Add the `transform` methods as inherent methods on geometric types

This adds `transform_point`, `transform_vector`,
`inverse_transform_point` and `inverse_transform_vector` as inherent
methods on the applicable geometric transformation structures, such
that they can be used without the need to import the `Transformation`
and `ProjectiveTransformation` traits from `alga`.

src/geometry/isometry.rs

@@ -17,7 +17,7 @@ use alga::linear::Rotation;
 use base::allocator::Allocator;
 use base::dimension::{DimName, DimNameAdd, DimNameSum, U1};
 use base::storage::Owned;
-use base::{DefaultAllocator, MatrixN};
+use base::{DefaultAllocator, MatrixN, VectorN};
 use geometry::{Point, Translation};
 
 /// A direct isometry, i.e., a rotation followed by a translation, aka. a rigid-body motion, aka. an element of a Special Euclidean (SE) group.
@@ -254,6 +254,93 @@ where DefaultAllocator: Allocator<N, D>
     pub fn append_rotation_wrt_center_mut(&mut self, r: &R) {
         self.rotation = self.rotation.append_rotation(r);
     }
+
+    /// Transform the given point by this isometry.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// # #[macro_use] extern crate approx;
+    /// # use std::f32;
+    /// # use nalgebra::{Isometry3, Translation3, UnitQuaternion, Vector3, Point3};
+    /// let tra = Translation3::new(0.0, 0.0, 3.0);
+    /// let rot = UnitQuaternion::from_scaled_axis(Vector3::y() * f32::consts::FRAC_PI_2);
+    /// let iso = Isometry3::from_parts(tra, rot);
+    ///
+    /// let transformed_point = iso.transform_point(&Point3::new(1.0, 2.0, 3.0));
+    /// assert_relative_eq!(transformed_point, Point3::new(3.0, 2.0, 2.0), epsilon = 1.0e-6);
+    /// ```
+    #[inline]
+    pub fn transform_point(&self, pt: &Point<N, D>) -> Point<N, D> {
+        self * pt
+    }
+
+    /// Transform the given vector by this isometry, ignoring the translation
+    /// component of the isometry.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// # #[macro_use] extern crate approx;
+    /// # use std::f32;
+    /// # use nalgebra::{Isometry3, Translation3, UnitQuaternion, Vector3};
+    /// let tra = Translation3::new(0.0, 0.0, 3.0);
+    /// let rot = UnitQuaternion::from_scaled_axis(Vector3::y() * f32::consts::FRAC_PI_2);
+    /// let iso = Isometry3::from_parts(tra, rot);
+    ///
+    /// let transformed_point = iso.transform_vector(&Vector3::new(1.0, 2.0, 3.0));
+    /// assert_relative_eq!(transformed_point, Vector3::new(3.0, 2.0, -1.0), epsilon = 1.0e-6);
+    /// ```
+    #[inline]
+    pub fn transform_vector(&self, v: &VectorN<N, D>) -> VectorN<N, D> {
+        self * v
+    }
+
+    /// Transform the given point by the inverse of this isometry. This may be
+    /// less expensive than computing the entire isometry inverse and then
+    /// transforming the point.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// # #[macro_use] extern crate approx;
+    /// # use std::f32;
+    /// # use nalgebra::{Isometry3, Translation3, UnitQuaternion, Vector3, Point3};
+    /// let tra = Translation3::new(0.0, 0.0, 3.0);
+    /// let rot = UnitQuaternion::from_scaled_axis(Vector3::y() * f32::consts::FRAC_PI_2);
+    /// let iso = Isometry3::from_parts(tra, rot);
+    ///
+    /// let transformed_point = iso.inverse_transform_point(&Point3::new(1.0, 2.0, 3.0));
+    /// assert_relative_eq!(transformed_point, Point3::new(0.0, 2.0, 1.0), epsilon = 1.0e-6);
+    /// ```
+    #[inline]
+    pub fn inverse_transform_point(&self, pt: &Point<N, D>) -> Point<N, D> {
+        self.rotation
+            .inverse_transform_point(&(pt - &self.translation.vector))
+    }
+
+    /// Transform the given vector by the inverse of this isometry, ignoring the
+    /// translation component of the isometry. This may be
+    /// less expensive than computing the entire isometry inverse and then
+    /// transforming the point.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// # #[macro_use] extern crate approx;
+    /// # use std::f32;
+    /// # use nalgebra::{Isometry3, Translation3, UnitQuaternion, Vector3};
+    /// let tra = Translation3::new(0.0, 0.0, 3.0);
+    /// let rot = UnitQuaternion::from_scaled_axis(Vector3::y() * f32::consts::FRAC_PI_2);
+    /// let iso = Isometry3::from_parts(tra, rot);
+    ///
+    /// let transformed_point = iso.inverse_transform_vector(&Vector3::new(1.0, 2.0, 3.0));
+    /// assert_relative_eq!(transformed_point, Vector3::new(-3.0, 2.0, 1.0), epsilon = 1.0e-6);
+    /// ```
+    #[inline]
+    pub fn inverse_transform_vector(&self, v: &VectorN<N, D>) -> VectorN<N, D> {
+        self.rotation.inverse_transform_vector(v)
+    }
 }
 
