86 lines
2.2 KiB
C++
86 lines
2.2 KiB
C++
/* Copyright (C) 2011 Wildfire Games.
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* This file is part of 0 A.D.
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*
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* 0 A.D. is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 2 of the License, or
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* (at your option) any later version.
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*
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* 0 A.D. is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with 0 A.D. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "precompiled.h"
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#include "BoundingBoxOriented.h"
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#include "maths/BoundingBoxAligned.h"
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#include <float.h>
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const CBoundingBoxOriented CBoundingBoxOriented::EMPTY = CBoundingBoxOriented();
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CBoundingBoxOriented::CBoundingBoxOriented(const CBoundingBoxAligned& bound)
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{
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if (bound.IsEmpty())
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{
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SetEmpty();
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}
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else
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{
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bound.GetCentre(m_Center);
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// the axes of an AABB are the world-space axes
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m_Basis[0].X = 1.f; m_Basis[0].Y = 0.f; m_Basis[0].Z = 0.f;
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m_Basis[1].X = 0.f; m_Basis[1].Y = 1.f; m_Basis[1].Z = 0.f;
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m_Basis[2].X = 0.f; m_Basis[2].Y = 0.f; m_Basis[2].Z = 1.f;
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// element-wise division by two to get half sizes (remember, [1] and [0] are the max and min coord points)
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m_HalfSizes = (bound[1] - bound[0]) * 0.5f;
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}
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}
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bool CBoundingBoxOriented::RayIntersect(const CVector3D& origin, const CVector3D& dir, float& tMin_out, float& tMax_out) const
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{
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// See Real-Time Rendering, Third Edition, p. 743
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float tMin = -FLT_MAX;
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float tMax = FLT_MAX;
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CVector3D p = m_Center - origin;
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for (int i = 0; i < 3; ++i)
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{
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float e = m_Basis[i].Dot(p);
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float f = m_Basis[i].Dot(dir);
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if(fabs(f) > 1e-10f)
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{
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float invF = 1.f/f;
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float t1 = (e + m_HalfSizes[i]) * invF;
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float t2 = (e - m_HalfSizes[i]) * invF;
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if (t1 > t2)
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{
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float tmp = t1;
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t1 = t2;
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t2 = tmp;
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}
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if (t1 > tMin) tMin = t1;
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if (t2 < tMax) tMax = t2;
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if (tMin > tMax) return false;
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if (tMax < 0) return false;
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}
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else
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{
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if(-e - m_HalfSizes[i] > 0 || -e + m_HalfSizes[i] < 0) return false;
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}
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}
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tMin_out = tMin;
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tMax_out = tMax;
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return true;
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} |