-+-+-+-+-+-+-+-+ START OF PART 266 -+-+-+-+-+-+-+-+
X  ** of orthogonal axes denoted by uaxis, vaxis, naxis`20
X  */
X  naxis = ptk_unitv3(viewplanenormal);
X  uaxis = ptk_unitv3(&vuvxvpn);
X  vaxis = ptk_crossv3(&naxis, &uaxis);
X  vaxis = ptk_unitv3(&vaxis);
X  /* form view orientation matrix */
X  ptk_unitmatrix3(temp);
X  temp`5B0`5D`5B0`5D = uaxis.x;
X  temp`5B0`5D`5B1`5D = uaxis.y;
X  temp`5B0`5D`5B2`5D = uaxis.z;
X  temp`5B0`5D`5B3`5D = -(uaxis.x * viewrefpoint->x + uaxis.y *`20
X                   viewrefpoint->y + uaxis.z * viewrefpoint->z);
X  temp`5B1`5D`5B0`5D = vaxis.x;
X  temp`5B1`5D`5B1`5D = vaxis.y;
X  temp`5B1`5D`5B2`5D = vaxis.z;
X  temp`5B1`5D`5B3`5D = -(vaxis.x * viewrefpoint->x + vaxis.y *`20
X                   viewrefpoint->y + vaxis.z * viewrefpoint->z);
X  temp`5B2`5D`5B0`5D = naxis.x;
X  temp`5B2`5D`5B1`5D = naxis.y;
X  temp`5B2`5D`5B2`5D = naxis.z;
X  temp`5B2`5D`5B3`5D = -(naxis.x * viewrefpoint->x + naxis.y *`20
X                   viewrefpoint->y + naxis.z * viewrefpoint->z);
X  ptk_concatenatematrix3(operation, temp, matrix, matrix);
X`7D  /* ptk_evalvieworientation3 */
X
X/*--------------------------------------------------------------------------
V*/
X
X/*function:external*/
Xextern void ptk_evalvieworientation(C(Ppoint *) viewrefpoint,`20
X`09`09`09`09    C(Ppoint *) viewupvector,`20
X                                    C(Pcomptype) operation,`20
X                                    C(Pmatrix) matrix, C(Pint *)error)
XPreANSI(Ppoint *viewrefpoint)
XPreANSI(Ppoint *viewupvector)
XPreANSI(Pcomptype operation)`20
XPreANSI(Pmatrix matrix)
XPreANSI(Pint *error)
X/*
X** \parambegin
X** \param`7BPpoint *`7D`7Bviewrefpoint`7D`7Bview reference point`7D`7BIN`7D
X** \param`7BPpoint *`7D`7Bviewupvector`7D`7Bview up vector`7D`7BIN`7D
X** \param`7BPcomptype`7D`7Boperation`7D`7Bconcatenation operation`7D`7BIN`7D
X** \param`7BPmatrix`7D`7Bmatrix`7D`7B3x3 matrix`7D`7BOUT`7D
X** \param`7BPint *`7D`7Berror`7D`7Berror code`7D`7BOUT`7D
X** \paramend
X** \blurb`7BThis function computes`20
X** a 2D PHIGS view orientation matrix on the basis of
X** a specified view reference point (\pardesc`7Bviewrefpoint`7D)
X** and a view up vector
X** (\pardesc`7Bviewupvector`7D).  If the function succeeds,
X** \pardesc`7Berror`7D is set to \pardesc`7Bptkcpcok`7D. Otherwise,`20
X** \pardesc`7Berror`7D is 63 if the view up vector is null.`7D
X*/
X`7B
X  Ppoint3 uaxis, vaxis, naxis, vuvxvpn;
X  Pmatrix temp;
X
X  *error = ptkcpcok;
X  if (ptk_nullv(viewupvector))`20
X  `7B
X    *error = 63;
X  `7D`20
X  if (*error != ptkcpcok)`20
X  `7B
X    return;
X  `7D  /* if error = 0 */
X  /* generate from viewplanenormal and viewupvector a set
X  ** of orthogonal axes denoted by uaxis, vaxis, naxis`20
X  */
X  naxis = ptk_point3(0.0, 0.0, 1.0);
X  vaxis = ptk_point3(viewupvector->x, viewupvector->y, 0.0);
X  vaxis = ptk_unitv3(&vaxis);
X/*  uaxis = ptk_crossv3(naxis, vaxis); */
X  uaxis = ptk_unitv3(&uaxis);
X  /* form view orientation matrix */
X  ptk_unitmatrix(temp);
X  temp`5B0`5D`5B0`5D = uaxis.x;
X  temp`5B0`5D`5B1`5D = uaxis.y;
X  temp`5B0`5D`5B2`5D = uaxis.z;
X/*  temp`5B0`5D`5B3`5D = -(uaxis.x * viewrefpoint->x + uaxis.y * viewrefpoin
Vt->y); */
X  temp`5B1`5D`5B0`5D = vaxis.x;
X  temp`5B1`5D`5B1`5D = vaxis.y;
X  temp`5B1`5D`5B2`5D = 0.0;
X/*  temp`5B1`5D`5B3`5D = -(vaxis.x * viewrefpoint->x + vaxis.y * viewrefpoin
Vt->y); */
X  temp`5B2`5D`5B0`5D = naxis.x;
X  temp`5B2`5D`5B1`5D = naxis.y;
X  temp`5B2`5D`5B2`5D = naxis.z;
X  ptk_concatenatematrix(operation, temp, matrix, matrix);
X`7D  /* ptk_evalvieworientation */
X
X/*--------------------------------------------------------------------------
V*/
X
X/*function:external*/
Xextern void ptk_evalviewmapping3(C(Plimit3 *) wlimits, C(Plimit3 *) vlimits,
V`20
X                                C(Pprojtype) viewtype,`20
X                                C(Ppoint3 *) refpoint, C(Pfloat) vplanedist,
V`20
X                                C(Pcomptype) operation, C(Pmatrix3) matrix,`
V20
X                                C(Pint *)error)
XPreANSI(Plimit3 *wlimits)
XPreANSI(Plimit3 *vlimits)`20
XPreANSI(Pprojtype viewtype)`20
XPreANSI(Ppoint3 *refpoint)
XPreANSI(Pfloat vplanedist)`20
XPreANSI(Pcomptype operation)
XPreANSI(Pmatrix3 matrix)`20
XPreANSI(Pint *error)
X/*
X** \parambegin
X** \param`7BPlimit3 *`7D`7Bwlimits`7D`7Bwindow limits`7D`7BIN`7D
X** \param`7BPlimit3 *`7D`7Bvlimits`7D`7Bviewport limits`7D`7BIN`7D
X** \param`7BPprojtype`7D`7Bviewtype`7D`7Bprojection type`7D`7BIN`7D
X** \param`7BPpoint3 *`7D`7Brefpoint`7D`7Bprojection reference point`7D`7BIN`
V7D
X** \param`7BPfloat`7D`7Bvplanedist`7D`7Bview plane distance`7D`7BIN`7D
X** \param`7BPcomptype`7D`7Boperation`7D`7Bconcatenation operation`7D`7BIN`7D
X** \param`7BPmatrix3`7D`7Bmatrix`7D`7B4x4 matrix`7D`7BOUT`7D
X** \param`7BPint *`7D`7Berror`7D`7Berror code`7D`7BOUT`7D
X** \paramend
X** \blurb`7BThis function evaluates a 3D PHIGS view mapping matrix.
X** If the function succeeds,
X** \pardesc`7Berror`7D is set to \pardesc`7Bptkcpcok`7D. Otherwise,`20
X** \pardesc`7Berror`7D is`20
X** 329 if the window limits are not valid,
X** 336 if the back plane is in front of front plane,
X** 330 if the viewport limits are not valid,
X** 335 if the projection reference point is on the view plane,
X** and 340 if the projection reference point is between front and back plane
Vs.`7D
X*/
X`7B
X  Ppoint3 projectordirn, viewwindowcentre, vref;
X  Pmatrix3 temp;
X  Plimit3 templim;
X  Pint err;
X
X  templim = *wlimits;
X  *error = ptkcpcok;
X  /* check for valid window limits */
X  if (templim.xmin >= templim.xmax `7C`7C
X      templim.ymin >= templim.ymax)`20
X  `7B
X    *error = 329;
X    return;
X  `7D
X  /* check that back plane is not in front of front plane */
X  if (templim.zmin >= templim.zmax)`20
X  `7B
X    *error = 336;
X    return;
X  `7D
X  /* check for valid viewport limits */
X  if (!validbounds3(vlimits))`20
X  `7B
X    *error = 330;
X    return;
X  `7D
X  /* check that PRP not positioned on the view plane */
X  if (ptk_equal(refpoint->z, vplanedist))`20
X  `7B
X    *error = 335;
X    return;
X  `7D
X  /* check that PRP not between the front and back planes */
X  if (refpoint->z < templim.zmax && refpoint->z > templim.zmin)`20
X  `7B
X    *error = 340;
X    return;
X  `7D
X  /* if everything is OK error is set to zero and a value computed for`20
X  ** matrix.
X  */
X  *error = ptkcpcok;
X  ptk_unitmatrix3(temp);
X  switch (viewtype)`20
X  `7B
X  case PPERSPECTIVE:
X    temp`5B0`5D`5B0`5D = refpoint->z - vplanedist;
X    temp`5B0`5D`5B2`5D = -refpoint->x;
X    temp`5B0`5D`5B3`5D = refpoint->x * vplanedist;
X    temp`5B1`5D`5B0`5D = 0.0;
X    temp`5B1`5D`5B1`5D = refpoint->z - vplanedist;
X    temp`5B1`5D`5B2`5D = -refpoint->y;
X    temp`5B1`5D`5B3`5D = refpoint->y * vplanedist;
X    temp`5B2`5D`5B2`5D = 0.0;
X    temp`5B2`5D`5B3`5D = 1.0;
X    temp`5B3`5D`5B2`5D = -1.0;
X    temp`5B3`5D`5B3`5D = refpoint->z;
X    break;
X
X  case PPARALLEL:
X    viewwindowcentre.x = (templim.xmin + templim.xmax) / 2;
X    viewwindowcentre.y = (templim.ymin + templim.ymax) / 2;
X    viewwindowcentre.z = vplanedist;
X    projectordirn = ptk_subv3(refpoint, &viewwindowcentre);
X    projectordirn = ptk_scalev3(&projectordirn,`20
X                               1.0 / (refpoint->z - vplanedist));
X    temp`5B0`5D`5B2`5D = -projectordirn.x;
X    temp`5B0`5D`5B3`5D = vplanedist * projectordirn.x;
X    temp`5B1`5D`5B2`5D = -projectordirn.y;
X    temp`5B1`5D`5B3`5D = vplanedist * projectordirn.y;
X    break;
X  `7D
X  /* The z coordinate is unchanged by the transformation matrix above for
X  ** parallel projection types and changed for perspective projection
X  ** types. Different action is therefore required in each case so that
X  ** points at the front and back planes are always mapped onto points at
X  ** the front and back of the projection viewport`20
X  */
X  if (viewtype == PPERSPECTIVE)`20
X  `7B
X    templim.zmin = 1.0 / (refpoint->z - templim.zmin);
X    templim.zmax = 1.0 / (refpoint->z - templim.zmax);
X  `7D
X  ptk_box3tobox3(&templim, vlimits, FALSE, PPOSTCONCATENATE, temp, &err);
X  ptk_concatenatematrix3(operation, temp, matrix, matrix);
X`7D  /* ptk_evalviewmapping3 */
X
X/*--------------------------------------------------------------------------
V*/
X
X/*function:external*/
Xextern void ptk_evalviewmapping(C(Plimit *) wlimits, C(Plimit *) vlimits,`20
X                                C(Pcomptype) operation, C(Pmatrix) matrix,`2
V0
X                                C(Pint *)error)
XPreANSI(Plimit *wlimits)
XPreANSI(Plimit *vlimits)`20
XPreANSI(Pcomptype operation)
XPreANSI(Pmatrix matrix)`20
XPreANSI(Pint *error)
X/*
X** \parambegin
X** \param`7BPlimit *`7D`7Bwlimits`7D`7Bwindow limits`7D`7BIN`7D
X** \param`7BPlimit *`7D`7Bvlimits`7D`7Bviewport limits`7D`7BIN`7D
X** \param`7BPcomptype`7D`7Boperation`7D`7Bconcatenation operation`7D`7BIN`7D
X** \param`7BPmatrix`7D`7Bmatrix`7D`7B3x3 matrix`7D`7BOUT`7D
X** \param`7BPint *`7D`7Berror`7D`7Berror code`7D`7BOUT`7D
X** \paramend
X** \blurb`7BThis function evaluates a 2d PHIGS view mapping matrix.