 // NOTE: we don't require `R: Rotation<...>` here because this is not useful for the implementation

src/geometry/isometry_alga.rs

@@ -85,12 +85,12 @@ where
 {
     #[inline]
     fn transform_point(&self, pt: &Point<N, D>) -> Point<N, D> {
-        self * pt
+        self.transform_point(pt)
     }
 
     #[inline]
     fn transform_vector(&self, v: &VectorN<N, D>) -> VectorN<N, D> {
-        self * v
+        self.transform_vector(v)
     }
 }
 
@@ -101,13 +101,12 @@ where
 {
     #[inline]
     fn inverse_transform_point(&self, pt: &Point<N, D>) -> Point<N, D> {
-        self.rotation
+        self.inverse_transform_point(pt)
-            .inverse_transform_point(&(pt - &self.translation.vector))
     }
 
     #[inline]
     fn inverse_transform_vector(&self, v: &VectorN<N, D>) -> VectorN<N, D> {
-        self.rotation.inverse_transform_vector(v)
+        self.inverse_transform_vector(v)
     }
 }
 

src/geometry/quaternion.rs

@@ -19,7 +19,7 @@ use base::dimension::{U1, U3, U4};
 use base::storage::{CStride, RStride};
 use base::{Matrix3, MatrixN, MatrixSlice, MatrixSliceMut, Unit, Vector3, Vector4};
 
-use geometry::Rotation;
+use geometry::{Point3, Rotation};
 
 /// A quaternion. See the type alias `UnitQuaternion = Unit<Quaternion>` for a quaternion
 /// that may be used as a rotation.
@@ -1005,6 +1005,84 @@ impl<N: Real> UnitQuaternion<N> {
     pub fn to_homogeneous(&self) -> MatrixN<N, U4> {
         self.to_rotation_matrix().to_homogeneous()
     }
+
+    /// Rotate a point by this unit quaternion.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// # #[macro_use] extern crate approx;
+    /// # use std::f32;
+    /// # use nalgebra::{UnitQuaternion, Vector3, Point3};
+    /// let rot = UnitQuaternion::from_axis_angle(&Vector3::y_axis(), f32::consts::FRAC_PI_2);
+    /// let transformed_point = rot.transform_point(&Point3::new(1.0, 2.0, 3.0));
+    ///
+    /// assert_relative_eq!(transformed_point, Point3::new(3.0, 2.0, -1.0), epsilon = 1.0e-6);
+    /// ```
+    #[inline]
+    pub fn transform_point(&self, pt: &Point3<N>) -> Point3<N> {
+        self * pt
+    }
+
+    /// Rotate a vector by this unit quaternion.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// # #[macro_use] extern crate approx;
+    /// # use std::f32;
+    /// # use nalgebra::{UnitQuaternion, Vector3};
+    /// let rot = UnitQuaternion::from_axis_angle(&Vector3::y_axis(), f32::consts::FRAC_PI_2);
+    /// let transformed_vector = rot.transform_vector(&Vector3::new(1.0, 2.0, 3.0));
+    ///
+    /// assert_relative_eq!(transformed_vector, Vector3::new(3.0, 2.0, -1.0), epsilon = 1.0e-6);
+    /// ```
+    #[inline]
+    pub fn transform_vector(&self, v: &Vector3<N>) -> Vector3<N> {
+        self * v
+    }
+
+    /// Rotate a point by the inverse of this unit quaternion. This may be
+    /// cheaper than inverting the unit quaternion and transforming the
+    /// point.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// # #[macro_use] extern crate approx;
+    /// # use std::f32;
+    /// # use nalgebra::{UnitQuaternion, Vector3, Point3};
+    /// let rot = UnitQuaternion::from_axis_angle(&Vector3::y_axis(), f32::consts::FRAC_PI_2);
+    /// let transformed_point = rot.inverse_transform_point(&Point3::new(1.0, 2.0, 3.0));
+    ///
+    /// assert_relative_eq!(transformed_point, Point3::new(-3.0, 2.0, 1.0), epsilon = 1.0e-6);
+    /// ```
+    #[inline]
+    pub fn inverse_transform_point(&self, pt: &Point3<N>) -> Point3<N> {
+        // FIXME: would it be useful performancewise not to call inverse explicitly (i-e. implement
+        // the inverse transformation explicitly here) ?
+        self.inverse() * pt
+    }
+
+    /// Rotate a vector by the inverse of this unit quaternion. This may be
+    /// cheaper than inverting the unit quaternion and transforming the
+    /// vector.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// # #[macro_use] extern crate approx;
+    /// # use std::f32;
+    /// # use nalgebra::{UnitQuaternion, Vector3};
+    /// let rot = UnitQuaternion::from_axis_angle(&Vector3::y_axis(), f32::consts::FRAC_PI_2);
+    /// let transformed_vector = rot.inverse_transform_vector(&Vector3::new(1.0, 2.0, 3.0));
+    ///
+    /// assert_relative_eq!(transformed_vector, Vector3::new(-3.0, 2.0, 1.0), epsilon = 1.0e-6);
+    /// ```
+    #[inline]
+    pub fn inverse_transform_vector(&self, v: &Vector3<N>) -> Vector3<N> {
+        self.inverse() * v
+    }
 }
 
