src/lib/vector.cpp

//
// AutoCoast: Automatic Coastline scenery generator for Flight Simulator
//
// Copyright (c) 2004, Takuya Murakami. 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 REGENTS 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
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// vector.hpp : 2D vector class

#include <math.h>
#include "vector.hpp"

// set vector between two gpc_vertex.
void Vector::set(gpc_vertex *f, gpc_vertex *t)
{
        if (t) {
                x = t->x - f->x;
                y = t->y - f->y;
        } else {
                x = f->x;
                y = f->y;
        }
}

Vector Vector::operator+ (const Vector &v) const
{
        Vector vv(x + v.x, y + v.y);
        return vv;
}

Vector Vector::operator- (const Vector &v) const
{
        Vector vv(x - v.x, y - v.y);
        return vv;
}

Vector Vector::operator* (double m) const
{
        Vector vv(x * m, y * m);
        return vv;
}

Vector Vector::operator/ (double m) const
{
        Vector vv(x / m, y / m);
        return vv;
}

// Normalize vector
Vector Vector::normalize(void) const
{
        double sz = sqrt(x * x + y * y);
        Vector vv(x / sz, y / sz);
        return vv;
}

// calculate innter product
double Vector::InnerProduct(const Vector &v) const
{
        return x * v.x + y * v.y;
}

// calculate outer product
double Vector::OuterProduct(const Vector &v) const
{
        return x * v.y - y * v.x;
}

// calculate angle between two vectors.
double Vector::Angle(const Vector &target) const
{
        Vector v1 = normalize();
        Vector v2 = target.normalize();

        double inp = v1.InnerProduct(v2);
        double deg = acos(inp);
        
        double oup = v1.OuterProduct(v2);
        if (oup < 0) {
                deg = -deg;
        }

        return deg;
}

        
        