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

   1 #include <GL/glew.h>
   2
   3 #include <float.h>
   4 #include <gmath/gmath.h>
   5 #include <stdlib.h>
   6 #include <string>
   7
   8 #include "kdtree.h"
   9 #include "hair.h"
  10
  11 struct Triangle {
  12         Vec3 v[3];
  13         Vec3 n[3];
  14 };
  15
  16 Hair::Hair() {}
  17 Hair::~Hair() {}
  18
  19 static Vec3 calc_rand_point(const Triangle &tr, Vec3 *bary)
  20 {
  21         float u = (float)rand() / (float)RAND_MAX;
  22         float v = (float)rand() / (float)RAND_MAX;
  23
  24         if(u + v > 1) {
  25                 u = 1 - u;
  26                 v = 1 - v;
  27         }
  28
  29         float c = 1 - (u + v);
  30
  31         Vec3 rp = u * tr.v[0] + v * tr.v[1] + c * tr.v[2];
  32
  33         bary->x = u;
  34         bary->y = v;
  35         bary->z = c;
  36
  37 //      printf("u %f v %f c %f sum: %f\n", u, v, c, u+v+c);
  38         return rp;
  39 }
  40
  41 static void get_spawn_triangles(const Mesh *m, float thresh, std::vector<Triangle> *faces)
  42 {
  43         if (!m) {
  44                 fprintf(stderr, "Func: %s, invalid mesh.\n", __func__);
  45                 exit(1);
  46         }
  47         float min_y = FLT_MAX;
  48         float max_y = -FLT_MAX;
  49
  50         for(size_t i=0; i<m->indices.size() / 3; i++) {
  51                 bool is_spawn = true;
  52                 int idx[3];
  53                 for(int j=0; j<3; j++) {
  54                         idx[j] = m->indices[i * 3 + j];
  55                         float c = (m->colors[idx[j]].x + m->colors[idx[j]].y + m->colors[idx[j]].z) / 3;
  56                         if (c >= thresh) {
  57                                 is_spawn = false;
  58                                 break;
  59                         }
  60                 }
  61
  62                 if(is_spawn) {
  63                         Triangle t;
  64                         for(int j=0; j<3; j++) {
  65                                 t.v[j] = m->vertices[idx[j]];
  66                                 t.n[j] = m->normals[idx[j]];
  67                                 if(t.v[j].y < min_y)
  68                                         min_y = t.v[j].y;
  69                                 if(t.v[j].y > max_y)
  70                                         max_y = t.v[j].y;
  71                         }
  72                         faces->push_back(t);
  73                 }
  74         }
  75         printf("spawn tri AABB: min y: %f max y: %f\n", min_y, max_y);
  76 }
  77
  78 bool Hair::init(const Mesh *m, int max_num_spawns, float thresh)
  79 {
  80         std::vector<Triangle> faces;
  81         kdtree *kd = kd_create(3);
  82         const float min_dist = 0.05;
  83
  84         if(!m) {
  85                 fprintf(stderr, "Func %s: invalid mesh.\n", __func__);
  86                 return false;
  87         }
  88
  89         get_spawn_triangles(m, thresh, &faces);
  90
  91         for(int i = 0; i < max_num_spawns; i++) {
  92                 // Poisson
  93                 int rnum = (float)((float)rand() / (float)RAND_MAX) * faces.size();
  94                 Triangle rtriangle = faces[rnum];
  95                 Vec3 bary;
  96                 Vec3 rpoint = calc_rand_point(rtriangle, &bary);
  97
  98                 kdres *res = kd_nearest3f(kd, rpoint.x, rpoint.y, rpoint.z);
  99
 100                 if (res && !kd_res_end(res)) {
 101                         Vec3 nearest;
 102                         kd_res_item3f(res, &nearest.x, &nearest.y, &nearest.z);
 103                         if(distance_sq(rpoint, nearest) < min_dist * min_dist)
 104                                 continue;
 105                 }
 106
 107                 /* weighted sum of the triangle's vertex normals */
 108                 Vec3 spawn_dir = rtriangle.n[0] * bary.x + rtriangle.n[1] * bary.y + rtriangle.n[2] * bary.z;
 109                 spawn_directions.push_back(normalize(spawn_dir));
 110                 spawn_points.push_back(rpoint);
 111                 kd_insert3f(kd, rpoint.x, rpoint.y, rpoint.z, 0);
 112         }
 113
 114         kd_free(kd);
 115         return true;
 116 }
 117
 118 void Hair::draw() const
 119 {
 120         glPushAttrib(GL_ENABLE_BIT);
 121         glDisable(GL_DEPTH_TEST);
 122         glDisable(GL_LIGHTING);
 123         glPointSize(2);
 124         glBegin(GL_POINTS);
 125         for(size_t i = 0; i < spawn_points.size(); i++) {
 126                 glColor3f(1, 1, 0);
 127                 glVertex3f(spawn_points[i].x, spawn_points[i].y, spawn_points[i].z);
 128         }
 129         glEnd();
 130         glPopAttrib();
 131 }