typedef struct {
   GLenum mode;
   GLenum format; // GL_T2F_V3F, GL_V2F
   GLint texname;
   unsigned char r, g, b, a;
} rc_key_t;

typedef struct {
   HV *hv;
} rc_t;

typedef SV rc_array_t;

static rc_t *
rc_alloc ()
{
  rc_t *rc = g_slice_new0 (rc_t);
  rc->hv = newHV ();

  return rc;
}

static void
rc_free (rc_t *rc)
{
  SvREFCNT_dec (rc->hv);
  g_slice_free (rc_t, rc);
}

static void
rc_clear (rc_t *rc)
{
  hv_clear (rc->hv);
}

static rc_array_t *
rc_array (rc_t *rc, rc_key_t *k)
{
  SV *sv = *hv_fetch (rc->hv, (char *)k, sizeof (*k), 1);

  if (SvTYPE (sv) != SVt_PV)
    {
      sv_upgrade (sv, SVt_PV);
      SvPOK_only (sv);
    }

  return sv;
}

static void
rc_v2f (rc_array_t *arr, float x, float y)
{
  STRLEN len = SvCUR (arr) + sizeof (float) * 2;
  SvGROW (arr, len);

  ((float *)SvEND (arr))[0] = x;
  ((float *)SvEND (arr))[1] = y;

  SvCUR_set (arr, len);
}

static void
rc_t2f_v3f (rc_array_t *arr, float u, float v, float x, float y, float z)
{
  STRLEN len = SvCUR (arr) + sizeof (float) * 5;
  SvGROW (arr, len);

  ((float *)SvEND (arr))[0] = u;
  ((float *)SvEND (arr))[1] = v;

  ((float *)SvEND (arr))[2] = x;
  ((float *)SvEND (arr))[3] = y;
  ((float *)SvEND (arr))[4] = z;

  SvCUR_set (arr, len);
}

static void
rc_draw (rc_t *rc)
{
  HE *he;

  hv_iterinit (rc->hv);
  while ((he = hv_iternext (rc->hv)))
    {
      rc_key_t *key = (rc_key_t *)HeKEY (he);
      rc_array_t *arr = HeVAL (he);
      STRLEN len;
      char *arr_pv = SvPV (arr, len);
      GLsizei stride;

      stride = key->format == GL_T2F_V3F ? sizeof (float) * 5
             : key->format == GL_V2F     ? sizeof (float) * 2
             : 65536;

      if (key->texname)
        {
          glBindTexture (GL_TEXTURE_2D, key->texname);
          glEnable (GL_TEXTURE_2D);
        }
      else
        glDisable (GL_TEXTURE_2D);

      glColor4ub (key->r, key->g, key->b, key->a);
      glInterleavedArrays (key->format, 0, (void *)arr_pv);
      glDrawArrays (key->mode, 0, len / stride);
    }

  glDisable (GL_TEXTURE_2D);
}