source/3d/tracktype.cpp

   1 /* $Id$
   2
   3 This file is part of R²C²
   4 Copyright © 2010 Mikkosoft Productions, Mikko Rasa
   5 Distributed under the GPL
   6 */
   7
   8 #include <algorithm>
   9 #include <cmath>
  10 #include <msp/gl/technique.h>
  11 #include "catalogue.h"
  12 #include "tracktype.h"
  13
  14 using namespace std;
  15 using namespace Msp;
  16
  17 namespace {
  18
  19 bool compare_z(const R2C2::Point &p1, const R2C2::Point &p2)
  20 {
  21         return p1.z<p2.z;
  22 }
  23
  24 template<typename Iter>
  25 Iter graham_scan(Iter begin, Iter end)
  26 {
  27         // http://en.wikipedia.org/wiki/Graham_scan
  28
  29         // Find point with lowest X coordinate
  30         R2C2::Point lowest = *begin;
  31         for(Iter i=begin; i!=end; ++i)
  32                 if(i->x<lowest.x || (i->x==lowest.x && i->y>lowest.y))
  33                         lowest = *i;
  34
  35         // Compute tangents and sort points
  36         for(Iter i=begin; i!=end; ++i)
  37                 i->z = (i->x==lowest.x ? 1e5/(i->y-lowest.y-1) : (i->y-lowest.y)/(i->x-lowest.x));
  38         sort(begin, end, compare_z);
  39
  40         for(Iter k=begin, i=k++, j=k++;; )
  41         {
  42                 // Compute winding by cross product
  43                 float turn = (j->x-i->x)*(k->y-j->y) - (k->x-j->x)*(j->y-i->y);
  44
  45                 if(turn<1e-5)
  46                 {
  47                         // Right turn - throw the middle point away
  48                         // Special case for collinear vertices in the beginning
  49                         if(i==begin)
  50                                 j = k++;
  51                         else
  52                                 j = i--;
  53                 }
  54                 else
  55                 {
  56                         // Left turn - store the middle point and advance
  57                         if(++i!=j)
  58                                 *i = *j;
  59                         j = k++;
  60                 }
  61
  62                 // Cycle back to beginning and terminate after checking the last point
  63                 if(k==end)
  64                         k = begin;
  65                 else if(j==begin)
  66                         return ++i;
  67         }
  68 }
  69
  70 }
  71
  72 namespace R2C2 {
  73
  74 TrackType3D::TrackType3D(Catalogue3D &cat3d, const TrackType &tt):
  75         catalogue(cat3d),
  76         mesh((GL::NORMAL3, GL::TEXCOORD2, GL::VERTEX3))
  77 {
  78         const Catalogue &cat = cat3d.get_catalogue();
  79         const vector<TrackPart> &parts = tt.get_parts();
  80
  81         const Profile &ballast_profile = cat.get_ballast_profile();
  82         const Point &ballast_min = ballast_profile.get_min_coords();
  83         const Point &ballast_max = ballast_profile.get_max_coords();
  84         float ballast_h = ballast_max.y-ballast_min.y;
  85
  86         const Profile &rail_profile = cat.get_rail_profile();
  87         const Point &rail_min = rail_profile.get_min_coords();
  88         const Point &rail_max = rail_profile.get_max_coords();
  89         float rail_h = rail_max.y-rail_min.y;
  90
  91         float gauge = cat.get_gauge();
  92
  93         {
  94                 unsigned index = 0;
  95                 GL::MeshBuilder bld(mesh);
  96                 bld.texcoord(0.25, 0.5);
  97                 for(vector<TrackPart>::const_iterator i=parts.begin(); i!=parts.end(); ++i)
  98                         build_part(*i, ballast_profile, Point(0, -ballast_min.y), bld, index);
  99
 100                 bld.texcoord(0.75, 0.5);
 101                 float y = ballast_h-rail_min.y;
 102                 for(vector<TrackPart>::const_iterator i=parts.begin(); i!=parts.end(); ++i)
 103                         build_part(*i, rail_profile, Point(-gauge/2-rail_max.x, y), bld, index);
 104                 for(vector<TrackPart>::const_iterator i=parts.begin(); i!=parts.end(); ++i)
 105                         build_part(*i, rail_profile, Point(gauge/2-rail_min.x, y), bld, index);
 106         }
 107
 108         object.set_mesh(&mesh);
 109         object.set_technique(catalogue.get<GL::Technique>(cat.get_track_technique()));
 110
