From 6a7a3c777490ab253a639f5b523551816a5255e9 Mon Sep 17 00:00:00 2001
From: bijan2005 <rhombusesarekites>
Date: Mon, 30 Nov 2020 09:00:35 -0500
Subject: [PATCH] Plane-ray intersection test

---
 README.md           | 4 ++--
 src/object.rs       | 1 +
 src/object/plane.rs | 9 ++++++++-
 3 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/README.md b/README.md
index f5777a3..c019091 100644
--- a/README.md
+++ b/README.md
@@ -15,8 +15,8 @@ This list may be changed or extended in the future.
   - [x] Sphere normal generation
   - [x] Color mapping on spheres
 - [ ] Plane objects
-  - [ ] Plane struct
-  - [ ] Plane intersection test
+  - [x] Plane struct
+  - [x] Plane intersection test
   - [ ] Color mapping on planes
 - [ ] Triangle objects
   - [ ] Triangle struct
diff --git a/src/object.rs b/src/object.rs
index cbd6b0e..9be2ca6 100644
--- a/src/object.rs
+++ b/src/object.rs
@@ -1,5 +1,6 @@
 
 mod sphere; pub use sphere::*;
+mod plane; pub use plane::*;
 mod triangle; pub use triangle::*;
 
 use na::*;
diff --git a/src/object/plane.rs b/src/object/plane.rs
index 59ffae2..8e50e51 100644
--- a/src/object/plane.rs
+++ b/src/object/plane.rs
@@ -27,7 +27,14 @@ impl Plane {
         { Plane::new(center, normal, move |_, _| color) }
 
     pub fn intersect(&self, ray: Ray) -> Option<f32> {
-        unimplemented!()
+
+        let d = self.normal.dot(&ray.direction);
+        if d < 1e-6 { return None; }
+
+        let t = (self.center - ray.origin).dot(&*self.normal) / d;
+
+        if t >= 0.0 { Some(t) }
+        else { None }
     }
 
     pub fn getcolor(&self, point: Point3<f32>) -> Color {