eleni.mutantstargoat.com Git - hair/blob - src/hair.cc

   1 #include <gmath/gmath.h>
   2 #include <stdlib.h>
   3 #include <string>
   4
   5 #include "kdtree.h"
   6 #include "hair.h"
   7
   8 struct Triangle {
   9         Vec3 v[3];
  10         Vec3 n[3];
  11 };
  12
  13 Hair::Hair() {}
  14 Hair::~Hair() {}
  15
  16 static Vec3 calc_rand_point(const Triangle &tr, Vec3 *bary)
  17 {
  18         float u = (float)rand() / (float)RAND_MAX;
  19         float v = (float)rand() / (float)RAND_MAX;
  20
  21         if(u + v > 1) {
  22                 u = 1 - u;
  23                 v = 1 - v;
  24         }
  25
  26         float c = 1 - (u + v);
  27
  28         Vec3 rp = u * tr.v[0] + v * tr.v[1] + c * tr.v[3];
  29
  30         bary->x = u;
  31         bary->y = v;
  32         bary->z = c;
  33
  34         return rp;
  35 }
  36
  37 static void get_spawn_triangles(const Mesh *m, float thresh, std::vector<Triangle> *faces)
  38 {
  39         for(size_t i=0; i<m->indices.size() / 3; i++) {
  40                 bool is_spawn = true;
  41                 int idx[3];
  42                 for(int j=0; j<3; j++) {
  43                         idx[j] = i * 3 + j;
  44                         float c = (m->colors[idx[j]].x + m->colors[idx[j]].y + m->colors[idx[j]].z) / 3;
  45                         if (c >= thresh) {
  46                                 is_spawn = false;
  47                                 break;
  48                         }
  49                 }
  50
  51                 if(is_spawn) {
  52                         Triangle t;
  53                         for(int j=0; j<3; j++) {
  54                                 t.v[j] = m->vertices[idx[j]];
  55                                 t.n[j] = m->normals[idx[j]];
  56                         }
  57                         faces->push_back(t);
  58                 }
  59         }
  60 }
  61
  62 bool Hair::init(const Mesh *m, int max_num_spawns, float thresh)
  63 {
  64         std::vector<Triangle> faces;
  65         kdtree *kd = kd_create(3);
  66         const float min_dist = 0.05;
  67
  68         get_spawn_triangles(m, thresh, &faces);
  69
  70         for(int i = 0; i < max_num_spawns; i++) {
  71                 // Poisson
  72                 int rnum = (float)((float)rand() / (float)RAND_MAX) * faces.size();
  73                 Triangle rtriangle = faces[rnum];
  74                 Vec3 bary;
  75                 Vec3 rpoint = calc_rand_point(rtriangle, &bary);
  76
  77                 kdres *res = kd_nearest3f(kd, rpoint.x, rpoint.y, rpoint.z);
  78                 if (!kd_res_end(res)) {
  79                         Vec3 nearest;
  80                         kd_res_item3f(res, &nearest.x, &nearest.y, &nearest.z);
  81                         if(distance_sq(rpoint, nearest) < min_dist * min_dist)
  82                                 continue;
  83                 }
  84
  85                 /* weighted sum of the triangle's vertex normals */
  86                 Vec3 spawn_dir = rtriangle.n[0] * bary.x + rtriangle.n[1] * bary.y + rtriangle.n[2] * bary.z;
  87                 spawn_directions.push_back(normalize(spawn_dir));
  88                 spawn_points.push_back(rpoint);
  89                 kd_insert3f(kd, rpoint.x, rpoint.y, rpoint.z, 0);
  90         }
  91
  92         kd_free(kd);
  93         return true;
  94 }
  95
  96 void Hair::draw() const
  97 {
  98 }