added suport for ballxpolygon collision ... VERY hacky

[physics.git] / src / mathw.cpp

/*
 *  Copyright (C) 2008 Patrik Gornicz, Gornicz_P (at) hotmail (dot) com.
 *
 *  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/>.
 */

#include "mathw.h"


/// ***** Public Methods *****

int mod(int x, int y)
{
  return x % y + (x < 0 ? y : 0);
}

// Vector2 Math

Vector2 vectorToLine
(
  const Vector2& vec,
  float x1,
  float y1,
  float x2,
  float y2
)
{
    float lineSize = (float) sqrt((x1 - x2) * (x1 - x2)
                                + (y1 - y2) * (y1 - y2));
    if (lineSize == 0)
        return Vector2(x1 - vec.x, y1 - vec.y);

    float u = ((vec.x - x1) * (x2 - x1)
             + (vec.y - y1) * (y2 - y1)) / (lineSize * lineSize);

    if (u < 0)
        return Vector2(x1 - vec.x, y1 - vec.y);
    else if (u > 1)
        return Vector2(x2 - vec.x, y2 - vec.y);
    else
    {
        float ix = x1 + u * (x2 - x1);
        float iy = y1 + u * (y2 - y1);
        return Vector2(ix - vec.x, iy - vec.y);
    }
}

Vector2 perp(const Vector2& vec)
{
  return Vector2(-vec.y, vec.x);
}

float dot(const Vector2& vec1, const Vector2& vec2)
{
  return vec1.x * vec2.x + vec1.y * vec2.y;
}

//TODO float Vector2::projectionCoeff(const Vector2* vec) const;
//TODO Vector2* Vector2::projection(const Vector2* vec) const;