 impl<N: Real + fmt::Display> fmt::Display for UnitQuaternion<N> {

src/geometry/quaternion_alga.rs

@@ -197,26 +197,24 @@ impl_structures!(
 impl<N: Real> Transformation<Point3<N>> for UnitQuaternion<N> {
     #[inline]
     fn transform_point(&self, pt: &Point3<N>) -> Point3<N> {
-        self * pt
+        self.transform_point(pt)
     }
 
     #[inline]
     fn transform_vector(&self, v: &Vector3<N>) -> Vector3<N> {
-        self * v
+        self.transform_vector(v)
     }
 }
 
 impl<N: Real> ProjectiveTransformation<Point3<N>> for UnitQuaternion<N> {
     #[inline]
     fn inverse_transform_point(&self, pt: &Point3<N>) -> Point3<N> {
-        // FIXME: would it be useful performancewise not to call inverse explicitly (i-e. implement
+        self.inverse_transform_point(pt)
-        // the inverse transformation explicitly here) ?
-        self.inverse() * pt
     }
 
     #[inline]
     fn inverse_transform_vector(&self, v: &Vector3<N>) -> Vector3<N> {
-        self.inverse() * v
+        self.inverse_transform_vector(v)
     }
 }
 

src/geometry/rotation.rs

@@ -18,7 +18,9 @@ use alga::general::Real;
 
 use base::allocator::Allocator;
 use base::dimension::{DimName, DimNameAdd, DimNameSum, U1};
-use base::{DefaultAllocator, MatrixN, Scalar};
+use base::{DefaultAllocator, MatrixN, Scalar, VectorN};
+
+use geometry::Point;
 
 /// A rotation matrix.
 #[repr(C)]
@@ -351,6 +353,82 @@ where DefaultAllocator: Allocator<N, D, D>
     }
 }
 
