From d0d667d6d2b3833ad72fee93776d55d07141b58f Mon Sep 17 00:00:00 2001
From: Eryn Wells <eryn@erynwells.me>
Date: Sat, 9 Aug 2014 09:59:00 -0700
Subject: [PATCH] Object::Intersect

A new intersect method that converts to object space before doing the intersection. Now all objects are at their own origin!
---
 src/object.cc | 34 ++++++++++++++++++++++++++++++++++
 src/object.h  | 17 ++++++++++++++++-
 2 files changed, 50 insertions(+), 1 deletion(-)

diff --git a/src/object.cc b/src/object.cc
index 22a173f..3b6ce8c 100644
--- a/src/object.cc
+++ b/src/object.cc
@@ -22,6 +22,9 @@ namespace charles {
 
 #pragma mark - Objects
 
+/*
+ * charles::Object::Object --
+ */
 Object::Object(const Vector4& origin)
     : mTranslation(basics::TranslationMatrix(origin.X(), origin.Y(), origin.Z())),
       mMaterial()
@@ -49,6 +52,37 @@ Object::SetMaterial(const Material& material)
 }
 
 
+/*
+ * charles::Object::Intersect --
+ */
+bool
+Object::Intersect(const basics::Ray& ray,
+                  TVector& t,
+                  Stats& stats)
+    const
+{
+    /* TODO: Remove basics:: when the old Ray class goes away. */
+    basics::Ray objRay = ToObjectSpace(ray);
+    return DoIntersect(objRay, t, stats);
+}
+
+
+/*
+ * charles::Object::ToObjectSpace --
+ */
+/* TODO: Remove basics:: when the old Ray class goes away. */
+basics::Ray
+Object::ToObjectSpace(const basics::Ray& ray)
+    const
+{
+    /* TODO: Remove basics:: when the old Ray class goes away. */
+    basics::Ray objRay(ray);
+    objRay.origin = mTranslation * objRay.origin;
+    objRay.direction = mTranslation * objRay.direction;
+    return objRay;
+}
+
+
 void
 Object::Write(std::ostream& ost)
     const
diff --git a/src/object.h b/src/object.h
index c51f908..c0d8071 100644
--- a/src/object.h
+++ b/src/object.h
@@ -37,7 +37,15 @@ struct Object
     void SetMaterial(const Material& material);
 
     /**
-     * Determines if the given ray intersects with this object. All intersection
+     * Determine if the given ray intersects with this object. Converts the
+     * ray's origin and direction to object space before calling the protected
+     * Object::DoIntersect method. All intersection t values are returned in the
+     * `t` argument, in ascending order.
+     */
+    bool Intersect(const basics::Ray& ray, TVector& t, Stats& stats) const;
+
+    /**
+     * Determine if the given ray intersects with this object. All intersection
      * t values are returned in the `t` argument, in increasing order.
      *
      * @param [in]  ray     The ray to test for intersection
@@ -50,7 +58,14 @@ struct Object
 
     virtual void Write(std::ostream& ost) const;
 
+protected:
+    virtual bool DoIntersect(const basics::Ray& ray, TVector& t, Stats& stats) const;
+
 private:
+    basics::Ray ToObjectSpace(const basics::Ray& ray) const;
+
+    /** A translation matrix from global coordinates to this object's space. */
+    basics::Matrix4 mTranslation;
 
     /** This object's material, surface properties, etc. */
     Material mMaterial;