1 /*
2 * Generic auxiliary routines for 3D axes
3 *
4 * Authors:
5 * Maximilian Albert <Anhalter42@gmx.de>
6 *
7 * Copyright (C) 2007 authors
8 *
9 * Released under GNU GPL, read the file 'COPYING' for more information
10 */
12 #ifndef SEEN_AXIS_MANIP_H
13 #define SEEN_AXIS_MANIP_H
15 #include <gtk/gtk.h>
16 #include "libnr/nr-point.h"
18 namespace Box3D {
20 const double epsilon = 1e-6;
22 // The X-/Y-/Z-axis corresponds to the first/second/third digit
23 // in binary representation, respectively.
24 enum Axis {
25 X = 1,
26 Y = 2,
27 Z = 4,
28 XY = 3,
29 XZ = 5,
30 YZ = 6,
31 XYZ = 7,
32 NONE = 0
33 };
35 // We use the fourth bit in binary representation
36 // to indicate whether a face is front or rear.
37 enum FrontOrRear { // find a better name
38 FRONT = 0,
39 REAR = 8
40 };
42 extern Axis axes[3];
43 extern Axis planes[3];
44 extern FrontOrRear face_positions [2];
46 // Given a bit sequence that unambiguously specifies the face of a 3D box,
47 // return a number between 0 and 5 corresponding to that particular face
48 // (which is normally used to index an array). Return -1 if the bit sequence
49 // does not specify a face. A face can either be given by its plane (e.g, XY)
50 // or by the axis that is orthogonal to it (e.g., Z).
51 inline gint face_to_int (guint face_id) {
52 switch (face_id) {
53 case 1: return 0;
54 case 2: return 2;
55 case 4: return 4;
56 case 3: return 4;
57 case 5: return 2;
58 case 6: return 0;
60 case 9: return 1;
61 case 10: return 3;
62 case 12: return 5;
63 case 11: return 5;
64 case 13: return 3;
65 case 14: return 1;
67 default: return -1;
68 }
69 }
71 inline guint opposite_face (guint face_id) {
72 return face_id + ((face_id % 2 == 0) ? 1 : -1);
73 }
75 inline guint number_of_axis_directions (Box3D::Axis axis) {
76 guint num = 0;
77 if (axis & Box3D::X) num++;
78 if (axis & Box3D::Y) num++;
79 if (axis & Box3D::Z) num++;
81 return num;
82 }
84 inline bool is_plane (Box3D::Axis plane) {
85 return (number_of_axis_directions (plane) == 2);
86 }
88 inline bool is_single_axis_direction (Box3D::Axis dir) {
89 // tests whether dir is nonzero and a power of 2
90 return (!(dir & (dir - 1)) && dir);
91 }
93 // Warning: We don't check that axis really unambiguously specifies a plane.
94 // Make sure this is the case when calling this function.
95 inline guint face_containing_corner (Box3D::Axis axis, guint corner) {
96 if (!is_single_axis_direction (axis)) {
97 axis = (Box3D::Axis) (axis ^ Box3D::XYZ);
98 }
99 return face_to_int (axis ^ ((corner & axis) ? Box3D::REAR : Box3D::FRONT));
100 }
103 /**
104 * Given two axis directions out of {X, Y, Z} or the corresponding plane, return the remaining one
105 * We don't check if 'plane' really specifies a plane (i.e., if it consists of precisely two directions).
106 */
107 inline Box3D::Axis third_axis_direction (Box3D::Axis dir1, Box3D::Axis dir2) {
108 return (Box3D::Axis) ((dir1 + dir2) ^ 0x7);
109 }
110 inline Box3D::Axis third_axis_direction (Box3D::Axis plane) {
111 return (Box3D::Axis) (plane ^ 0x7);
112 }
114 /* returns the first/second axis direction occuring in the (possibly compound) expression 'dirs' */
115 inline Box3D::Axis extract_first_axis_direction (Box3D::Axis dirs) {
116 if (dirs & Box3D::X) return Box3D::X;
117 if (dirs & Box3D::Y) return Box3D::Y;
118 if (dirs & Box3D::Z) return Box3D::Z;
119 return Box3D::NONE;
120 }
121 inline Box3D::Axis extract_second_axis_direction (Box3D::Axis dirs) {
122 return extract_first_axis_direction ((Box3D::Axis) (dirs ^ extract_first_axis_direction(dirs)));
123 }
125 inline Box3D::Axis orth_plane_or_axis (Box3D::Axis axis) {
126 return (Box3D::Axis) (Box3D::XYZ ^ axis);
127 }
129 /* returns an axis direction perpendicular to the ones occuring in the (possibly compound) expression 'dirs' */
130 inline Box3D::Axis get_perpendicular_axis_direction (Box3D::Axis dirs) {
131 if (!(dirs & Box3D::X)) return Box3D::X;
132 if (!(dirs & Box3D::Y)) return Box3D::Y;
133 if (!(dirs & Box3D::Z)) return Box3D::Z;
134 return Box3D::NONE;
135 }
137 inline gchar * string_from_axes (Box3D::Axis axes) {
138 GString *pstring = g_string_new("");
139 if (axes & Box3D::X) g_string_append_printf (pstring, "X");
140 if (axes & Box3D::Y) g_string_append_printf (pstring, "Y");
141 if (axes & Box3D::Z) g_string_append_printf (pstring, "Z");
142 return pstring->str;
143 }
145 std::pair <Axis, Axis> get_remaining_axes (Axis axis);
147 } // namespace Box3D
149 #endif /* !SEEN_AXIS_MANIP_H */
151 /*
152 Local Variables:
153 mode:c++
154 c-file-style:"stroustrup"
155 c-file-offsets:((innamespace . 0)(inline-open . 0))
156 indent-tabs-mode:nil
157 fill-column:99
158 End:
159 */
160 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :