F:/My Projects/LSEngine/Modules/LSPhysicsLib/Src/Intersections/LSPIntersect.h

#ifndef __LSP_INTERSECT_H__
#define __LSP_INTERSECT_H__

#include "../LSPPhysicsLib.h"
#include "Plane/LSMPlane3.h"

namespace lsp {

        class CIntersect {
                // All is public.  This class has no secrets.
        public :
                // == Functions.
                template <typename _tType, typename _tPlaneType, typename _tVecType>
                static LSE_INLINE LSBOOL LSE_CALL                                               ThreePlanes( const _tPlaneType &_pP0, const _tPlaneType &_pP1, const _tPlaneType &_pP2, _tVecType &_vRet ) {
                        _tVecType vU = _pP1.n % _pP2.n;

                        _tType fDenom = _pP0.n * vU;
                        if ( CMathLib::AbsT( fDenom ) <= static_cast<_tType>(LSM_REAL_EPSILON) ) { return false; }

                        _vRet = (vU * _pP0.dist + _pP0.n.Cross( _pP1.n * _pP2.dist - _pP2.n * _pP1.dist )) / fDenom;

                        return true;
                }

                template <typename _tType, typename _tPlaneType, typename _tRayType>
                static LSE_INLINE LSBOOL LSE_CALL                                               TwoPlanes( const _tPlaneType &_pP0, const _tPlaneType &_pP1, _tRayType &_rRay ) {
                        // Direction of the intersection.
                        _rRay.dir = _pP0.n % _pP1.n;

                        // If it is (near) 0, the planes are parallel (and separated) or coincident and not considered
                        //      intersecting.
                        if ( _rRay.dir.Dot( _rRay.dir ) < static_cast<_tType>(LSM_REAL_EPSILON) ) { return false; }

                        // Finish the ray by computing a point on the intersection line.
                        _rRay.p = ((_pP1.n * _pP0.dist) - (_pP0.n * _pP1.dist)) % _rRay.dir;
                        return true;
                }

                template <typename _tType, typename _tVecType, typename _tPlaneType>
                static LSE_INLINE LSBOOL LSE_CALL                                               LineSegPlane( const _tVecType &_vStart, const _tVecType &_vEnd, const _tPlaneType &_pPlane, _tType &_fT, _tVecType &_vRet ) {
                        _tVecType vAb = _vEnd - _vStart;
                        _tType fDenom = _pPlane.n.Dot( vAb );
                        if ( fDenom == static_cast<_tType>(0.0) ) {
                                // Coplanar.
                                return false;
                        }
                        _fT = (_pPlane.dist - _pPlane.n.Dot( _vStart )) / fDenom;
                        if ( _fT >= static_cast<_tType>(0.0) && _fT <= static_cast<_tType>(1.0) ) {
                                _vRet = _vStart + vAb * _fT;
                                return true;
                        }
                        return false;
                }

                template <typename _tType, typename _tVecType, typename _tPlaneType>
                static LSE_INLINE LSVOID LSE_CALL                                               LineSegPlaneFast( const _tVecType &_vStart, const _tVecType &_vEnd, const _tPlaneType &_pPlane, _tVecType &_vRet ) {
                        _tVecType vAb = _vEnd - _vStart;
                        _tType fT = (_pPlane.dist - _pPlane.n.Dot( _vStart )) / _pPlane.n.Dot( vAb );
                        _vRet = _vStart + vAb * fT;
                }

        };


        // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
        // DEFINITIONS
        // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
        // == Functions.

}       // namespace lsp

#endif  // __LSP_INTERSECT_H__