library: light: add AmbientLight implementation

src/light/ambient_light.rs

@@ -0,0 +1,41 @@
+use super::super::core::LinearColor;
+use super::super::Point;
+use super::Light;
+
+/// Represent an ambient lighting which is equal in all points of the scene.
+#[derive(Debug, PartialEq)]
+pub struct AmbientLight {
+    color: LinearColor,
+}
+
+impl AmbientLight {
+    pub fn new(color: LinearColor) -> Self {
+        AmbientLight { color }
+    }
+}
+
+impl Light for AmbientLight {
+    fn illumination(&self, _: &Point) -> LinearColor {
+        self.color.clone()
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn new_works() {
+        let color = LinearColor::new(1., 1., 1.);
+        let light = AmbientLight::new(color.clone());
+        let res = AmbientLight { color };
+        assert_eq!(light, res)
+    }
+
+    #[test]
+    fn illumination_is_correct() {
+        let light = AmbientLight::new(LinearColor::new(1., 1., 1.));
+        let lum = light.illumination(&Point::new(1., 1., 1.));
+        assert_eq!(lum, LinearColor::new(1., 1., 1.))
+    }
+}

src/light/mod.rs

@@ -13,6 +13,9 @@ pub trait SpatialLight: Light {
     fn to_source(&self, origin: &Point) -> (Vector, f32);
 }
 
+pub mod ambient_light;
+pub use ambient_light::*;
+
 pub mod directional_light;
 pub use directional_light::*;