/* See {tosl_mesh_obj_write.h} */
/* Last edited on 2024-10-07 16:53:07 by stolfi */

#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <assert.h>
#include <time.h>

#include <haf.h>

#include <tosl.h>
#include <tosl_mesh_obj_write.h>

void tosl_mesh_obj_write(FILE *wr, tosl_mesh_t *mesh)
  {
    /* Find coordinate ranges: */
    tosl_point_t vmin, vmax;
    tosl_mesh_coord_range_get(mesh, &vmin, &vmax);
    
    fprintf(wr, "# Created by %s\n", __FUNCTION__);
    fprintf(wr, "\n# VERTICES\n\n");
    for (tosl_vert_id_t iv = 0; iv < mesh->NV; iv++)
      { if ((mesh->Vlab != NULL) && (mesh->Vlab[iv] != NULL)) { fprintf(wr, "# %s :\n", mesh->Vlab[iv]); }
        tosl_point_t *v = &(mesh->Vpos[iv]);
        fprintf(wr, "v");
        for (uint32_t j = 0;  j < 3; j++) 
          { double cj = 2*((double)v->c[j] - vmin.c[j])/((double)vmax.c[j] - vmin.c[j] + 1) - 1.0;
            fprintf(wr, " %8.6f", cj);
          }
        fprintf(wr, "\n");
      }
    fprintf(wr, "\n");
    
    fprintf(wr, "\n# FACE NORMALS\n\n");
    int32_t NA = 2*mesh->NE;
    uint8_t *seen = malloc(NA*sizeof(uint8_t));
    for (tosl_arc_id_t ia = 0; ia < NA; ia++) { seen[ia] = 0; }
    int32_t kf = 0; /* Faces seen so far. */
    for (tosl_arc_id_t ia = 0; ia < NA; ia++)
      { if (seen[ia] == 0)
          { fprintf(wr, "# normal of face %d :\n", kf+1);
            double area, nrm[3], ctr[3];
            tosl_mesh_face_normal_area_center(ia, mesh, &area, nrm, ctr);
            /* Define face normal: */
            fprintf(wr, "vn");
            for (uint32_t j = 0;  j < 3; j++) { fprintf(wr, " %8.6f", nrm[j]); }
            fprintf(wr, "\n");
            /* Mark rest of face as seen: */
            tosl_arc_id_t ka = ia;
            do 
              { assert(seen[ka] == 0); 
                seen[ka] = 1; 
                ka = mesh->Arc[ka].skip;
                assert(ka != -1);
              } 
            while (ka != ia);
            kf++;
          }
      }
    int32_t NF = kf;
   
    fprintf(wr, "\n# FACES\n\n");
    /* Must generate them in the same order as the normals were calculated! */
    for (tosl_arc_id_t ia = 0; ia < NA; ia++) { seen[ia] = 0; }
    kf = 0;
    for (tosl_arc_id_t ia = 0; ia < NA; ia++)
      { if (seen[ia] == 0)
          { fprintf(wr, "# face %d :\n", kf+1);
            fprintf(wr, "f");
            tosl_arc_id_t ka = ia;
            do 
              { assert(seen[ka] == 0); 
                seen[ka] = 1; 
                tosl_vert_id_t kv = mesh->Arc[ka].ivorg;
                fprintf(wr, " %d//%d", kv+1, kf+1);
                ka = mesh->Arc[ka].skip;
                assert(ka != -1);
              } while (ka != ia);
            fprintf(wr, "\n");
            kf++;
          }
      }
    assert(kf == NF);
    fflush(wr);
    free(seen);
  }