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/*
* Authors:
* Thomas Holder
* Sergei Izmailov
*
* Copyright 2020 Authors
*
* SPDX-License-Identifier: LGPL-2.1 or MPL-1.1
*/
#include <2geom/basic-intersection.h>
#include <2geom/parallelogram.h>
#include <cassert>
namespace Geom {
namespace {
/// Return true if `p` is inside a unit rectangle
inline bool unit_rect_contains(Point const &p)
{
return 0 <= p.x() && p.x() <= 1 && //
0 <= p.y() && p.y() <= 1;
}
/// N'th corner of a unit rectangle
inline Point unit_rect_corner(unsigned i)
{
assert(i < 4);
unsigned const y = i >> 1;
unsigned const x = (i & 1) ^ y;
return Point(x, y);
}
} // namespace
Point Parallelogram::corner(unsigned i) const
{
assert(i < 4);
return unit_rect_corner(i) * m_affine;
}
Rect Parallelogram::bounds() const
{
Rect rect(corner(0), corner(2));
rect.expandTo(corner(1));
rect.expandTo(corner(3));
return rect;
}
bool Parallelogram::intersects(Parallelogram const &other) const
{
if (m_affine.isSingular() || other.m_affine.isSingular()) {
return false;
}
auto const affine1 = other.m_affine * m_affine.inverse();
auto const affine2 = affine1.inverse();
// case 1: any corner inside the other rectangle
for (unsigned i = 0; i != 4; ++i) {
auto const p = unit_rect_corner(i);
if (unit_rect_contains(p * affine1) || //
unit_rect_contains(p * affine2)) {
return true;
}
}
// case 2: any sides intersect (check diagonals)
for (unsigned i = 0; i != 2; ++i) {
auto const A = corner(i);
auto const B = corner((i + 2) % 4);
for (unsigned j = 0; j != 2; ++j) {
auto const C = other.corner(j);
auto const D = other.corner((j + 2) % 4);
if (non_collinear_segments_intersect(A, B, C, D)) {
return true;
}
}
}
return false;
}
bool Parallelogram::contains(Point const &p) const
{
return !m_affine.isSingular() && //
unit_rect_contains(p * m_affine.inverse());
}
bool Parallelogram::contains(Parallelogram const &other) const
{
if (m_affine.isSingular()) {
return false;
}
auto const inv = m_affine.inverse();
for (unsigned i = 0; i != 4; ++i) {
if (!unit_rect_contains(other.corner(i) * inv)) {
return false;
}
}
return true;
}
Coord Parallelogram::minExtent() const
{
return std::min(m_affine.expansionX(), //
m_affine.expansionY());
}
Coord Parallelogram::maxExtent() const
{
return std::max(m_affine.expansionX(), //
m_affine.expansionY());
}
bool Parallelogram::isSheared(Coord eps) const
{
return !are_near(dot(m_affine.xAxis(), m_affine.yAxis()), //
0.0, eps);
}
} // namespace Geom
/*
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:fileencoding=utf-8:textwidth=99 :
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