+impl<N: Real, D: DimName> Rotation<N, D>
+where DefaultAllocator: Allocator<N, D, D> + Allocator<N, D>
+{
+    /// Rotate the given point.
+    ///
+    /// # Example
+    /// ```
+    /// # #[macro_use] extern crate approx;
+    /// # use std::f32;
+    /// # use nalgebra::{Point3, Rotation2, Rotation3, UnitQuaternion, Vector3};
+    /// let rot = Rotation3::new(Vector3::y() * f32::consts::FRAC_PI_2);
+    /// let transformed_point = rot.transform_point(&Point3::new(1.0, 2.0, 3.0));
+    ///
+    /// assert_relative_eq!(transformed_point, Point3::new(3.0, 2.0, -1.0), epsilon = 1.0e-6);
+    /// ```
+    #[inline]
+    pub fn transform_point(&self, pt: &Point<N, D>) -> Point<N, D> {
+        self * pt
+    }
+
+    /// Rotate the given vector.
+    ///
+    /// # Example
+    /// ```
+    /// # #[macro_use] extern crate approx;
+    /// # use std::f32;
+    /// # use nalgebra::{Rotation2, Rotation3, UnitQuaternion, Vector3};
+    /// let rot = Rotation3::new(Vector3::y() * f32::consts::FRAC_PI_2);
+    /// let transformed_vector = rot.transform_vector(&Vector3::new(1.0, 2.0, 3.0));
+    ///
+    /// assert_relative_eq!(transformed_vector, Vector3::new(3.0, 2.0, -1.0), epsilon = 1.0e-6);
+    /// ```
+    #[inline]
+    pub fn transform_vector(&self, v: &VectorN<N, D>) -> VectorN<N, D> {
+        self * v
+    }
+
+    /// Rotate the given point by the inverse of this rotation. This may be
+    /// cheaper than inverting the rotation and then transforming the given
+    /// point.
+    ///
+    /// # Example
+    /// ```
+    /// # #[macro_use] extern crate approx;
+    /// # use std::f32;
+    /// # use nalgebra::{Point3, Rotation2, Rotation3, UnitQuaternion, Vector3};
+    /// let rot = Rotation3::new(Vector3::y() * f32::consts::FRAC_PI_2);
+    /// let transformed_point = rot.inverse_transform_point(&Point3::new(1.0, 2.0, 3.0));
+    ///
+    /// assert_relative_eq!(transformed_point, Point3::new(-3.0, 2.0, 1.0), epsilon = 1.0e-6);
+    /// ```
+    #[inline]
+    pub fn inverse_transform_point(&self, pt: &Point<N, D>) -> Point<N, D> {
+        Point::from(self.inverse_transform_vector(&pt.coords))
+    }
+
+    /// Rotate the given vector by the inverse of this rotation. This may be
+    /// cheaper than inverting the rotation and then transforming the given
+    /// vector.
+    ///
+    /// # Example
+    /// ```
+    /// # #[macro_use] extern crate approx;
+    /// # use std::f32;
+    /// # use nalgebra::{Rotation2, Rotation3, UnitQuaternion, Vector3};
+    /// let rot = Rotation3::new(Vector3::y() * f32::consts::FRAC_PI_2);
+    /// let transformed_vector = rot.inverse_transform_vector(&Vector3::new(1.0, 2.0, 3.0));
+    ///
+    /// assert_relative_eq!(transformed_vector, Vector3::new(-3.0, 2.0, 1.0), epsilon = 1.0e-6);
+    /// ```
+    #[inline]
+    pub fn inverse_transform_vector(&self, v: &VectorN<N, D>) -> VectorN<N, D> {
+        self.matrix().tr_mul(v)
+    }
+}
+
 impl<N: Scalar + Eq, D: DimName> Eq for Rotation<N, D> where DefaultAllocator: Allocator<N, D, D> {}
 
 impl<N: Scalar + PartialEq, D: DimName> PartialEq for Rotation<N, D>

src/geometry/rotation_alga.rs

@@ -75,12 +75,12 @@ where DefaultAllocator: Allocator<N, D, D> + Allocator<N, D>
 {
     #[inline]
     fn transform_point(&self, pt: &Point<N, D>) -> Point<N, D> {
-        self * pt
+        self.transform_point(pt)
     }
 
     #[inline]
     fn transform_vector(&self, v: &VectorN<N, D>) -> VectorN<N, D> {
-        self * v
+        self.transform_vector(v)
     }
 }
 
@@ -89,12 +89,12 @@ where DefaultAllocator: Allocator<N, D, D> + Allocator<N, D>
 {
     #[inline]
     fn inverse_transform_point(&self, pt: &Point<N, D>) -> Point<N, D> {
-        Point::from(self.inverse_transform_vector(&pt.coords))
+        self.inverse_transform_point(pt)
     }
 
     #[inline]
     fn inverse_transform_vector(&self, v: &VectorN<N, D>) -> VectorN<N, D> {
-        self.matrix().tr_mul(v)
+        self.inverse_transform_vector(v)
     }
 }
 

src/geometry/similarity.rs

@@ -16,7 +16,7 @@ use alga::linear::Rotation;
 use base::allocator::Allocator;
 use base::dimension::{DimName, DimNameAdd, DimNameSum, U1};
 use base::storage::Owned;
-use base::{DefaultAllocator, MatrixN};
+use base::{DefaultAllocator, MatrixN, VectorN};
 use geometry::{Isometry, Point, Translation};
 
