1 files changed, 69 insertions, 0 deletions
diff --git a/src/world/instancing.rs b/src/world/instancing.rs
new file mode 100644
index 0000000..0a92746
--- /dev/null
+++ b/src/world/instancing.rs
@@ -0,0 +1,69 @@
+use crate::Float;
+use crate::core::{Ray, Vector3f, Bound3f};
+use crate::world::{Hittable, DynHittable, Intersection};
+
+pub struct Instance {
+    inner: DynHittable,
+    translate: Vector3f,
+}
+
+pub trait Instancable: Into<DynHittable> {
+    fn translate(self, x: Float, y: Float, z: Float) -> Instance {
+        self.translate_vec(Vector3f::new_xyz(x, y, z))
+    }
+
+    fn translate_vec(self, offset: Vector3f) -> Instance {
+        Instance::new_translate(self.into(), offset)
+    }
+}
+
+impl Instance {
+    pub fn new_translate(inner: DynHittable, offset: Vector3f) -> Self {
+        Self {
+            inner,
+            translate: offset,
+        }
+    }
+}
+
+impl Hittable for Instance {
+    fn intersect(&self, ray: &Ray) -> Option<Intersection> {
+        let ray = Ray::new(ray.origin - self.translate, ray.direction);
+
+        self.inner.intersect(&ray).map(|mut int| {
+            int.p += &self.translate;
+            int
+        })
+    }
+
+    fn bounding_box(&self) -> Bound3f {
+        self.inner.bounding_box().offset(self.translate)
+    }
+}
+
+impl Into<DynHittable> for Instance {
+    fn into(self) -> DynHittable {
+        DynHittable::new(Box::new(self))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::world::shapes::Sphere;
+
+    #[test]
+    fn sphere_translation() {
+        //let sph = Sphere::new(2.0).translate(2.0, 3.0, 4.0);
+        let sph = Sphere::new(2.0).translate(2.0, 3.0, 4.0);
+
+        let ray = Ray {
+            origin: Vector3f::new_xyz(1.0, 0.0, 0.0),
+            direction: Vector3f::new_xyz(0.0, 1.0, 1.5).norm(),
+        };
+
+        let dist = sph.intersect(&ray).unwrap();
+        println!("hey {}", dist.t);
+        assert!((dist.t - 3.28).abs() < 0.01);
+    }
+}