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00001 
00007 /* Copyright, 2000-2002 Nevrax Ltd.
00008  *
00009  * This file is part of NEVRAX NEL.
00010  * NEVRAX NEL is free software; you can redistribute it and/or modify
00011  * it under the terms of the GNU General Public License as published by
00012  * the Free Software Foundation; either version 2, or (at your option)
00013  * any later version.
00014 
00015  * NEVRAX NEL is distributed in the hope that it will be useful, but
00016  * WITHOUT ANY WARRANTY; without even the implied warranty of
00017  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
00018  * General Public License for more details.
00019 
00020  * You should have received a copy of the GNU General Public License
00021  * along with NEVRAX NEL; see the file COPYING. If not, write to the
00022  * Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
00023  * MA 02111-1307, USA.
00024  */
00025 
00026 #ifndef NL_MRM_LEVEL_DETAIL_H
00027 #define NL_MRM_LEVEL_DETAIL_H
00028 
00029 #include "nel/misc/types_nl.h"
00030 #include "nel/misc/common.h"
00031 
00032 
00033 namespace NL3D 
00034 {
00035 
00036 
00037 // ***************************************************************************
00038 /* This is used to have correct max Polygon count setuped. This suppose that MRM.NumLod==10
00039         Hence, a mean value of 0.5*1/10 is used
00040 */
00041 #define NL3D_MRM_LD_SHIFT_POLY_COUNT    0.05f
00042 
00043 
00044 // ***************************************************************************
00051 class CMRMLevelDetail
00052 {
00053 public:
00054 
00056         uint32                          MinFaceUsed;
00058         uint32                          MaxFaceUsed;
00059 
00061         float                           DistanceFinest;
00063         float                           DistanceMiddle;
00065         float                           DistanceCoarsest;
00066 
00068         float                           OODistanceDelta;
00069         float                           DistancePow;
00070 
00071 public:
00073         CMRMLevelDetail() {}
00074 
00076         void                            compileDistanceSetup();
00077 
00079         float                           getLevelDetailFromDist(float dist);
00080 
00082         float                           getNumTriangles (float dist)
00083         {
00084                 // return the lod detail [0,1].
00085                 float   ld= getLevelDetailFromDist(dist);
00086                 // return in nb face.
00087                 if(ld<=0)
00088                         return (float)MinFaceUsed;
00089                 else
00090                 {
00091                         /* over-estimate the number of poly rendered 
00092                                 because this is always the higher Lod which is rendered, geomorphing to the coarser one.
00093                                 NB: still need to over-estimate if ld==1, because getLevelDetailFromPolyCount() remove the shift...
00094                         */
00095                         ld+= NL3D_MRM_LD_SHIFT_POLY_COUNT;
00096                         return MinFaceUsed + ld * (MaxFaceUsed - MinFaceUsed);
00097                 }
00098         }
00099 
00101         float                           getLevelDetailFromPolyCount(float polygonCount)
00102         {
00103                 float   ld;
00104                 if(MaxFaceUsed > MinFaceUsed)
00105                 {
00106                         // compute the level of detail we want.
00107                         ld= (polygonCount - MinFaceUsed) / (MaxFaceUsed - MinFaceUsed);
00108                         /* remove the value added in getNumTriangles(). For the same reason:
00109                                 this is always the higher Lod which is rendered, geomorphing to the coarser one.
00110                                 Hence we must degrade a bit.
00111                                 NB: if polygonCount==MinFaceUsed, then we have here ld= -NL3D_MRM_LD_SHIFT_POLY_COUNT (ie -0.05f)
00112                                 but it is clamped below
00113                         */
00114                         ld-= NL3D_MRM_LD_SHIFT_POLY_COUNT;
00115                         NLMISC::clamp(ld, 0, 1);
00116                 }
00117                 else
00118                         ld= 1;
00119 
00120                 return ld;
00121         }
00122 
00123 };
00124 
00125 
00126 } // NL3D
00127 
00128 
00129 #endif // NL_MRM_LEVEL_DETAIL_H
00130 
00131 /* End of mrm_level_detail.h */