76 lines
1.8 KiB
C++
76 lines
1.8 KiB
C++
/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2003 Robert Osfield
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*
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* This library is open source and may be redistributed and/or modified under
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* the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or
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* (at your option) any later version. The full license is in LICENSE file
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* included with this distribution, and on the openscenegraph.org website.
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*
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* This library 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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* OpenSceneGraph Public License for more details.
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*/
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#include <osg/Shape>
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#include <algorithm>
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using namespace osg;
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Shape::~Shape()
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{
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}
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HeightField::~HeightField()
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{
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}
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void HeightField::allocate(unsigned int numColumns,unsigned int numRows)
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{
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if (_columns!=numColumns || _rows!=numRows)
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{
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_heights.resize(numColumns*numRows);
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}
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_columns=numColumns;
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_rows=numRows;
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}
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Vec3 HeightField::getNormal(unsigned int c,unsigned int r) const
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{
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// four point normal generation.
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float dz_dx;
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if (c==0)
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{
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dz_dx = (getHeight(c+1,r)-getHeight(c,r))/getXInterval();
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}
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else if (c==getNumColumns()-1)
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{
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dz_dx = (getHeight(c,r)-getHeight(c-1,r))/getXInterval();
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}
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else // assume 0<c<_numColumns-1
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{
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dz_dx = 0.5f*(getHeight(c+1,r)-getHeight(c-1,r))/getXInterval();
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}
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float dz_dy;
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if (r==0)
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{
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dz_dy = (getHeight(c,r+1)-getHeight(c,r))/getYInterval();
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}
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else if (r==getNumRows()-1)
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{
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dz_dy = (getHeight(c,r)-getHeight(c,r-1))/getYInterval();
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}
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else // assume 0<r<_numRows-1
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{
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dz_dy = 0.5f*(getHeight(c,r+1)-getHeight(c,r-1))/getYInterval();
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}
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Vec3 normal(-dz_dx,-dz_dy,1.0f);
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normal.normalize();
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return normal;
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}
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