 /// A similarity, i.e., an uniform scaling, followed by a rotation, followed by a translation.
@@ -238,6 +238,83 @@ where
     pub fn append_rotation_wrt_center_mut(&mut self, r: &R) {
         self.isometry.append_rotation_wrt_center_mut(r)
     }
+
+    /// Transform the given point by this similarity.
+    ///
+    /// # Example
+    /// ```
+    /// # #[macro_use] extern crate approx;
+    /// # use std::f32;
+    /// # use nalgebra::{Point3, Similarity3, Vector3};
+    /// let axisangle = Vector3::y() * f32::consts::FRAC_PI_2;
+    /// let translation = Vector3::new(1.0, 2.0, 3.0);
+    /// let sim = Similarity3::new(translation, axisangle, 3.0);
+    /// let transformed_point = sim.transform_point(&Point3::new(4.0, 5.0, 6.0));
+    /// assert_relative_eq!(transformed_point, Point3::new(19.0, 17.0, -9.0), epsilon = 1.0e-5);
+    /// ```
+    #[inline]
+    pub fn transform_point(&self, pt: &Point<N, D>) -> Point<N, D> {
+        self * pt
+    }
+
+    /// Transform the given vector by this similarity, ignoring the translational
+    /// component.
+    ///
+    /// # Example
+    /// ```
+    /// # #[macro_use] extern crate approx;
+    /// # use std::f32;
+    /// # use nalgebra::{Similarity3, Vector3};
+    /// let axisangle = Vector3::y() * f32::consts::FRAC_PI_2;
+    /// let translation = Vector3::new(1.0, 2.0, 3.0);
+    /// let sim = Similarity3::new(translation, axisangle, 3.0);
+    /// let transformed_vector = sim.transform_vector(&Vector3::new(4.0, 5.0, 6.0));
+    /// assert_relative_eq!(transformed_vector, Vector3::new(18.0, 15.0, -12.0), epsilon = 1.0e-5);
+    /// ```
+    #[inline]
+    pub fn transform_vector(&self, v: &VectorN<N, D>) -> VectorN<N, D> {
+        self * v
+    }
+
+    /// Transform the given point by the inverse of this similarity. This may
+    /// be cheaper than inverting the similarity and then transforming the
+    /// given point.
+    ///
+    /// # Example
+    /// ```
+    /// # #[macro_use] extern crate approx;
+    /// # use std::f32;
+    /// # use nalgebra::{Point3, Similarity3, Vector3};
+    /// let axisangle = Vector3::y() * f32::consts::FRAC_PI_2;
+    /// let translation = Vector3::new(1.0, 2.0, 3.0);
+    /// let sim = Similarity3::new(translation, axisangle, 2.0);
+    /// let transformed_point = sim.inverse_transform_point(&Point3::new(4.0, 5.0, 6.0));
+    /// assert_relative_eq!(transformed_point, Point3::new(-1.5, 1.5, 1.5), epsilon = 1.0e-5);
+    /// ```
+    #[inline]
+    pub fn inverse_transform_point(&self, pt: &Point<N, D>) -> Point<N, D> {
+        self.isometry.inverse_transform_point(pt) / self.scaling()
+    }
+
+    /// Transform the given vector by the inverse of this similarity,
+    /// ignoring the translational component. This may be cheaper than
+    /// inverting the similarity and then transforming the given vector.
+    ///
+    /// # Example
+    /// ```
+    /// # #[macro_use] extern crate approx;
+    /// # use std::f32;
+    /// # use nalgebra::{Similarity3, Vector3};
+    /// let axisangle = Vector3::y() * f32::consts::FRAC_PI_2;
+    /// let translation = Vector3::new(1.0, 2.0, 3.0);
+    /// let sim = Similarity3::new(translation, axisangle, 2.0);
+    /// let transformed_vector = sim.inverse_transform_vector(&Vector3::new(4.0, 5.0, 6.0));
+    /// assert_relative_eq!(transformed_vector, Vector3::new(-3.0, 2.5, 2.0), epsilon = 1.0e-5);
+    /// ```
+    #[inline]
+    pub fn inverse_transform_vector(&self, v: &VectorN<N, D>) -> VectorN<N, D> {
+        self.isometry.inverse_transform_vector(v) / self.scaling()
+    }
 }
 