 111         unsigned paths = tt.get_paths();
 112         for(unsigned i=0; paths; ++i, paths>>=1)
 113         {
 114                 GL::Mesh *m = 0;
 115                 if(paths&1)
 116                 {
 117                         m = new GL::Mesh(GL::VERTEX3);
 118                         GL::MeshBuilder bld(*m);
 119                         unsigned index = 0;
 120                         for(vector<TrackPart>::const_iterator j=parts.begin(); j!=parts.end(); ++j)
 121                                 if(j->get_path()==i)
 122                                         build_part(*j, cat.get_path_profile(), Point(0, ballast_h+1.5*rail_h), bld, index);
 123                 }
 124                 path_meshes.push_back(m);
 125         }
 126
 127         min_z = max_z = border.front().z;
 128         for(vector<Point>::iterator i=border.begin(); i!=border.end(); ++i)
 129         {
 130                 min_z = min(min_z, i->z);
 131                 max_z = max(max_z, i->z);
 132         }
 133         border.erase(graham_scan(border.begin(), border.end()), border.end());
 134 }
 135
 136 TrackType3D::~TrackType3D()
 137 {
 138         for(vector<GL::Mesh *>::iterator i=path_meshes.begin(); i!=path_meshes.end(); ++i)
 139                 delete *i;
 140 }
 141
 142 void TrackType3D::get_bounds(float angle, Point &minp, Point &maxp) const
 143 {
 144         float c = cos(-angle);
 145         float s = sin(-angle);
 146
 147         minp = maxp = Point();
 148         minp.z = min_z;
 149         maxp.z = max_z;
 150
 151         for(vector<Point>::const_iterator i=border.begin(); i!=border.end(); ++i)
 152         {
 153                 float x = c*i->x-s*i->y;
 154                 float y = s*i->x+c*i->y;
 155
 156                 minp.x = min(minp.x, x);
 157                 minp.y = min(minp.y, y);
 158                 maxp.x = max(maxp.x, x);
 159                 maxp.y = max(maxp.y, y);
 160         }
 161 }
 162
 163 const GL::Mesh &TrackType3D::get_path_mesh(unsigned p) const
 164 {
 165         if(p>=path_meshes.size() || !path_meshes[p])
 166                 throw InvalidParameterValue("Invalid path");
 167         return *path_meshes[p];
 168 }
 169
 170 void TrackType3D::build_part(const TrackPart &part, const Profile &profile, const Point &offset, GL::MeshBuilder &bld, unsigned &base_index)
 171 {
 172         float plen = part.get_length();
 173         unsigned nsegs = (part.is_curved() ? static_cast<unsigned>(plen*32)+1 : 1);
 174
 175         unsigned n_points = profile.get_n_points();
 176         for(unsigned i=0; i<=nsegs; ++i)
 177         {
 178                 TrackPoint basep = part.get_point(i*plen/nsegs);
 179                 float c = cos(basep.dir);
 180                 float s = sin(basep.dir);
 181
 182                 Point p;
 183                 for(unsigned j=0; j<n_points; ++j)
 184                 {
 185                         // TODO: smoothing - only duplicate vertex if the angle is large enough
 186
 187                         p = profile.get_point(j);
 188                         p.z = basep.pos.z+p.y+offset.y;
 189                         p.y = basep.pos.y-c*(p.x+offset.x);
 190                         p.x = basep.pos.x+s*(p.x+offset.x);
 191                         if(j>0)
 192                                 bld.vertex(p.x, p.y, p.z);
 193
 194                         if(j+1<n_points)
 195                         {
 196                                 Point n = profile.get_edge_normal(j);
 197                                 bld.normal(s*n.x, -c*n.x, n.y);
 198                                 bld.vertex(p.x, p.y, p.z);
 199                         }
 200
 201                         border.push_back(p);
 202                 }
 203         }
 204
 205         for(unsigned i=0; i+1<n_points; ++i)
 206         {
 207                 bld.begin(GL::TRIANGLE_STRIP);
 208                 for(unsigned j=0; j<=nsegs; ++j)
 209                 {
 210                         unsigned k = (j*(n_points-1)+i)*2;
 211                         bld.element(base_index+k+1);
 212                         bld.element(base_index+k);
 213                 }
 214                 bld.end();
 215         }
 216
 217         base_index += (nsegs+1)*(n_points-1)*2;
 218 }
 219
 220 } // namespace R2C2