X** If the function succeeds,
X** \pardesc`7Berror`7D is set to \pardesc`7Bptkcpcok`7D. Otherwise,`20
X** \pardesc`7Berror`7D is
X** 329 if the window limits are not valid,
X** and 330 if the viewport limits are not valid.`7D
X*/
X`7B
X  Pmatrix temp;
X  Pint err;
X
X  *error = ptkcpcok;
X  /* check for valid window limits */
X  if (wlimits->xmin >= wlimits->xmax `7C`7C
X      wlimits->ymin >= wlimits->ymax)`20
X  `7B
X    *error = 329;
X    return;
X  `7D
X  /* check for valid viewport limits */
X  if (!validbounds(vlimits))`20
X  `7B
X    *error = 330;
X    return;
X  `7D
X  /* if everything is OK error is set to zero and a value computed for`20
X  ** matrix.
X  */
X  *error = ptkcpcok;
X  ptk_unitmatrix(temp);
X  ptk_boxtobox(wlimits, vlimits, FALSE, PPOSTCONCATENATE, temp, &err);
X  ptk_concatenatematrix(operation, temp, matrix, matrix);
X`7D  /* ptk_evalviewmapping */
X
X/*--------------------------------------------------------------------------
V*/
X
X/*function:external*/
Xextern void ptk_stackmatrix3(C(Pmatrix3) matrix)
XPreANSI(Pmatrix3 matrix)
X/*
X** \parambegin
X** \param`7BPmatrix3`7D`7Bmatrix`7D`7B4x4 matrix`7D`7BIN`7D
X** \paramend
X** \blurb`7BThis function pushes
X** the $4 \times 4$ matrix \pardesc`7Bmatrix`7D onto the transformation stac
Vk.`7D
X*/
X`7B
X  newone3 = (ptksstack3 *)malloc(sizeof(ptksstack3));
X  newone3->ptkpnext = listhead3;
X  memcpy(newone3->ptkamat, matrix, sizeof(Pmatrix3));
X  listhead3 = newone3;
X`7D  /* ptk_stackmatrix3 */
X
X/*--------------------------------------------------------------------------
V*/
X
X/*function:external*/
Xextern void ptk_stackmatrix(C(Pmatrix) matrix)
XPreANSI(Pmatrix matrix)
X/*
X** \parambegin
X** \param`7BPmatrix`7D`7Bmatrix`7D`7B3x3 matrix`7D`7BIN`7D
X** \paramend
X** \blurb`7BThis function pushes the $3 \times 3$ matrix \pardesc`7Bmatrix`7
VD
X**  onto the transformation stack.`7D
X*/
X`7B
X  newone = (ptksstack *)malloc(sizeof(ptksstack));
X  newone->ptkpnext = listhead;
X  memcpy(newone->ptkamat, matrix, sizeof(Pmatrix));
X  listhead = newone;
X`7D  /* ptk_stackmatrix */
X
X/*--------------------------------------------------------------------------
V*/
X
X/*function:external*/
Xextern void ptk_unstackmatrix3(C(Pmatrix3) matrix)
XPreANSI(Pmatrix3 matrix)
X/*
X** \parambegin
X** \param`7BPmatrix3`7D`7Bmatrix`7D`7B4x4 matrix`7D`7BOUT`7D
X** \paramend
X** \blurb`7BThis function
X** pops a $4 \times 4$  matrix`20
X** from the transformation stack and returns it in
X** \pardesc`7Bmatrix`7D.`7D
X*/
X`7B
X  if (listhead3 == NULL)
X    return;
X  memcpy(matrix, listhead3->ptkamat, sizeof(Pmatrix3));
X  newone3 = listhead3->ptkpnext;
X  free(listhead3);