 // NOTE: we don't require `R: Rotation<...>` here because this is not useful for the implementation

src/geometry/similarity_alga.rs

@@ -82,12 +82,12 @@ where
 {
     #[inline]
     fn transform_point(&self, pt: &Point<N, D>) -> Point<N, D> {
-        self * pt
+        self.transform_point(pt)
     }
 
     #[inline]
     fn transform_vector(&self, v: &VectorN<N, D>) -> VectorN<N, D> {
-        self * v
+        self.transform_vector(v)
     }
 }
 
@@ -98,12 +98,12 @@ where
 {
     #[inline]
     fn inverse_transform_point(&self, pt: &Point<N, D>) -> Point<N, D> {
-        self.isometry.inverse_transform_point(pt) / self.scaling()
+        self.inverse_transform_point(pt)
     }
 
     #[inline]
     fn inverse_transform_vector(&self, v: &VectorN<N, D>) -> VectorN<N, D> {
-        self.isometry.inverse_transform_vector(v) / self.scaling()
+        self.inverse_transform_vector(v)
     }
 }
 

src/geometry/transform.rs

@@ -6,12 +6,14 @@ use std::marker::PhantomData;
 #[cfg(feature = "serde-serialize")]
 use serde::{Deserialize, Deserializer, Serialize, Serializer};
 
-use alga::general::Real;
+use alga::general::{Real, TwoSidedInverse};
 
 use base::allocator::Allocator;
 use base::dimension::{DimName, DimNameAdd, DimNameSum, U1};
 use base::storage::Owned;
-use base::{DefaultAllocator, MatrixN};
+use base::{DefaultAllocator, MatrixN, VectorN};
+
+use geometry::Point;
 
 /// Trait implemented by phantom types identifying the projective transformation type.
 ///
@@ -452,6 +454,53 @@ where DefaultAllocator: Allocator<N, DimNameSum<D, U1>, DimNameSum<D, U1>>
     }
 }
 
+impl<N, D: DimNameAdd<U1>, C> Transform<N, D, C>
+where
+    N: Real,
+    C: TCategory,
+    DefaultAllocator: Allocator<N, DimNameSum<D, U1>, DimNameSum<D, U1>>
+        + Allocator<N, DimNameSum<D, U1>>
+        + Allocator<N, D, D>
+        + Allocator<N, D>,
+{
+    /// Transform the given point by this transformation.
+    #[inline]
+    pub fn transform_point(&self, pt: &Point<N, D>) -> Point<N, D> {
+        self * pt
+    }
+
+    /// Transform the given vector by this transformation, ignoring the
+    /// translational component of the transformation.
+    #[inline]
+    pub fn transform_vector(&self, v: &VectorN<N, D>) -> VectorN<N, D> {
+        self * v
+    }
+}
+
+impl<N: Real, D: DimNameAdd<U1>, C: TCategory> Transform<N, D, C>
+where C: SubTCategoryOf<TProjective>,
+      DefaultAllocator: Allocator<N, DimNameSum<D, U1>, DimNameSum<D, U1>>
+        + Allocator<N, DimNameSum<D, U1>>
+        + Allocator<N, D, D>
+        + Allocator<N, D>,
+{
+    /// Transform the given point by the inverse of this transformation.
+    /// This may be cheaper than inverting the transformation and transforming
+    /// the point.
+    #[inline]
+    pub fn inverse_transform_point(&self, pt: &Point<N, D>) -> Point<N, D> {
+        self.two_sided_inverse() * pt
+    }
+
+    /// Transform the given vector by the inverse of this transformation.
+    /// This may be cheaper than inverting the transformation and transforming
+    /// the vector.
+    #[inline]
+    pub fn inverse_transform_vector(&self, v: &VectorN<N, D>) -> VectorN<N, D> {
+        self.two_sided_inverse() * v
+    }
+}
+
 impl<N: Real, D: DimNameAdd<U1>> Transform<N, D, TGeneral>
 where DefaultAllocator: Allocator<N, DimNameSum<D, U1>, DimNameSum<D, U1>>
 {

src/geometry/transform_alga.rs

@@ -96,12 +96,12 @@ where
 {
     #[inline]
     fn transform_point(&self, pt: &Point<N, D>) -> Point<N, D> {
-        self * pt
+        self.transform_point(pt)
     }
 
