1 #define __PERSPECTIVE_LINE_C__
3 /*
4 * Perspective line for 3D perspectives
5 *
6 * Authors:
7 * Maximilian Albert <Anhalter42@gmx.de>
8 *
9 * Copyright (C) 2007 authors
10 *
11 * Released under GNU GPL, read the file 'COPYING' for more information
12 */
14 #include "perspective-line.h"
15 #include "desktop.h"
17 namespace Box3D {
19 PerspectiveLine::PerspectiveLine (NR::Point const &pt, Box3D::Axis const axis, Perspective3D *perspective) :
20 Line (pt, *(perspective->get_vanishing_point(axis)), true)
21 {
22 g_assert (perspective != NULL);
23 g_assert (Box3D::is_single_axis_direction (axis));
25 if (perspective->get_vanishing_point(axis)->state == VP_INFINITE) {
26 this->set_direction(perspective->get_vanishing_point(axis)->v_dir);
27 }
28 this->vp_dir = axis;
29 this->persp = perspective;
30 }
32 // This function makes sure not to return NR::Nothing()
33 // FIXME: How to gracefully handle parallel lines?
34 NR::Maybe<NR::Point> PerspectiveLine::intersect (Line const &line)
35 {
36 NR::Maybe<NR::Point> pt = this->Line::intersect(line);
37 if (!pt) {
38 Box3D::VanishingPoint vp = *(persp->get_vanishing_point(vp_dir));
39 if (vp.state == VP_INFINITE) {
40 pt = vp;
41 } else {
42 pt = NR::Point (0.0, 0.0); // FIXME: Better solution needed
43 }
44 }
45 return pt;
46 }
48 // FIXME: Do we really need two intersection methods?
49 NR::Point PerspectiveLine::meet(Line const &line)
50 {
51 return *intersect(line); // works since intersect() does not return NR::Nothing()
52 }
54 NR::Maybe<NR::Point> PerspectiveLine::intersection_with_viewbox (SPDesktop *desktop)
55 {
56 NR::Rect vb = desktop->get_display_area();
57 /* remaining viewbox corners */
58 NR::Point ul (vb.min()[NR::X], vb.max()[NR::Y]);
59 NR::Point lr (vb.max()[NR::X], vb.min()[NR::Y]);
61 std::pair <NR::Point, NR::Point> e = side_of_intersection (vb.min(), lr, vb.max(), ul, this->pt, this->v_dir);
62 if (e.first == e.second) {
63 // perspective line lies outside the canvas
64 return NR::Nothing();
65 }
67 Line line (e.first, e.second);
68 return this->intersect (line);
69 }
71 } // namespace Box3D
73 /*
74 Local Variables:
75 mode:c++
76 c-file-style:"stroustrup"
77 c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
78 indent-tabs-mode:nil
79 fill-column:99
80 End:
81 */
82 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :