colobot/src/math/point.h

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// * This file is part of the COLOBOT source code
// * Copyright (C) 2012, Polish Portal of Colobot (PPC)
// *
// * This program is free software: you can redistribute it and/or modify
// * it under the terms of the GNU 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 General Public License for more details.
// *
// * You should have received a copy of the GNU General Public License
// * along with this program. If not, see http://www.gnu.org/licenses/.
/** @defgroup MathPointModule math/point.h
Contains the Point struct and related functions.
*/
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#pragma once
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#include "const.h"
#include "func.h"
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#include <cmath>
/* TODO
FPOINT RotatePoint(FPOINT center, float angle, FPOINT p);
FPOINT RotatePoint(float angle, FPOINT p);
FPOINT RotatePoint(float angle, float dist);
void RotatePoint(float cx, float cy, float angle, float &px, float &py);
float RotateAngle(FPOINT center, FPOINT p1, FPOINT p2);
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*/
// Math module namespace
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namespace Math
{
/* @{ */ // start of group
/** \struct Point math/point.h
\brief 2D point
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Represents a 2D point (x, y).
Contains the required methods for operating on points.
All methods are made inline to maximize optimization.
*/
struct Point
{
//! X coord
float x;
//! Y coord
float y;
//! Constructs a zero point: (0,0)
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inline Point()
{
LoadZero();
}
//! Constructs a point from given coords: (x,y)
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inline Point(float x, float y)
{
this->x = x;
this->y = y;
}
//! Sets the zero point: (0,0)
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inline void LoadZero()
{
x = y = 0.0f;
}
//! Returns the distance from (0,0) to the point (x,y)
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inline float Length()
{
return std::sqrt(x*x + y*y);
}
};
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//! Permutes two points
inline void Swap(Point &a, Point &b)
{
Point c;
c = a;
a = b;
b = c;
}
//! Returns the distance between two points
inline float Distance(const Point &a, const Point &b)
{
return sqrt((a.x-b.x)*(a.x-b.x) + (a.y-b.y)*(a.y-b.y));
}
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//! Returns py up on the line \a a - \a b
inline float MidPoint(const Point &a, const Point &b, float px)
{
if (IsEqual(a.x, b.x))
{
if (a.y < b.y)
return HUGE;
else
return -HUGE;
}
return (b.y-a.y) * (px-a.x) / (b.x-a.x) + a.y;
}
//! Calculates the parameters a and b of the linear function passing through \a p1 and \a p2
/** Returns \c false if the line is vertical.
\param p1,p2 points
\param a,b linear function parameters */
inline bool LinearFunction(const Point &p1, const Point &p2, float &a, float &b)
{
if ( IsZero(p1.x-p2.x) )
{
a = HUGE;
b = p2.x;
return false;
}
a = (p2.y-p1.y) / (p2.x-p1.x);
b = p2.y - p2.x*a;
return true;
}
//! Checks if the point is inside triangle defined by vertices \a a, \a b, \a c
inline bool IsInsideTriangle(Point a, Point b, Point c, const Point &p)
{
if ( p.x < a.x && p.x < b.x && p.x < c.x ) return false;
if ( p.x > a.x && p.x > b.x && p.x > c.x ) return false;
if ( p.y < a.y && p.y < b.y && p.y < c.y ) return false;
if ( p.y > a.y && p.y > b.y && p.y > c.y ) return false;
if ( a.x > b.x ) Swap(a,b);
if ( a.x > c.x ) Swap(a,c);
if ( c.x < a.x ) Swap(c,a);
if ( c.x < b.x ) Swap(c,b);
float n, m;
n = MidPoint(a, b, p.x);
m = MidPoint(a, c, p.x);
if ( (n>p.y || p.y>m) && (n<p.y || p.y<m) )
return false;
n = MidPoint(c, b, p.x);
m = MidPoint(c, a, p.x);
if ( (n>p.y || p.y>m) && (n<p.y || p.y<m) )
return false;
return true;
}
/* @} */ // end of group
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}; // namespace Math