source: downloads/OgreMain/src/OgrePolygon.cpp @ 3

/*
-----------------------------------------------------------------------------
This source file is part of OGRE
(Object-oriented Graphics Rendering Engine)
For the latest info, see http://www.ogre3d.org/

Copyright (c) 2000-2006 Torus Knot Software Ltd
Copyright (c) 2006 Matthias Fink, netAllied GmbH <matthias.fink@web.de>                                                         
Also see acknowledgements in Readme.html

This program is free software; you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License as published by the Free Software
Foundation; either version 2 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 Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with
this program; if not, write to the Free Software Foundation, Inc., 59 Temple
Place - Suite 330, Boston, MA 02111-1307, USA, or go to
http://www.gnu.org/copyleft/lesser.txt.

You may alternatively use this source under the terms of a specific version of
the OGRE Unrestricted License provided you have obtained such a license from
Torus Knot Software Ltd.
-----------------------------------------------------------------------------
*/
#include "OgreStableHeaders.h"
#include "OgrePolygon.h"
#include "OgreException.h"
#include "OgreVector3.h"

namespace Ogre
{

        //-----------------------------------------------------------------------
        Polygon::Polygon()
        : mNormal( Vector3::ZERO )
        , mIsNormalSet(false)
        {
                // reserve space for 6 vertices to reduce allocation cost
                mVertexList.reserve(6);
        }
        //-----------------------------------------------------------------------
        Polygon::~Polygon()
        {
        }
        //-----------------------------------------------------------------------
        Polygon::Polygon( const Polygon& cpy )
        {
                mVertexList = cpy.mVertexList;
                mNormal = cpy.mNormal;
                mIsNormalSet = cpy.mIsNormalSet;
        }
        //-----------------------------------------------------------------------
        void Polygon::insertVertex(const Vector3& vdata, size_t vertex )
        {
                // TODO: optional: check planarity
                OgreAssert(vertex <= getVertexCount(), "Insert position out of range" );

                VertexList::iterator it = mVertexList.begin();

                std::advance(it, vertex);
                mVertexList.insert(it, vdata);

        }
        //-----------------------------------------------------------------------
        void Polygon::insertVertex(const Vector3& vdata)
        {
                mVertexList.push_back(vdata);
        }
        //-----------------------------------------------------------------------
        const Vector3& Polygon::getVertex( size_t vertex ) const
        {
                OgreAssert(vertex < getVertexCount(), "Search position out of range");

                return mVertexList[vertex];
        }
        //-----------------------------------------------------------------------
        void Polygon::setVertex(const Vector3& vdata, size_t vertex )
        {
                // TODO: optional: check planarity
                OgreAssert(vertex < getVertexCount(), "Search position out of range" );

                // set new vertex
                mVertexList[ vertex ] = vdata;
        }
        //-----------------------------------------------------------------------
        void Polygon::removeDuplicates( void )
        {
                for ( size_t i = 0; i < getVertexCount(); ++i )
                {
                        const Vector3& a = getVertex( i );
                        const Vector3& b = getVertex( (i + 1)%getVertexCount() );

                        if (a.positionEquals(b))
                        {
                                deleteVertex(i);
                                --i;
                        }
                }
        }
        //-----------------------------------------------------------------------
        size_t Polygon::getVertexCount( void ) const
        {
                return mVertexList.size();
        }
        //-----------------------------------------------------------------------
        const Vector3& Polygon::getNormal( void )
        {
                OgreAssert( getVertexCount() >= 3, "Insufficient vertex count!" );

                updateNormal();

                return mNormal;
        }
        //-----------------------------------------------------------------------
        void Polygon::updateNormal( void )
        {
                OgreAssert( getVertexCount() >= 3, "Insufficient vertex count!" );

                if (mIsNormalSet)
                        return;

                // vertex order is ccw
                const Vector3& a = getVertex( 0 );
                const Vector3& b = getVertex( 1 );
                const Vector3& c = getVertex( 2 );

                // used method: Newell
                mNormal.x = 0.5f * ( (a.y - b.y) * (a.z + b.z) +
                                                           (b.y - c.y) * (b.z + c.z) + 
                                                           (c.y - a.y) * (c.z + a.z));

                mNormal.y = 0.5f * ( (a.z - b.z) * (a.x + b.x) +
                                                           (b.z - c.z) * (b.x + c.x) + 
                                                           (c.z - a.z) * (c.x + a.x));

                mNormal.z = 0.5f * ( (a.x - b.x) * (a.y + b.y) +
                                                           (b.x - c.x) * (b.y + c.y) + 
                                                           (c.x - a.x) * (c.y + a.y));

                mNormal.normalise();

                mIsNormalSet = true;

        }
        //-----------------------------------------------------------------------
        void Polygon::deleteVertex( size_t vertex )
        {
                OgreAssert( vertex < getVertexCount(), "Search position out of range" );

                VertexList::iterator it = mVertexList.begin();
                std::advance(it, vertex);

                mVertexList.erase( it );
        }
        //-----------------------------------------------------------------------
        void Polygon::storeEdges( Polygon::EdgeMap *edgeMap ) const
        {
                OgreAssert( edgeMap != NULL, "EdgeMap ptr is NULL" );

                size_t vertexCount = getVertexCount();

                for ( size_t i = 0; i < vertexCount; ++i )
                {
                        edgeMap->insert( Edge( getVertex( i ), getVertex( ( i + 1 ) % vertexCount ) ) );
                }
        }
        //-----------------------------------------------------------------------
        void Polygon::reset( void )
        {
                // could use swap() to free memory here, but assume most may be reused so avoid realloc
                mVertexList.clear();

                mIsNormalSet = false;
        }
        //-----------------------------------------------------------------------
        bool Polygon::operator == (const Polygon& rhs) const
        {
                if ( getVertexCount() != rhs.getVertexCount() )
                        return false;

                // Compare vertices. They may differ in its starting position.
                // find start
                size_t start;
                bool foundStart = false;
                for (size_t i = 0; i < getVertexCount(); ++i )
                {       
                        if (getVertex(0).positionEquals(rhs.getVertex(i)))
                        {
                                start = i;
                                foundStart = true;
                                break;
                        }
                }

                if (!foundStart)
                        return false;

                for (size_t i = 0; i < getVertexCount(); ++i )
                {
                        const Vector3& vA = getVertex( i );
                        const Vector3& vB = rhs.getVertex( ( i + start) % getVertexCount() );

                        if (!vA.positionEquals(vB))
                                return false;
                }

                return true;
        }
        //-----------------------------------------------------------------------
        std::ostream& operator<< ( std::ostream& strm, const Polygon& poly )
        {
                strm << "NUM VERTICES: " << poly.getVertexCount() << std::endl;

                for (size_t j = 0; j < poly.getVertexCount(); ++j )
                {
                        strm << "VERTEX " << j << ": " << poly.getVertex( j ) << std::endl;
                }

                return strm;
        }
        //-----------------------------------------------------------------------
}