/*libdmtx - Data Matrix Encoding/Decoding LibraryCopyright (C) 2006 Mike LaughtonThis library is free software; you can redistribute it and/ormodify it under the terms of the GNU Lesser General PublicLicense as published by the Free Software Foundation; eitherversion 2.1 of the License, or (at your option) any later version.This library is distributed in the hope that it will be useful,but WITHOUT ANY WARRANTY; without even the implied warranty ofMERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNULesser General Public License for more details.You should have received a copy of the GNU Lesser General PublicLicense along with this library; if not, write to the Free SoftwareFoundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USAContact: mike@dragonflylogic.com*//* $Id: dmtxvector2.c,v 1.5 2006/10/12 18:05:37 mblaughton Exp $ *//** * * */extern DmtxVector2 *dmtxVector2AddTo(DmtxVector2 *v1, DmtxVector2 *v2){   v1->X += v2->X;   v1->Y += v2->Y;   return v1;}/** * * */extern DmtxVector2 *dmtxVector2Add(DmtxVector2 *vOut, DmtxVector2 *v1, DmtxVector2 *v2){   *vOut = *v1;   return dmtxVector2AddTo(vOut, v2);}/** * * */extern DmtxVector2 *dmtxVector2SubFrom(DmtxVector2 *v1, DmtxVector2 *v2){   v1->X -= v2->X;   v1->Y -= v2->Y;   return v1;}/** * * */extern DmtxVector2 *dmtxVector2Sub(DmtxVector2 *vOut, DmtxVector2 *v1, DmtxVector2 *v2){   *vOut = *v1;   return dmtxVector2SubFrom(vOut, v2);}/** * * */extern DmtxVector2 *dmtxVector2ScaleBy(DmtxVector2 *v, float s){   v->X *= s;   v->Y *= s;   return v;}/** * * */extern DmtxVector2 *dmtxVector2Scale(DmtxVector2 *vOut, DmtxVector2 *v, float s){   *vOut = *v;   return dmtxVector2ScaleBy(vOut, s);}/** * * */extern floatdmtxVector2Cross(DmtxVector2 *v1, DmtxVector2 *v2){   return (v1->X * v2->Y) - (v1->Y * v2->X);}/** * * */extern floatdmtxVector2Norm(DmtxVector2 *v){   float mag;   mag = dmtxVector2Mag(v);   assert(mag > DMTX_ALMOST_ZERO);   dmtxVector2ScaleBy(v, 1/mag);   return mag;}/** * * */extern floatdmtxVector2Dot(DmtxVector2 *v1, DmtxVector2 *v2){   return (v1->X * v2->X) + (v1->Y * v2->Y);}/** * * */extern floatdmtxVector2Mag(DmtxVector2 *v){   return sqrt(v->X * v->X + v->Y * v->Y);}/** * * */extern floatdmtxDistanceFromRay2(DmtxRay2 *r, DmtxVector2 *q){   DmtxVector2 vSubTmp;   // Assumes that v is a unit vector   assert(fabs(1.0 - dmtxVector2Mag(&(r->v))) < DMTX_ALMOST_ZERO);   return dmtxVector2Cross(&(r->v), dmtxVector2Sub(&vSubTmp, q, &(r->p)));}/** * * */extern floatdmtxDistanceAlongRay2(DmtxRay2 *r, DmtxVector2 *q){   DmtxVector2 vSubTmp;// Assumes that v is a unit vector#ifdef DEBUG   if(fabs(1.0 - dmtxVector2Mag(v)) > DMTX_ALMOST_ZERO) {      ; // XXX big error goes here   }#endif   return dmtxVector2Dot(dmtxVector2Sub(&vSubTmp, q, &(r->p)), &(r->v));}/** * * */extern intdmtxRay2Intersect(DmtxVector2 *point, DmtxRay2 *p0, DmtxRay2 *p1){   float numer, denom;   DmtxVector2 w;   denom = dmtxVector2Cross(&(p1->v), &(p0->v));   if(fabs(denom) < DMTX_ALMOST_ZERO)      return DMTX_FAILURE;   dmtxVector2Sub(&w, &(p1->p), &(p0->p));   numer = dmtxVector2Cross(&(p1->v), &w);   return dmtxPointAlongRay2(point, p0, numer/denom);}/** * * */extern intdmtxPointAlongRay2(DmtxVector2 *point, DmtxRay2 *r, float t){   DmtxVector2 vTmp;   // Ray should always have unit length of 1   assert(fabs(1.0 - dmtxVector2Mag(&(r->v))) < DMTX_ALMOST_ZERO);   dmtxVector2Scale(&vTmp, &(r->v), t);   dmtxVector2Add(point, &(r->p), &vTmp);   return DMTX_SUCCESS;}