From 6843cbaeaca73ecdbebe852b7e7899ce48f8a83c Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Sun, 19 May 2013 21:25:47 +0300
Subject: [PATCH] Use a cached inverse transformation in TransformedShape

---
 source/geometry/transformedshape.h | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/source/geometry/transformedshape.h b/source/geometry/transformedshape.h
index 10789ed..2168126 100644
--- a/source/geometry/transformedshape.h
+++ b/source/geometry/transformedshape.h
@@ -14,6 +14,7 @@ class TransformedShape: public Shape<T, D>
 private:
 	Shape<T, D> *shape;
 	AffineTransformation<T, D> transformation;
+	AffineTransformation<T, D> inverse_trans;
 
 public:
 	TransformedShape(const Shape<T, D> &, const AffineTransformation<T, D> &);
@@ -33,13 +34,15 @@ public:
 template<typename T, unsigned D>
 inline TransformedShape<T, D>::TransformedShape(const Shape<T, D> &s, const AffineTransformation<T, D> &t):
 	shape(s.clone()),
-	transformation(t)
+	transformation(t),
+	inverse_trans(invert(t))
 { }
 
 template<typename T, unsigned D>
 inline TransformedShape<T, D>::TransformedShape(const TransformedShape &other):
 	shape(other.shape->clone()),
-	transformation(other.transformation)
+	transformation(other.transformation),
+	inverse_trans(other.inverse_trans)
 { }
 
 template<typename T, unsigned D>
@@ -48,6 +51,7 @@ inline TransformedShape<T, D> &TransformedShape<T, D>::operator=(const Transform
 	delete shape;
 	shape = other.shape->clone();
 	transformation = other.transformation;
+	inverse_trans = other.inverse_trans;
 }
 
 template<typename T, unsigned D>
@@ -72,11 +76,9 @@ inline HyperBox<T, D> TransformedShape<T, D>::get_axis_aligned_bounding_box() co
 template<typename T, unsigned D>
 inline bool TransformedShape<T, D>::check_intersection(const Ray<T, D> &ray) const
 {
-	// TODO cache the inverse transformation for performance
-	LinAl::SquareMatrix<T, D+1> inverse_trans = LinAl::invert(transformation.get_matrix());
-	Ray<T, D> trans_ray(reduce_vector(inverse_trans*augment_vector(ray.get_start(), T(1))),
-		reduce_vector(inverse_trans*augment_vector(ray.get_direction(), T(0))));
-	return shape->check_intersection(trans_ray);
+	Ray<T, D> local_ray(inverse_trans.transform(ray.get_start()),
+		inverse_trans.transform_linear(ray.get_direction()));
+	return shape->check_intersection(local_ray);
 }
 
 } // namespace Geometry
-- 
2.43.0