X  listhead3 = newone3;
X`7D  /* ptk_unstackmatrix3 */
X
X/*--------------------------------------------------------------------------
V*/
X
X/*function:external*/
Xextern void ptk_unstackmatrix(C(Pmatrix) matrix)
XPreANSI(Pmatrix matrix)
X/*
X** \parambegin
X** \param`7BPmatrix`7D`7Bmatrix`7D`7B3x3 matrix`7D`7BOUT`7D
X** \paramend
X** \blurb`7BThis function pops a $3 \times 3$ matrix
X** from the transformation stack and returns it in
X** \pardesc`7Bmatrix`7D.`7D
X*/
X`7B
X  if (listhead == NULL)
X    return;
X  memcpy(matrix, listhead->ptkamat, sizeof(Pmatrix));
X  newone = listhead->ptkpnext;
X  free(listhead);
X  listhead = newone;
X`7D  /* ptk_unstackmatrix */
X
X/*--------------------------------------------------------------------------
V*/
X
X/*function:external*/
Xextern void ptk_examinestackmatrix3(C(Pmatrix3) matrix)
XPreANSI(Pmatrix3 matrix)
X/*
X** \parambegin
X** \param`7BPmatrix3`7D`7Bmatrix`7D`7B4x4 matrix`7D`7BIN`7D
X** \paramend
X** \blurb`7BThis function returns the top entry on the transformation stack.
X** The stack is not disturbed.`7D
X*/
X`7B
X  if (listhead3 != NULL)
X    memcpy(matrix, listhead3->ptkamat, sizeof(Pmatrix3));
X`7D  /* ptk_examinestackmatrix3 */
X
X/*--------------------------------------------------------------------------
V*/
X
X/*function:external*/
Xextern void ptk_examinestackmatrix(C(Pmatrix) matrix)
XPreANSI(Pmatrix matrix)
X/*
X** \parambegin
X** \param`7BPmatrix`7D`7Bmatrix`7D`7B3x3 matrix`7D`7BIN`7D
X** \paramend
X** \blurb`7BThis function  returns the top entry on the transformation stack
V.
X** The stack is not disturbed.`7D
X*/
X`7B
X  if (listhead != NULL)
X    memcpy(matrix, listhead->ptkamat, sizeof(Pmatrix));
X`7D  /* ptk_examinestackmatrix */
X
X/*--------------------------------------------------------------------------
V*/
X
X/*function:external*/
Xextern void ptk_3ptto3pt(C(Ppoint3 *) p1, C(Ppoint3 *) p2, C(Ppoint3 *) p3,`
V20
X                         C(Ppoint3 *) q1, C(Ppoint3 *) q2, C(Ppoint3 *) q3,`
V20
X                         C(Pcomptype) operation, C(Pmatrix3) matrix,`20
X                         C(Pint *)error)
XPreANSI(Ppoint3 *p1)
XPreANSI(Ppoint3 *p2)
XPreANSI(Ppoint3 *p3)
XPreANSI(Ppoint3 *q1)`20
XPreANSI(Ppoint3 *q2)
XPreANSI(Ppoint3 *q3)
XPreANSI(Pcomptype operation)`20
XPreANSI(Pmatrix3 matrix)
XPreANSI(Pint *error)
X/*
X** \parambegin
X** \param`7BPpoint3 *`7D`7Bp1`7D`7B3D point`7D`7BIN`7D
X** \param`7BPpoint3 *`7D`7Bp2`7D`7B3D point`7D`7BIN`7D
X** \param`7BPpoint3 *`7D`7Bp3`7D`7B3D point`7D`7BIN`7D
X** \param`7BPpoint3 *`7D`7Bq1`7D`7B3D point`7D`7BIN`7D
X** \param`7BPpoint3 *`7D`7Bq2`7D`7B3D point`7D`7BIN`7D
+-+-+-+-+-+-+-+-  END  OF PART 266 +-+-+-+-+-+-+-+-