o3de/Code/CryEngine/RenderDll/Common/RendElements/Utils/PolygonMath2D.h

/*
* All or portions of this file Copyright (c) Amazon.com, Inc. or its affiliates or
* its licensors.
*
* For complete copyright and license terms please see the LICENSE at the root of this
* distribution (the "License"). All use of this software is governed by the License,
* or, if provided, by the license below or the license accompanying this file. Do not
* remove or modify any license notices. This file is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
*
*/
// Original file Copyright Crytek GMBH or its affiliates, used under license.

#ifndef CRYINCLUDE_CRYENGINE_RENDERDLL_COMMON_RENDELEMENTS_UTILS_POLYGONMATH2D_H
#define CRYINCLUDE_CRYENGINE_RENDERDLL_COMMON_RENDELEMENTS_UTILS_POLYGONMATH2D_H
#pragma once

#include "CryFixedArray.h"

//==================================================================================================
// Name: FixedPodArray
// Desc: Extension of CryFixedArray to add useful functionality
// Note: This should be promoted into CryFixedArray in the long term
// Author: Chris Bunner
//==================================================================================================
template <class T, unsigned int N>
class FixedPodArray
    : public CryFixedArray<T, N>
{
    typedef CryFixedArray<T, N> CFA;

public:
    ILINE void resize(const uint size)
    {
        if (size <= N)
        {
            CFA::m_curSize[0] = size;
        }
        else
        {
            CryLogAlways("FixedPodArray::resize() failing as size too large - NOT resizing array");
            CRY_ASSERT_MESSAGE(0, "FixedPodArray::resize() failing as size too large - NOT resizing array");
        }
    }

    ILINE void erase(const uint index, const uint count = 1)
    {
        const uint size = CFA::m_curSize[0];

        if (index == size - count)
        {
            // Simple remove
            CFA::m_curSize[0] -= count;
        }
        else if (index + count < size)
        {
            // Shuffle set of elements along
            const uint range = size - (index + count);
            memmove(&CFA::at(index), &CFA::at(index + count), sizeof(T) * range);

            CFA::m_curSize[0] -= count;
        }
        else
        {
            CryLogAlways("FixedPodArray::erase() failing as element range invalid - NOT removing element");
            CRY_ASSERT_MESSAGE(0, "FixedPodArray::erase() failing as element range invalid - NOT removing element");
        }
    }

    ILINE void insert_before(const T& elem, const uint index)
    {
        const uint size = CFA::m_curSize[0];

        if (index < size && size < N)
        {
            // Shuffle set of elements along
            const uint count = size - index;
            memmove(&CFA::at(index + 1), &CFA::at(index), sizeof(T) * count);

            // Add new element
            memcpy(&CFA::at(index), &elem, sizeof(T));
            ++CFA::m_curSize[0];
        }
        else
        {
            CryLogAlways("FixedPodArray::insert_before() failing as element index invalid - NOT inserting element");
            CRY_ASSERT_MESSAGE(0, "FixedPodArray::insert_before() failing as element index invalid - NOT inserting element");
        }
    }

    ILINE int   find(const T& elem)
    {
        const uint size = CFA::m_curSize[0];
        const int invalid = -1;

        int index = invalid;

        for (uint i = 0; i < size; ++i)
        {
            if (CFA::at(i) == elem)
            {
                index = i;
                break;
            }
        }

        return index;
    }
};

//==================================================================================================
// Name: PolygonMath2D
// Desc: Polygon math helper functions optimized for breakable glass sim
// Note: Functions often assume clockwise polygon point order
// Author: Chris Bunner
//==================================================================================================

// Common polygon array types
#define POLY_ARRAY_SIZE         45

typedef FixedPodArray<Vec2, POLY_ARRAY_SIZE>                    TPolygonArray;
typedef FixedPodArray<int, POLY_ARRAY_SIZE>                     TPolyIndexArray;

// 2D triangle helpers
bool        PointInTriangle2D(const Vec2& pt, const Vec2& a, const Vec2& b, const Vec2& c);
bool        TriangleIsConvex2D(const Vec2& a, const Vec2& b, const Vec2& c);

// 2D intersection helpers
int         LineCircleIntersect2D(const Vec2& pt0, const Vec2& pt1, const Vec2& center, const float radiusSq, float& intersectA, float& intersectB);

// 2D polygon helpers
bool        PointInPolygon2D(const Vec2& pt, const Vec2* pPolygon, const int numPts);

float       CalculatePolygonArea2D(const Vec2* pPolygon, const int numPts);
Vec2        CalculatePolygonBounds2D(const Vec2* pPolygon, const int numPts);
Vec2        CalculatePolygonCenter2D(const Vec2* pPolygon, const int numPts);
bool        CalculatePolygonSharedPerimeter2D(const Vec2* pPolygonA, const int numPtsA, const Vec2* pPolygonB, const int numPtsB, float& connectionA, float& connectionB);

void        TriangulatePolygon2D(const Vec2* pPolygon, const int numPolyPts, PodArray<Vec2>* pVertices, PodArray<uint8>* pIndices);
void        SplitPolygonAroundPoint(TPolygonArray& outline, const Vec2& splitPt, const float splitRadius, TPolygonArray& splitInnerOutline);
void        SplitPolygonAroundPoint(PodArray<Vec2>& outline, const Vec2& splitPt, const float splitRadius, TPolygonArray& splitInnerOutline);

// Helper with result enum
enum EPolygonInCircle2D
{
    EPolygonInCircle2D_Inside = 0,
    EPolygonInCircle2D_Outside,
    EPolygonInCircle2D_Overlap
};

EPolygonInCircle2D PolygonInCircle2D(const Vec2& center, const float radius, const Vec2* pPolygon, const int numPts);

#endif // _POLYGON_MATH_2D_