Frustum.h

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/* Copyright (C) 2021 Wildfire Games.
 * This file is part of 0 A.D.
 *
 * 0 A.D. 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 2 of the License, or
 * (at your option) any later version.
 *
 * 0 A.D. 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 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
 */

/*
 * CFrustum is a collection of planes which define a viewing space.
 */

/*
Usually associated with the camera, there are 6 planes which define the
view pyramid. But we allow more planes per frustum which may be used for
portal rendering, where a portal may have 3 or more edges.
*/

#ifndef INCLUDED_FRUSTUM
#define INCLUDED_FRUSTUM

#include "maths/Plane.h"

class CBoundingBoxAligned;
class CMatrix3D;

class CFrustum
{
public:
    CFrustum();
    ~CFrustum();

    // Set the number of planes to use for calculations. This is clamped to
    // [0, MAX_NUM_FRUSTUM_PLANES].
    void SetNumPlanes(size_t num);

    size_t GetNumPlanes() const { return m_NumPlanes; }

    void AddPlane(const CPlane& plane);

    void Transform(const CMatrix3D& m);

    // The following methods return true if the shape is
    // partially or completely in front of the frustum planes.
    bool IsPointVisible(const CVector3D& point) const;
    bool DoesSegmentIntersect(const CVector3D& start, const CVector3D& end) const;
    bool IsSphereVisible(const CVector3D& center, float radius) const;
    bool IsBoxVisible(const CVector3D& position, const CBoundingBoxAligned& bounds) const;
    bool IsBoxVisible(const CBoundingBoxAligned& bounds) const;

    CPlane& operator[](size_t idx) { return m_Planes[idx]; }
    const CPlane& operator[](size_t idx) const { return m_Planes[idx]; }

private:
    static const size_t MAX_NUM_FRUSTUM_PLANES = 10;

    CPlane m_Planes[MAX_NUM_FRUSTUM_PLANES];
    size_t m_NumPlanes;
};

#endif // INCLUDED_FRUSTUM