Panda3D
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00001 // Filename: heightfieldTesselator.h 00002 // Created by: jyelon (17jul06) 00003 // 00004 //////////////////////////////////////////////////////////////////// 00005 // 00006 // PANDA 3D SOFTWARE 00007 // Copyright (c) Carnegie Mellon University. All rights reserved. 00008 // 00009 // All use of this software is subject to the terms of the revised BSD 00010 // license. You should have received a copy of this license along 00011 // with this source code in a file named "LICENSE." 00012 // 00013 //////////////////////////////////////////////////////////////////// 00014 00015 #ifndef HEIGHTFIELDTESSELATOR_H 00016 #define HEIGHTFIELDTESSELATOR_H 00017 00018 #include "pandabase.h" 00019 00020 #include "luse.h" 00021 #include "pandaNode.h" 00022 #include "pointerTo.h" 00023 #include "namable.h" 00024 #include "pnmImage.h" 00025 #include "geom.h" 00026 #include "geomTristrips.h" 00027 #include "geomTriangles.h" 00028 #include "geomVertexWriter.h" 00029 #include "geomVertexFormat.h" 00030 #include "nodePath.h" 00031 00032 //////////////////////////////////////////////////////////////////// 00033 // Class : HeightfieldTesselator 00034 // Description : Converts a height field in the form of a greyscale 00035 // image into a scene consisting of a number of GeomNodes. 00036 // 00037 // The tesselation uses an LOD algorithm. You 00038 // supply a "focal point" (X,Y) which tells the 00039 // tesselator where the bulk of the detail should 00040 // be concentrated. The intent is that as the player 00041 // walks around the terrain, you should occasionally 00042 // move the focal point to wherever the player is. 00043 // You should not move the focal point every frame: 00044 // tesselation is not that fast. Also, changing the 00045 // focal point may cause popping, so it is best to 00046 // minimize the number of changes. There are a number 00047 // of parameters that you can use to control tesselation, 00048 // such as a target polygon count, and a visibility 00049 // radius. 00050 // 00051 // The heightfield needs to be a multiple of 128 pixels 00052 // in each dimension. It does not need to be square, 00053 // and it does not need to be a power of two. For 00054 // example, a 384 x 640 heightfield is fine. 00055 // Be aware that tesselation time is proportional to 00056 // heightfield area, so if you plan to use a size larger 00057 // than about 512x512, it may be desirable to benchmark. 00058 // 00059 // Altering parameters, such as the poly count, the 00060 // view radius, or the focal point, does not alter any 00061 // GeomNodes already generated. Parameter changes only 00062 // affect subsequently-generated GeomNodes. It is 00063 // possible to cache many different tesselations of the 00064 // same terrain. 00065 // 00066 //////////////////////////////////////////////////////////////////// 00067 00068 class EXPCL_PANDA_GRUTIL HeightfieldTesselator : public Namable { 00069 PUBLISHED: 00070 INLINE HeightfieldTesselator(const string &name); 00071 INLINE ~HeightfieldTesselator(); 00072 00073 INLINE PNMImage &heightfield(); 00074 INLINE bool set_heightfield(const Filename &filename, PNMFileType *type = NULL); 00075 INLINE void set_poly_count(int n); 00076 INLINE void set_visibility_radius(int r); 00077 INLINE void set_focal_point(int x, int y); 00078 INLINE void set_horizontal_scale(double h); 00079 INLINE void set_vertical_scale(double v); 00080 INLINE void set_max_triangles(int n); 00081 00082 double get_elevation(double x, double y); 00083 00084 NodePath generate(); 00085 00086 private: 00087 00088 // These are initialized during the first 'generate' 00089 int _radii[16]; 00090 bool _radii_calculated; 00091 00092 // These are only valid during the generate process. 00093 int *_triangle_totals; 00094 int *_vertex_index; 00095 int *_dirty_vertices; 00096 00097 // These are only valid when a geom is open. 00098 int _next_index; 00099 int _last_vertex_a; 00100 int _last_vertex_b; 00101 PT(GeomVertexData) _vdata; 00102 GeomVertexWriter *_vertex_writer; 00103 GeomVertexWriter *_normal_writer; 00104 PT(GeomTriangles) _triangles; 00105 00106 INLINE bool subdivide(int scale, int x, int y); 00107 void calculate_radii(int scale); 00108 void generate_square(NodePath root, int scale, int x, int y, bool forceclose); 00109 int count_triangles(int scale, int x, int y); 00110 int get_vertex(int x, int y); 00111 void add_quad_to_strip(int v1, int v2, int v3, int v4); 00112 void add_quad(int v1, int v2, int v3, int v4); 00113 void fix_heightfield(int size); 00114 void open_geom(); 00115 void close_geom(NodePath root); 00116 00117 PNMImage _heightfield; 00118 int _poly_count; 00119 int _visibility_radius; 00120 int _focal_x; 00121 int _focal_y; 00122 double _horizontal_scale; 00123 double _vertical_scale; 00124 int _max_triangles; 00125 }; 00126 00127 #include "heightfieldTesselator.I" 00128 00129 #endif 00130