Dogcows Code - chaz/yoink/blob - src/moof/cml/mathlib/picking.h

   1 /* -*- C++ -*- ------------------------------------------------------------
   2
   3 Copyright (c) 2007 Jesse Anders and Demian Nave http://cmldev.net/
   4
   5 The Configurable Math Library (CML) is distributed under the terms of the
   6 Boost Software License, v1.0 (see cml/LICENSE for details).
   7
   8  *-----------------------------------------------------------------------*/
   9 /** @file
  10  *  @brief
  11  */
  12
  13 #ifndef picking_h
  14 #define picking_h
  15
  16 #include <cml/mathlib/projection.h>
  17
  18 /* Functions for picking with rays, volumes, and drag-enclosed volumes. */
  19
  20 namespace cml {
  21
  22 /* Support function for extracting the near and far depth range values from
  23  * a viewport matrix.
  24   */
  25
  26 namespace detail {
  27
  28 // NOTE: Changed 'near' and 'far' to 'n' and 'f' to work around windows.h
  29 // 'near' and 'far' macros.
  30
  31 template < class MatT, typename Real > void
  32 depth_range_from_viewport_matrix(const MatT& viewport, Real& n, Real& f)
  33 {
  34     detail::CheckMatHomogeneous3D(viewport);
  35
  36     n = viewport.basis_element(3,2);
  37     f = viewport.basis_element(2,2) + n;
  38 }
  39
  40 } // namespace detail
  41
  42 /* Make a pick ray given screen coordinates and view, projection, and viewport
  43  * matrices. The origin of the ray lies in the near plane of the frustum; the
  44  * direction vector extends to the far plane if 'normalize' is false, and is
  45  * made unit-length if 'normalize' is true (its default value).
  46  *
  47  * Note that the origin of the ray lies in the near plane rather than
  48  * coinciding with the position of the virtual camera, as the latter gives
  49  * incorrect results when the projection is orthographic.
  50  *
  51  * Note also that the screen y coordinate increases from bottom to top rather
  52  * than top to bottom. If mouse coordinates are returned in window space where
  53  * the y coordinate increases from top to bottom (as is often the case), the
  54  * y value should be recomputed as 'y = <window height> - y' before being
  55  * submitted to this function.
  56  */
  57
  58 template < class MatT_1, class MatT_2, class MatT_3, typename E, class A >
  59 void make_pick_ray(
  60     E pick_x,
  61     E pick_y,
  62     const MatT_1& view,
  63     const MatT_2& projection,
  64     const MatT_3& viewport,
  65     vector<E,A>& origin,
  66     vector<E,A>& direction,
  67     bool normalize = true)
  68 {
  69     typedef vector<E,A> vector_type;
  70     typedef typename vector_type::value_type value_type;
  71
  72     // NOTE: Changed 'near' and 'far' to 'n' and 'f' to work around
  73     // windows.h 'near' and 'far' macros.
  74     value_type n, f;
  75     detail::depth_range_from_viewport_matrix(viewport, n, f);
  76
  77     origin =
  78         unproject_point(
  79             view,projection,viewport,vector_type(pick_x,pick_y,n)
  80         );
  81     direction =
  82         unproject_point(
  83             view,projection,viewport,vector_type(pick_x,pick_y,f)
  84         ) - origin;
  85     if (normalize) {
  86         direction.normalize();
  87     }
  88 }
  89
  90 /* Make a pick volume given the screen coordinates of the center of the
  91  * picking rect, the width and height of the picking rect, and view and
  92  * projection matrices.
  93  *
  94  * The volume is loaded into the 'planes' array. The planes are of the form
  95  * ax+by+cz+d = 0, and are in the order left, right, bottom, top, near, far.
  96  *
  97  * The z_clip argument should be either z_clip_neg_one or z_clip_zero, and
  98  * should correspond to the near z-clipping range of the projection matrix
  99  * argument.
 100  *
 101  * The 'normalize' argument indicates whether the output planes should be
 102  * normalized; its default value is 'true'.
 103  *
 104  * Note that the screen y coordinate increases from bottom to top rather
 105  * than top to bottom. If mouse coordinates are returned in window space where
 106  * the y coordinate increases from top to bottom (as is often the case), the
 107  * y value should be recomputed as 'y = <window height> - y' before being
 108  * submitted to this function.
 109  */
 110
 111 template < class MatT_1, class MatT_2, typename Real >
 112 void make_pick_volume(
 113     Real pick_x,
 114     Real pick_y,
 115     Real pick_width,
 116     Real pick_height,
 117     Real viewport_x,
 118     Real viewport_y,
 119     Real viewport_width,
 120     Real viewport_height,
 121     const MatT_1& view,
 122     const MatT_2& projection,
 123     Real planes[6][4],
 124     ZClip z_clip,
 125     bool normalize = true)
 126 {
 127     // FIXME: Should be promoted type...
 128     typedef matrix<
 129         Real, fixed<4,4>,
 130         typename MatT_1::basis_orient, typename MatT_1::layout >
 131     matrix_type;
 132
 133     matrix_type pick;
 134     matrix_pick(
 135         pick, pick_x, pick_y, pick_width, pick_height,
 136         viewport_x, viewport_y, viewport_width, viewport_height
 137     );
 138     cml::extract_frustum_planes(
 139         view,detail::matrix_concat_transforms_4x4(projection,pick),
 140         planes,z_clip,normalize);
 141 }
 142
 143 /* Make a pick volume given two opposite corners of a rectangle in screen
 144  * space, and view and projection matrices. The corners of the screen rect
 145  * need not be in any particular 'order' with regard to the values of the
 146  * coordinates.
 147  *
 148  * The volume is loaded into the 'planes' array. The planes are of the form
 149  * ax+by+cz+d = 0, and are in the order left, right, bottom, top, near, far.
 150  *
 151  * The z_clip argument should be either z_clip_neg_one or z_clip_zero, and
 152  * should correspond to the near z-clipping range of the projection matrix
 153  * argument.
 154  *
 155  * The 'normalize' argument indicates whether the output planes should be
 156  * normalized; its default value is 'true'.
 157  *
 158  * Note that the screen y coordinate increases from bottom to top rather
 159  * than top to bottom. If mouse coordinates are returned in window space where
 160  * the y coordinate increases from top to bottom (as is often the case), the
 161  * y value should be recomputed as 'y = <window height> - y' before being
 162  * submitted to this function.
 163  */
 164
 165 template < class MatT_1, class MatT_2, typename Real >
 166 void make_pick_drag_volume(
 167     Real pick_x1,
 168     Real pick_y1,
 169     Real pick_x2,
 170     Real pick_y2,
 171     Real viewport_x,
 172     Real viewport_y,
 173     Real viewport_width,
 174     Real viewport_height,
 175     const MatT_1& view,
 176     const MatT_2& projection,
 177     Real planes[6][4],
 178     ZClip z_clip,
 179     bool normalize = true)
 180 {
 181     typedef Real value_type;
 182
 183     make_pick_volume(
 184         (pick_x1+pick_x2)*value_type(.5),
 185         (pick_y1+pick_y2)*value_type(.5),
 186         std::fabs(pick_x2-pick_x1),
 187         std::fabs(pick_y2-pick_y1),
 188         viewport_x, viewport_y, viewport_width, viewport_height,
 189         view, projection, planes, z_clip, normalize
 190     );
 191 }
 192
 193 } // namespace cml
 194
 195 #endif