#include <stdio.h>
#include <string.h>
#include <GL/gl.h>
#include "libs.h"
#include "objimport.h"

ObjMesh* import_obj_mesh(const char *filename) {
  char buf[1024];
  FILE* f = fopen(filename, "r");
  if(!f) {
    fprintf(stderr, "Failed to load mesh %s\n", filename);
    return 0;
  }

  ObjMesh* m = new ObjMesh;
  float vsum[3];
  memset(vsum, 0, sizeof(float)*3);

  while(fgets(buf, sizeof(buf), f)) {
    if(buf[0] == '#') continue;
    ObjVertex v;
    if(sscanf(buf, "v %f %f %f", &v.p.x, &v.p.y, &v.p.z) == 3) {
      m->vertices.push_back(v);
      vsum[0] += v.p.x;
      vsum[1] += v.p.y;
      vsum[2] += v.p.z;
      continue;
    }
    ObjTriangle t;
    if(sscanf(buf, "f %d/%*d/ %d/%*d/ %d/%*d/", &t.v[0], &t.v[1], &t.v[2]) == 3) {
      t.v[0]--;
      t.v[1]--;
      t.v[2]--;
      m->triangles.push_back(t);
      continue;
    }
  }
  vsum[0] /= m->vertices.size();
  vsum[1] /= m->vertices.size();
  vsum[2] /= m->vertices.size();

  /* Locate the model roughly at 0,0,0. */
  for(unsigned int i = 0; i < m->vertices.size(); i++) {
    m->vertices[i].p.x -= vsum[0];
    m->vertices[i].p.y -= vsum[1];
    m->vertices[i].p.z -= vsum[2];
  }

  printf("%zd vertices\n", m->vertices.size());
  printf("%zd triangles\n", m->triangles.size());
  return m;
}

/* Why not make a display list.. */
void ObjMesh::Render(void) {
  glBegin(GL_TRIANGLES);
  for(unsigned int i = 0; i < triangles.size(); i++) {
    ObjTriangle& t = triangles[i];

    vector3f p0 = vertices[t.v[0]].p;
    vector3f p1 = vertices[t.v[1]].p;
    vector3f p2 = vertices[t.v[2]].p;

    vector3f n = -vector3f::Normalize(vector3f::Cross(p0-p2, p0-p1));

    glNormal3fv(&n[0]);
    glVertex3fv(&vertices[t.v[0]].p[0]);
    glVertex3fv(&vertices[t.v[1]].p[0]);
    glVertex3fv(&vertices[t.v[2]].p[0]);
  }
  glEnd();
}