalized parametric Ray of the form (origin + direction * time)
///
/// That means at any time t: f64, the point represented by origin + direction *
/// time occurs on the ray.
#[derive(Debug)]
pub struct Ray {
  pub origin: Vector3<f64>,
  pub direction: Vector3<f64>,
}

impl Ray {
  /// Construct a ray from endpoints
  pub fn from_endpoints(start: Vector3<f64>, end: Vector3<f64>) -> Self {
    let delta = (end - start).normalize();
    Ray {
      origin: start,
      direction: delta,
    }
  }

  /// Evaluate the ray at a certain point in time, yielding a point
  pub fn eval(&self, time: f64) -> Vector3<f64> {
    self.origin + self.direction * time
  }
}