khanat-code-old/code/nel/src/pacs/vector_2s.cpp

61 lines
1.7 KiB
C++

// NeL - MMORPG Framework <http://dev.ryzom.com/projects/nel/>
// Copyright (C) 2010 Winch Gate Property Limited
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as
// published by the Free Software Foundation, either version 3 of the
// License, or (at your option) any later version.
//
// This program 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 Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
#include "stdpacs.h"
#include "vector_2s.h"
namespace NLPACS {
// Test if 2 segments intersects
bool CVector2s::intersect(const CVector2s& a0, const CVector2s& a1, const CVector2s& b0, const CVector2s& b1, double* pa, double* pb)
{
double a0x = CVector2s::unpack(a0.x);
double a0y = CVector2s::unpack(a0.y);
double a1x = CVector2s::unpack(a1.x);
double a1y = CVector2s::unpack(a1.y);
double b0x = CVector2s::unpack(b0.x);
double b0y = CVector2s::unpack(b0.y);
double b1x = CVector2s::unpack(b1.x);
double b1y = CVector2s::unpack(b1.y);
double ax = +(a1x-a0x);
double ay = +(a1y-a0y);
double bx = +(b1x-b0x);
double by = +(b1y-b0y);
double cx = +(b0x-a0x);
double cy = +(b0y-a0y);
double d = -ax*by + ay*bx;
if (d == 0.0)
return false;
double a = (bx*cy - by*cx) / d;
double b = (ax*cy - ay*cx) / d;
if (pa != NULL)
*pa = a;
if (pb != NULL)
*pb = b;
return d != 0.0 && a >= 0.0 && a <= 1.0 && b >= 0.0 && b <= 1.0;
}
} // NLPACS