3 files changed, 57 insertions, 1 deletions
diff --git a/src/material/diffuse_light.rs b/src/material/diffuse_light.rs
new file mode 100644
index 0000000..fe462a8
--- /dev/null
+++ b/src/material/diffuse_light.rs
@@ -0,0 +1,27 @@
+use super::Material;
+use crate::core::{Ray, Spectrum};
+use crate::Float;
+
+pub struct DiffuseLight {
+    color: Spectrum,
+}
+
+impl DiffuseLight {
+    pub fn new(c: Spectrum) -> Self {
+        Self {
+            color: c,
+        }
+    }
+
+    pub fn new_white(s: Float) -> Self {
+        Self {
+            color: Spectrum::new_rgb(s, s, s),
+        }
+    }
+}
+
+impl Material for DiffuseLight {
+    fn emitted(&self, _: &Ray) -> Option<Spectrum> {
+        Some(self.color)
+    }
+}
diff --git a/src/material/mod.rs b/src/material/mod.rs
index 7f920e2..3e92bf6 100644
--- a/src/material/mod.rs
+++ b/src/material/mod.rs
@@ -4,10 +4,20 @@ use crate::sample::Sampler;
 
 mod lambertian;
 mod reflectant;
+mod diffuse_light;
+mod sky_light;
 
 pub use lambertian::Lambertian;
 pub use reflectant::Reflectant;
+pub use diffuse_light::DiffuseLight;
+pub use sky_light::SkyLight;
 
 pub trait Material: Sync + Send {
-    fn scatter(&self, ray: &Ray, i: &Intersection, sampler: &mut dyn Sampler) -> Option<(Spectrum, Ray)>;
+    fn scatter(&self, _: &Ray, _: &Intersection, _: &mut dyn Sampler) -> Option<(Spectrum, Ray)> {
+        None
+    }
+
+    fn emitted(&self, _: &Ray) -> Option<Spectrum> {
+        None
+    }
 }
diff --git a/src/material/sky_light.rs b/src/material/sky_light.rs
new file mode 100644
index 0000000..e499b6e
--- /dev/null
+++ b/src/material/sky_light.rs
@@ -0,0 +1,19 @@
+use super::Material;
+use crate::core::{Ray, Spectrum};
+
+pub struct SkyLight {
+}
+
+impl SkyLight {
+    pub fn new() -> Self {
+        Self {}
+    }
+}
+
+impl Material for SkyLight {
+    fn emitted(&self, ray: &Ray) -> Option<Spectrum> {
+        let t = (ray.direction.norm().y + 1.0) * 0.5;
+
+        Some(Spectrum::new_rgb(1.0, 1.0, 1.0) * (1.0-t) + Spectrum::new_rgb(0.5, 0.7, 1.0) * t)
+    }
+}