/*****************************************************************************************
 *                                                                                       *
 * OpenSpace                                                                             *
 *                                                                                       *
 * Copyright (c) 2014-2017                                                               *
 *                                                                                       *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this  *
 * software and associated documentation files (the "Software"), to deal in the Software *
 * without restriction, including without limitation the rights to use, copy, modify,    *
 * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to    *
 * permit persons to whom the Software is furnished to do so, subject to the following   *
 * conditions:                                                                           *
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 * The above copyright notice and this permission notice shall be included in all copies *
 * or substantial portions of the Software.                                              *
 *                                                                                       *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,   *
 * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A         *
 * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT    *
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 * OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                                         *
 ****************************************************************************************/

#ifndef __OPENSPACE_MODULE_GLOBEBROWSING___CONVEX_HULL___H__
#define __OPENSPACE_MODULE_GLOBEBROWSING___CONVEX_HULL___H__

#include <modules/globebrowsing/geometry/aabb.h>

#include <stack>
#include <vector>

#include <ghoul/glm.h>

namespace openspace {
namespace globebrowsing {

// Implementation based on 
// http://www.sanfoundry.com/cpp-program-implement-graham-scan-algorithm-find-convex-hull/

class ConvexHull2 {
public: 
    static ConvexHull2 grahamScan_NOT_THREAD_SAFE(std::vector<glm::vec2>& points,
        int yMinIndex = -1);

    const std::vector<glm::vec2> points() const;

    bool intersects(const ConvexHull2& o) const;

    AABB1 projectedRegion(glm::vec2 direction) const;
    
private:
    bool hasPerpendicularLineWhereProjectedPointsOverlap(const ConvexHull2& other) const;

    static int compare(const void* vp1, const void* vp2);

    static glm::vec2 oneBelowTop(std::stack<glm::vec2>&);
    static void swap(glm::vec2& p1, glm::vec2& p2);

    // returns 0 = colinear, 1 = clockwise, 2 = counterclockwise
    static int orientation(const glm::vec2& p, const glm::vec2& q, const glm::vec2& r);
    static float dist(const glm::vec2& p1, const glm::vec2& p2);

private:
    static glm::vec2 p0;
    std::vector<glm::vec2> _points;
};

} // namespace globebrowsing   
} // namespace openspace

#endif // __OPENSPACE_MODULE_GLOBEBROWSING___CONVEX_HULL___H__