     #[inline]
     fn transform_vector(&self, v: &VectorN<N, D>) -> VectorN<N, D> {
-        self * v
+        self.transform_vector(v)
     }
 }
 
@@ -116,12 +116,12 @@ where
 {
     #[inline]
     fn inverse_transform_point(&self, pt: &Point<N, D>) -> Point<N, D> {
-        self.two_sided_inverse() * pt
+        self.inverse_transform_point(pt)
     }
 
     #[inline]
     fn inverse_transform_vector(&self, v: &VectorN<N, D>) -> VectorN<N, D> {
-        self.two_sided_inverse() * v
+        self.inverse_transform_vector(v)
     }
 }
 

src/geometry/translation.rs

@@ -11,13 +11,15 @@ use serde::{Deserialize, Deserializer, Serialize, Serializer};
 #[cfg(feature = "abomonation-serialize")]
 use abomonation::Abomonation;
 
-use alga::general::{ClosedNeg, Real};
+use alga::general::{ClosedAdd, ClosedNeg, ClosedSub, Real};
 
 use base::allocator::Allocator;
 use base::dimension::{DimName, DimNameAdd, DimNameSum, U1};
 use base::storage::Owned;
 use base::{DefaultAllocator, MatrixN, Scalar, VectorN};
 
+use geometry::Point;
+
 /// A translation.
 #[repr(C)]
 #[derive(Debug)]
@@ -190,6 +192,40 @@ where DefaultAllocator: Allocator<N, D>
     }
 }
 
+impl<N: Scalar + ClosedAdd, D: DimName> Translation<N, D>
+where DefaultAllocator: Allocator<N, D>
+{
+    /// Translate the given point.
+    ///
+    /// # Example
+    /// ```
+    /// # use nalgebra::{Translation3, Point3};
+    /// let t = Translation3::new(1.0, 2.0, 3.0);
+    /// let transformed_point = t.transform_point(&Point3::new(4.0, 5.0, 6.0));
+    /// assert_eq!(transformed_point, Point3::new(5.0, 7.0, 9.0));
+    #[inline]
+    pub fn transform_point(&self, pt: &Point<N, D>) -> Point<N, D> {
+        pt + &self.vector
+    }
+}
+
+impl<N: Scalar + ClosedSub, D: DimName> Translation<N, D>
+where DefaultAllocator: Allocator<N, D>
+{
+    /// Translate the given point by the inverse of this translation.
+    ///
+    /// # Example
+    /// ```
+    /// # use nalgebra::{Translation3, Point3};
+    /// let t = Translation3::new(1.0, 2.0, 3.0);
+    /// let transformed_point = t.inverse_transform_point(&Point3::new(4.0, 5.0, 6.0));
+    /// assert_eq!(transformed_point, Point3::new(3.0, 3.0, 3.0));
+    #[inline]
+    pub fn inverse_transform_point(&self, pt: &Point<N, D>) -> Point<N, D> {
+        pt - &self.vector
+    }
+}
+
 impl<N: Scalar + Eq, D: DimName> Eq for Translation<N, D> where DefaultAllocator: Allocator<N, D> {}
 
 impl<N: Scalar + PartialEq, D: DimName> PartialEq for Translation<N, D>

src/geometry/translation_alga.rs

@@ -76,7 +76,7 @@ where DefaultAllocator: Allocator<N, D>
 {
     #[inline]
     fn transform_point(&self, pt: &Point<N, D>) -> Point<N, D> {
-        pt + &self.vector
+        self.transform_point(pt)
     }
 
     #[inline]
@@ -90,7 +90,7 @@ where DefaultAllocator: Allocator<N, D>
 {
     #[inline]
     fn inverse_transform_point(&self, pt: &Point<N, D>) -> Point<N, D> {
-        pt - &self.vector
+        self.inverse_transform_point(pt)
     }
 
     #[inline]

src/geometry/unit_complex.rs

@@ -3,8 +3,8 @@ use num_complex::Complex;
 use std::fmt;
 
 use alga::general::Real;
-use base::{Matrix2, Matrix3, Unit, Vector1};
+use base::{Matrix2, Matrix3, Unit, Vector1, Vector2};
-use geometry::Rotation2;
+use geometry::{Rotation2, Point2};
 
