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122 lines (118 loc) · 4.3 KB
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/* FortuneAlgorithm
* Copyright (C) 2018 Pierre Vigier
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "Box.h"
bool Box::contains(const Vector2& point) const
{
return point.x >= left - EPSILON && point.x <= right + EPSILON &&
point.y >= bottom - EPSILON && point.y <= top + EPSILON;
}
Box::Intersection Box::getFirstIntersection(const Vector2& origin, const Vector2& direction) const
{
// origin must be in the box
Intersection intersection;
double t = std::numeric_limits<double>::infinity();
if (direction.x > 0.0)
{
t = (right - origin.x) / direction.x;
intersection.side = Side::RIGHT;
intersection.point = origin + t * direction;
}
else if (direction.x < 0.0)
{
t = (left - origin.x) / direction.x;
intersection.side = Side::LEFT;
intersection.point = origin + t * direction;
}
if (direction.y > 0.0)
{
double newT = (top - origin.y) / direction.y;
if (newT < t)
{
intersection.side = Side::TOP;
intersection.point = origin + newT * direction;
}
}
else if (direction.y < 0.0)
{
double newT = (bottom - origin.y) / direction.y;
if (newT < t)
{
intersection.side = Side::BOTTOM;
intersection.point = origin + newT * direction;
}
}
return intersection;
}
int Box::getIntersections(const Vector2& origin, const Vector2& destination, std::array<Intersection, 2>& intersections) const
{
// WARNING: If the intersection is a corner, both intersections are equals
Vector2 direction = destination - origin;
std::array<double, 2> t;
std::size_t i = 0; // index of the current intersection
// Left
if (origin.x < left - EPSILON || destination.x < left - EPSILON)
{
t[i] = (left - origin.x) / direction.x;
if (t[i] > EPSILON && t[i] < 1.0 - EPSILON)
{
intersections[i].side = Side::LEFT;
intersections[i].point = origin + t[i] * direction;
if (intersections[i].point.y >= bottom - EPSILON && intersections[i].point.y <= top + EPSILON)
++i;
}
}
// Right
if (origin.x > right + EPSILON || destination.x > right + EPSILON)
{
t[i] = (right - origin.x) / direction.x;
if (t[i] > EPSILON && t[i] < 1.0 - EPSILON)
{
intersections[i].side = Side::RIGHT;
intersections[i].point = origin + t[i] * direction;
if (intersections[i].point.y >= bottom - EPSILON && intersections[i].point.y <= top + EPSILON)
++i;
}
}
// Bottom
if (origin.y < bottom - EPSILON || destination.y < bottom - EPSILON)
{
t[i] = (bottom - origin.y) / direction.y;
if (i < 2 && t[i] > EPSILON && t[i] < 1.0 - EPSILON)
{
intersections[i].side = Side::BOTTOM;
intersections[i].point = origin + t[i] * direction;
if (intersections[i].point.x >= left - EPSILON && intersections[i].point.x <= right + EPSILON)
++i;
}
}
// Top
if (origin.y > top + EPSILON || destination.y > top + EPSILON)
{
t[i] = (top - origin.y) / direction.y;
if (i < 2 && t[i] > EPSILON && t[i] < 1.0 - EPSILON)
{
intersections[i].side = Side::TOP;
intersections[i].point = origin + t[i] * direction;
if (intersections[i].point.x >= left - EPSILON && intersections[i].point.x <= right + EPSILON)
++i;
}
}
// Sort the intersections from the nearest to the farthest
if (i == 2 && t[0] > t[1])
std::swap(intersections[0], intersections[1]);
return i;
}