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Lib/Include/CML/mathlib/quaternion_basis.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
+ */
+
+#ifndef quaternion_basis_h
+#define quaternion_basis_h
+
+#include <cml/mathlib/checking.h>
+
+/* Functions for getting the basis vectors of a quaternion rotation. */
+
+namespace cml {
+
+/** Get the i'th basis vector of a quaternion rotation */
+template < class QuatT > vector< typename QuatT::value_type, fixed<3> >
+quaternion_get_basis_vector(const QuatT& q, size_t i)
+{
+    typedef QuatT quaternion_type;
+    typedef typename quaternion_type::value_type value_type;
+    typedef typename quaternion_type::order_type order_type;
+    typedef vector< value_type, fixed<3> > vector_type;
+
+    /* Checking */
+    detail::CheckQuat(q);
+    detail::CheckIndex3(i);
+
+    size_t j, k;
+    cyclic_permutation(i, i, j, k);
+    
+    /* @todo: Clean this up. */
+    const size_t W = order_type::W;
+    const size_t I = order_type::X + i;
+    const size_t J = order_type::X + j;
+    const size_t K = order_type::X + k;
+    
+    value_type j2 = q[J] + q[J];
+    value_type k2 = q[K] + q[K];
+    
+    /* @todo: use set_permuted() for the following when available. */
+
+    vector_type result;
+    result[i] = value_type(1) - q[J] * j2 - q[K] * k2;
+    result[j] = q[I] * j2 + q[W] * k2;
+    result[k] = q[I] * k2 - q[W] * j2;
+    return result;
+}
+
+/** Get the x basis vector of a quaternion rotation */
+template < class QuatT > vector< typename QuatT::value_type, fixed<3> >
+quaternion_get_x_basis_vector(const QuatT& q) {
+    return quaternion_get_basis_vector(q,0);
+}
+
+/** Get the y basis vector of a quaternion rotation */
+template < class QuatT > vector< typename QuatT::value_type, fixed<3> >
+quaternion_get_y_basis_vector(const QuatT& q) {
+    return quaternion_get_basis_vector(q,1);
+}
+
+/** Get the z basis vector of a quaternion rotation */
+template < class QuatT > vector< typename QuatT::value_type, fixed<3> >
+quaternion_get_z_basis_vector(const QuatT& q) {
+    return quaternion_get_basis_vector(q,2);
+}
+
+/** Get the basis vectors of a quaternion rotation */
+template < class QuatT, typename E, class A > void
+quaternion_get_basis_vectors(
+    const QuatT& q,
+    vector<E,A>& x,
+    vector<E,A>& y,
+    vector<E,A>& z)
+{
+    x = quaternion_get_x_basis_vector(q);
+    y = quaternion_get_y_basis_vector(q);
+    z = quaternion_get_z_basis_vector(q);
+}
+
+} // namespace cml
+
+#endif