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Lib/Include/CML/quaternion/conjugate.h

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+/* -*- C++ -*- ------------------------------------------------------------
+ 
+Copyright (c) 2007 Jesse Anders and Demian Nave http://cmldev.net/
+
+The Configurable Math Library (CML) is distributed under the terms of the
+Boost Software License, v1.0 (see cml/LICENSE for details).
+
+ *-----------------------------------------------------------------------*/
+/** @file
+ *  @brief Defines an operator for quaternion conjugation.
+ */
+
+#ifndef conjugate_h
+#define conjugate_h
+
+#include <cml/quaternion/quaternion_expr.h>
+
+namespace cml {
+namespace et {
+
+/** An expression node for conjugating a quaternion. */
+template<class ExprT>
+class ConjugateOp
+{
+  public:
+
+    typedef ConjugateOp<ExprT> expr_type;
+
+    /* Record ary-ness of the expression: */
+    typedef unary_expression expr_ary;
+
+    /* Copy the expression by value into higher-up expressions: */
+    typedef expr_type expr_const_reference;
+
+    typedef typename ExprT::value_type value_type;
+    typedef quaternion_result_tag result_tag;
+    typedef typename ExprT::size_tag size_tag;
+
+    /* Store the expression traits for the subexpression: */
+    typedef ExprTraits<ExprT> expr_traits;
+
+    /* Reference type for the subexpression: */
+    typedef typename expr_traits::const_reference expr_reference;
+
+    /* Get the result type (same as for subexpression): */
+    typedef typename expr_traits::result_type result_type;
+
+    /* For matching by assignability: */
+    typedef cml::et::not_assignable_tag assignable_tag;
+
+    /* Get the temporary type: */
+    typedef typename result_type::temporary_type temporary_type;
+
+    /* Get the vector type: */
+    typedef typename result_type::vector_type vector_type;
+
+    /* Get the imaginary part type: */
+    typedef typename vector_type::subvector_type imaginary_type;
+
+    /* Record the order type: */
+    typedef typename result_type::order_type order_type;
+
+
+  public:
+
+    /** Record result size as an enum. */
+    enum { array_size = ExprT::array_size };
+
+    /** Localize the ordering as an enum. */
+    enum {
+        W = order_type::W,
+        X = order_type::X,
+        Y = order_type::Y,
+        Z = order_type::Z
+    };
+
+
+  public:
+
+    /** Return the real part of the expression. */
+    value_type real() const {
+        return m_expr.real();
+    }
+
+    /** Return the vector part of the expression. */
+    imaginary_type imaginary() const {
+        return -m_expr.imaginary();
+    }
+
+    /** Return the Cayley norm of the expression. */
+    value_type norm() const {
+        return length_squared();
+    }
+
+    /** Return square of the quaternion length. */
+    value_type length_squared() const {
+        return dot(
+                QuaternionXpr<expr_type>(*this),
+                QuaternionXpr<expr_type>(*this));
+    }
+
+    /** Return the quaternion length. */
+    value_type length() const {
+        return std::sqrt(length_squared());
+    }
+
+    /** Return the result as a normalized quaternion. */
+    temporary_type normalize() const {
+        temporary_type q(QuaternionXpr<expr_type>(*this));
+        return q.normalize();
+    }
+
+    /** Compute conjugated result at index i.
+     *
+     * The conjugate of quaternion s + v is s - v.
+     */
+    value_type operator[](size_t i) const {
+        return (i == W) ? m_expr[W] : - m_expr[i] ;
+    }
+
+
+  public:
+
+    /** Return size of this expression (same as argument's size). */
+    size_t size() const {
+        return m_expr.size();
+    }
+
+    /** Return reference to contained expression. */
+    expr_reference expression() const { return m_expr; }
+
+
+  public:
+
+    /** Construct from the subexpression. */
+    explicit ConjugateOp(expr_reference expr) : m_expr(expr) {}
+
+    /** Copy constructor. */
+    ConjugateOp(const expr_type& e) : m_expr(e.m_expr) {}
+
+
+  protected:
+
+    expr_reference m_expr;
+
+
+  private:
+
+    /* Cannot be assigned to: */
+    expr_type& operator=(const expr_type&);
+};
+
+/** Expression traits class for ConjugateOp<>. */
+template<class ExprT>
+struct ExprTraits< ConjugateOp<ExprT> >
+{
+    typedef ConjugateOp<ExprT> expr_type;
+    typedef ExprT arg_type;
+
+    typedef typename expr_type::value_type value_type;
+    typedef typename expr_type::expr_const_reference const_reference;
+    typedef typename expr_type::result_tag result_tag;
+    typedef typename expr_type::size_tag size_tag;
+    typedef typename expr_type::result_type result_type;
+    typedef typename expr_type::assignable_tag assignable_tag;
+    typedef expr_node_tag node_tag;
+
+    value_type get(const expr_type& v, size_t i) const { return v[i]; }
+    size_t size(const expr_type& e) const { return e.size(); }
+};
+
+} // namespace et
+
+/** Conjugation of a quaternion. */
+template<typename E, class AT, class OT, class CT> inline
+et::QuaternionXpr< et::ConjugateOp< quaternion<E,AT,OT,CT> > >
+conjugate(const quaternion<E,AT,OT,CT>& arg)
+{
+    typedef et::ConjugateOp< quaternion<E,AT,OT,CT> > ExprT;
+    return et::QuaternionXpr<ExprT>(ExprT(arg));
+}
+
+/** Conjugation of a QuaternionXpr. */
+template<class XprT> inline
+et::QuaternionXpr< et::ConjugateOp<XprT> >
+conjugate(QUATXPR_ARG_TYPE arg)
+{
+    typedef et::ConjugateOp<XprT> ExprT;
+    return et::QuaternionXpr<ExprT>(ExprT(arg.expression()));
+}
+
+} // namespace cml
+
+#endif
+
+// -------------------------------------------------------------------------
+// vim:ft=cpp