 /// A complex number with a norm equal to 1.
 pub type UnitComplex<N> = Unit<Complex<N>>;
@@ -251,6 +251,72 @@ impl<N: Real> UnitComplex<N> {
     pub fn to_homogeneous(&self) -> Matrix3<N> {
         self.to_rotation_matrix().to_homogeneous()
     }
+
+    /// Rotate the given point by this unit complex number.
+    ///
+    /// # Example
+    /// ```
+    /// # #[macro_use] extern crate approx;
+    /// # use nalgebra::{UnitComplex, Point2};
+    /// # use std::f32;
+    /// let rot = UnitComplex::new(f32::consts::FRAC_PI_2);
+    /// let transformed_point = rot.transform_point(&Point2::new(1.0, 2.0));
+    /// assert_relative_eq!(transformed_point, Point2::new(-2.0, 1.0), epsilon = 1.0e-6);
+    /// ```
+    #[inline]
+    pub fn transform_point(&self, pt: &Point2<N>) -> Point2<N> {
+        self * pt
+    }
+
+    /// Rotate the given vector by this unit complex number.
+    ///
+    /// # Example
+    /// ```
+    /// # #[macro_use] extern crate approx;
+    /// # use nalgebra::{UnitComplex, Vector2};
+    /// # use std::f32;
+    /// let rot = UnitComplex::new(f32::consts::FRAC_PI_2);
+    /// let transformed_vector = rot.transform_vector(&Vector2::new(1.0, 2.0));
+    /// assert_relative_eq!(transformed_vector, Vector2::new(-2.0, 1.0), epsilon = 1.0e-6);
+    /// ```
+    #[inline]
+    pub fn transform_vector(&self, v: &Vector2<N>) -> Vector2<N> {
+        self * v
+    }
+
+    /// Rotate the given point by the inverse of this unit complex number.
+    ///
+    /// # Example
+    /// ```
+    /// # #[macro_use] extern crate approx;
+    /// # use nalgebra::{UnitComplex, Point2};
+    /// # use std::f32;
+    /// let rot = UnitComplex::new(f32::consts::FRAC_PI_2);
+    /// let transformed_point = rot.inverse_transform_point(&Point2::new(1.0, 2.0));
+    /// assert_relative_eq!(transformed_point, Point2::new(2.0, -1.0), epsilon = 1.0e-6);
+    /// ```
+    #[inline]
+    pub fn inverse_transform_point(&self, pt: &Point2<N>) -> Point2<N> {
+        // FIXME: would it be useful performancewise not to call inverse explicitly (i-e. implement
+        // the inverse transformation explicitly here) ?
+        self.inverse() * pt
+    }
+
+    /// Rotate the given vector by the inverse of this unit complex number.
+    ///
+    /// # Example
+    /// ```
+    /// # #[macro_use] extern crate approx;
+    /// # use nalgebra::{UnitComplex, Vector2};
+    /// # use std::f32;
+    /// let rot = UnitComplex::new(f32::consts::FRAC_PI_2);
+    /// let transformed_vector = rot.inverse_transform_vector(&Vector2::new(1.0, 2.0));
+    /// assert_relative_eq!(transformed_vector, Vector2::new(2.0, -1.0), epsilon = 1.0e-6);
+    /// ```
+    #[inline]
+    pub fn inverse_transform_vector(&self, v: &Vector2<N>) -> Vector2<N> {
+        self.inverse() * v
+    }
 }
 
 impl<N: Real + fmt::Display> fmt::Display for UnitComplex<N> {

src/geometry/unit_complex_alga.rs

@@ -63,12 +63,12 @@ where DefaultAllocator: Allocator<N, U2>
 {
     #[inline]
     fn transform_point(&self, pt: &Point2<N>) -> Point2<N> {
-        self * pt
+        self.transform_point(pt)
     }
 
     #[inline]
     fn transform_vector(&self, v: &Vector2<N>) -> Vector2<N> {
-        self * v
+        self.transform_vector(v)
     }
 }
 
@@ -77,14 +77,12 @@ where DefaultAllocator: Allocator<N, U2>
 {
     #[inline]
     fn inverse_transform_point(&self, pt: &Point2<N>) -> Point2<N> {
-        // FIXME: would it be useful performancewise not to call inverse explicitly (i-e. implement
+        self.inverse_transform_point(pt)
-        // the inverse transformation explicitly here) ?
-        self.inverse() * pt
     }
 
     #[inline]
     fn inverse_transform_vector(&self, v: &Vector2<N>) -> Vector2<N> {
-        self.inverse() * v
+        self.inverse_transform_vector(v)
     }
 }