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#define __PERSPECTIVE_LINE_C__
/*
* Perspective line for 3D perspectives
*
* Authors:
* Maximilian Albert <Anhalter42@gmx.de>
*
* Copyright (C) 2007 authors
*
* Released under GNU GPL, read the file 'COPYING' for more information
*/
#include "perspective-line.h"
#include "desktop.h"
namespace Box3D {
PerspectiveLine::PerspectiveLine (NR::Point const &pt, Box3D::Axis const axis, Perspective3D *perspective) :
Line (pt, *(perspective->get_vanishing_point(axis)), true)
{
g_assert (perspective != NULL);
g_assert (Box3D::is_single_axis_direction (axis));
if (perspective->get_vanishing_point(axis)->state == VP_INFINITE) {
this->set_direction(perspective->get_vanishing_point(axis)->v_dir);
}
this->vp_dir = axis;
this->persp = perspective;
}
// This function makes sure not to return NR::Nothing()
// FIXME: How to gracefully handle parallel lines?
NR::Maybe<NR::Point> PerspectiveLine::intersect (Line const &line)
{
NR::Maybe<NR::Point> pt = this->Line::intersect(line);
if (!pt) {
Box3D::VanishingPoint vp = *(persp->get_vanishing_point(vp_dir));
if (vp.state == VP_INFINITE) {
pt = vp;
} else {
pt = NR::Point (0.0, 0.0); // FIXME: Better solution needed
}
}
return pt;
}
// FIXME: Do we really need two intersection methods?
NR::Point PerspectiveLine::meet(Line const &line)
{
return *intersect(line); // works since intersect() does not return NR::Nothing()
}
NR::Point PerspectiveLine::pt_with_given_cross_ratio (NR::Point const &C, NR::Point const &D, double gamma)
{
if (persp->get_vanishing_point (vp_dir)->is_finite()) {
NR::Point V (*persp->get_vanishing_point (vp_dir));
return fourth_pt_with_given_cross_ratio (V, C, D, gamma);
} else {
if (fabs (gamma - 1) < epsilon) {
g_warning ("Cannot compute point with given cross ratio.\n");
return NR::Point (0.0, 0.0);
}
Line line (C, D);
double lambda_C = line.lambda (C);
double lambda_D = line.lambda (D);
return line.point_from_lambda ((lambda_D - gamma * lambda_C) / (1 - gamma));
}
}
NR::Maybe<NR::Point> PerspectiveLine::intersection_with_viewbox (SPDesktop *desktop)
{
NR::Rect vb = desktop->get_display_area();
/* remaining viewbox corners */
NR::Point ul (vb.min()[NR::X], vb.max()[NR::Y]);
NR::Point lr (vb.max()[NR::X], vb.min()[NR::Y]);
std::pair <NR::Point, NR::Point> e = side_of_intersection (vb.min(), lr, vb.max(), ul, this->pt, this->v_dir);
if (e.first == e.second) {
// perspective line lies outside the canvas
return NR::Nothing();
}
Line line (e.first, e.second);
return this->intersect (line);
}
} // namespace Box3D
/*
Local Variables:
mode:c++
c-file-style:"stroustrup"
c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
indent-tabs-mode:nil
fill-column:99
End:
*/
// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :
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