text: /*                         T R A N S L A T E _ T G C . C
   * BRL-CAD
   *
   * Copyright (c) 2008-2022 United States Government as represented by
   * the U.S. Army Research Laboratory.
   *
   * This library is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public License
   * version 2.1 as published by the Free Software Foundation.
   *
   * This library is distributed in the hope that it will be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this file; see the file named COPYING for more
   * information.
   */
  /** @file libged/translate_tgc.c
   *
   * The translate_tgc command.
   *
   */
  
  #include "common.h"
  
  #include <string.h>
  
  #include "bu/cmd.h"
  #include "rt/geom.h"
  #include "raytrace.h"
  
  #include "./ged_private.h"
  
  
  int
  _ged_translate_tgc(struct ged *gedp, struct rt_tgc_internal *tgc, const char *attribute, vect_t tvec, int rflag)
  {
      fastf_t la, lb, lc, ld;
      vect_t hvec;
  
      RT_TGC_CK_MAGIC(tgc);
  
      VSCALE(tvec, tvec, gedp->dbip->dbi_local2base);
  
      switch (attribute[0]) {
  	case 'h':
  	case 'H':
  	    switch (attribute[1]) {
  		case '\0':
  		    if (rflag) {
  			VADD2(hvec, tgc->h, tvec);
  		    } else {
  			VSUB2(hvec, tvec, tgc->v);
  		    }
  
  		    /* check for zero H vector */
  		    if (MAGNITUDE(hvec) <= SQRT_SMALL_FASTF) {
  			bu_vls_printf(gedp->ged_result_str, "Zero H vector not allowed.");
  			return BRLCAD_ERROR;
  		    }
  
  		    VMOVE(tgc->h, hvec);
  
  		    break;
  		case 'r':
  		case 'R':
  		    if (attribute[2] != '\0') {
  			bu_vls_printf(gedp->ged_result_str, "bad tgc attribute - %s", attribute);
  			return BRLCAD_ERROR;
  		    }
  
  		    if (rflag) {
  			VADD2(hvec, tgc->h, tvec);
  		    } else {
  			VSUB2(hvec, tvec, tgc->v);
  		    }
  
  		    /* check for zero H vector */
  		    if (MAGNITUDE(hvec) <= SQRT_SMALL_FASTF) {
  			bu_vls_printf(gedp->ged_result_str, "Zero H vector not allowed.");
  			return BRLCAD_ERROR;
  		    }
  
  		    VMOVE(tgc->h, hvec);
  
  		    /* have new height vector -- redefine rest of tgc */
  		    la = MAGNITUDE(tgc->a);
  		    lb = MAGNITUDE(tgc->b);
  		    lc = MAGNITUDE(tgc->c);
  		    ld = MAGNITUDE(tgc->d);
  
  		    /* find 2 perpendicular vectors normal to H for new A, B */
  		    VCROSS(tgc->b, tgc->h, tgc->a);
  		    VCROSS(tgc->a, tgc->b, tgc->h);
  
  		    VUNITIZE(tgc->a);
  		    VUNITIZE(tgc->b);
  
  		    /* Create new C, D from unit length A, B, with previous len */
  		    VSCALE(tgc->c, tgc->a, lc);
  		    VSCALE(tgc->d, tgc->b, ld);
  
  		    /* Restore original vector lengths to A, B */
  		    VSCALE(tgc->a, tgc->a, la);
  		    VSCALE(tgc->b, tgc->b, lb);
  
  		    break;
  		default:
  		    bu_vls_printf(gedp->ged_result_str, "bad tgc attribute - %s", attribute);
  		    return BRLCAD_ERROR;
  	    }
  
  	    break;
  	default:
  	    bu_vls_printf(gedp->ged_result_str, "bad tgc attribute - %s", attribute);
  	    return BRLCAD_ERROR;
      }
  
      return BRLCAD_OK;
  }
  
  
  /*
   * Local Variables:
   * tab-width: 8
   * mode: C
   * indent-tabs-mode: t
   * c-file-style: "stroustrup"
   * End:
   * ex: shiftwidth=4 tabstop=8
   */
  