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OgreEllipsoidEmitter.cpp

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00001 /*
00002 -----------------------------------------------------------------------------
00003 This source file is part of OGRE
00004     (Object-oriented Graphics Rendering Engine)
00005 For the latest info, see http://www.ogre3d.org/
00006 
00007 Copyright ) 2002 Tels <http://bloodgate.com> based on BoxEmitter
00008 Also see acknowledgements in Readme.html
00009 
00010 This program is free software; you can redistribute it and/or modify it under
00011 the terms of the GNU Lesser General Public License as published by the Free Software
00012 Foundation; either version 2 of the License, or (at your option) any later
00013 version.
00014 
00015 This program is distributed in the hope that it will be useful, but WITHOUT
00016 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
00017 FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
00018 
00019 You should have received a copy of the GNU Lesser General Public License along with
00020 this program; if not, write to the Free Software Foundation, Inc., 59 Temple
00021 Place - Suite 330, Boston, MA 02111-1307, USA, or go to
00022 http://www.gnu.org/copyleft/lesser.txt.
00023 -----------------------------------------------------------------------------
00024 */
00025 #include "OgreEllipsoidEmitter.h"
00026 #include "OgreParticle.h"
00027 #include "OgreException.h"
00028 #include "OgreStringConverter.h"
00029 
00030 
00031 /* Implements an Emitter whose emitting points all lie inside an ellipsoid.
00032    See <http://mathworld.wolfram.com/Ellipsoid.html> for mathematical details.
00033 
00034   If the lengths of two axes of an ellipsoid are the same, the figure is
00035   called a 'spheroid' (depending on whether c < a or c > a, an 'oblate
00036   spheroid' or 'prolate spheroid', respectively), and if all three are the
00037   same, it is a 'sphere' (ball).
00038 */
00039 
00040 namespace Ogre {
00041 
00042 
00043     //-----------------------------------------------------------------------
00044     EllipsoidEmitter::EllipsoidEmitter()
00045     {
00046         initDefaults("Ellipsoid");
00047     }
00048     //-----------------------------------------------------------------------
00049     void EllipsoidEmitter::_initParticle(Particle* pParticle)
00050     {
00051         Real x, y, z;
00052 
00053         // Call superclass
00054         AreaEmitter::_initParticle(pParticle);
00055         // First we create a random point inside a bounding sphere with a
00056         // radius of 1 (this is easy to do). The distance of the point from
00057         // 0,0,0 must be <= 1 (== 1 means on the surface and we count this as
00058         // inside, too).
00059 
00060         while (true)
00061         {
00062             // three random values for one random point in 3D space
00063 
00064             x = Math::SymmetricRandom();
00065             y = Math::SymmetricRandom();
00066             z = Math::SymmetricRandom();
00067 
00068             // the distance of x,y,z from 0,0,0 is sqrt(x*x+y*y+z*z), but
00069             // as usual we can omit the sqrt(), since sqrt(1) == 1 and we
00070             // use the 1 as boundary:
00071             if ( x*x + y*y + z*z <= 1)
00072                 {
00073                         break;          // found one valid point inside
00074                 }
00075         }       
00076 
00077         // scale the found point to the ellipsoid's size and move it
00078         // relatively to the center of the emitter point
00079 
00080         pParticle->mPosition = mPosition + 
00081          + x * mXRange + y * mYRange + z * mZRange;
00082 
00083         // Generate complex data by reference
00084         genEmissionColour(pParticle->mColour);
00085         genEmissionDirection(pParticle->mDirection);
00086         genEmissionVelocity(pParticle->mDirection);
00087 
00088         // Generate simpler data
00089         pParticle->mTimeToLive = pParticle->mTotalTimeToLive = genEmissionTTL();
00090         
00091     }
00092 
00093 }
00094 
00095 

Copyright © 2002-2003 by The OGRE Team
Last modified Fri May 14 23:22:07 2004