ladybird/Libraries/LibDraw/Triangle.h
Shannon Booth 6ea70f5724 LibDraw: Add beginnings of a triangle class
Currently the points of a triangle do not need to be initialised in a
certain orientation. Currently, the only real method in the class is
`contains`. However we can continue extending the class if and when we
need more functionality.
2020-01-19 08:45:23 +01:00

78 lines
2.6 KiB
C++

/*
* Copyright (c) 2020, Shannon Booth <shannon.ml.booth@gmail.com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <LibDraw/Point.h>
class Triangle {
public:
Triangle(Point a, Point b, Point c)
: m_a(a)
, m_b(b)
, m_c(c)
{
m_det = (m_b.x() - m_a.x()) * (m_c.y() - m_a.y()) - (m_b.y() - m_a.y()) * (m_c.x() - m_a.x());
}
Point a() const { return m_a; }
Point b() const { return m_b; }
Point c() const { return m_c; }
bool contains(Point p) const
{
int x = p.x();
int y = p.y();
int ax = m_a.x();
int bx = m_b.x();
int cx = m_c.x();
int ay = m_a.y();
int by = m_b.y();
int cy = m_c.y();
if (m_det * ((bx - ax) * (y - ay) - (by - ay) * (x - ax)) <= 0)
return false;
if (m_det * ((cx - bx) * (y - by) - (cy - by) * (x - bx)) <= 0)
return false;
if (m_det * ((ax - cx) * (y - cy) - (ay - cy) * (x - cx)) <= 0)
return false;
return true;
}
String to_string() const { return String::format("(%s,%s,%s)", m_a.to_string().characters(), m_b.to_string().characters(), m_c.to_string().characters()); }
private:
int m_det;
Point m_a;
Point m_b;
Point m_c;
};
inline const LogStream& operator<<(const LogStream& stream, const Triangle& value)
{
return stream << value.to_string();
}