1 /*****************************************************************************
5 ** Purpose: Classes for CT scanner
6 ** Programmer: Kevin Rosenberg
9 ** This is part of the CTSim program
10 ** Copyright (c) 1983-2001 Kevin Rosenberg
12 ** $Id: scanner.cpp,v 1.33 2001/03/01 07:30:49 kevin Exp $
14 ** This program is free software; you can redistribute it and/or modify
15 ** it under the terms of the GNU General Public License (version 2) as
16 ** published by the Free Software Foundation.
18 ** This program is distributed in the hope that it will be useful,
19 ** but WITHOUT ANY WARRANTY; without even the implied warranty of
20 ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
21 ** GNU General Public License for more details.
23 ** You should have received a copy of the GNU General Public License
24 ** along with this program; if not, write to the Free Software
25 ** Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
26 ******************************************************************************/
31 const int Scanner::GEOMETRY_INVALID = -1;
32 const int Scanner::GEOMETRY_PARALLEL = 0;
33 const int Scanner::GEOMETRY_EQUIANGULAR = 1;
34 const int Scanner::GEOMETRY_EQUILINEAR = 2;
36 const char* Scanner::s_aszGeometryName[] =
43 const char* Scanner::s_aszGeometryTitle[] =
50 const int Scanner::s_iGeometryCount = sizeof(s_aszGeometryName) / sizeof(const char*);
54 // DetectorArray Construct a DetectorArray
56 DetectorArray::DetectorArray (const int nDet)
59 m_detValues = new DetectorValue [m_nDet];
64 // ~DetectorArray Free memory allocated to a detector array
66 DetectorArray::~DetectorArray (void)
68 delete [] m_detValues;
74 * Scanner::Scanner Construct a user specified detector structure
77 * Scanner (phm, nDet, nView, nSample)
78 * Phantom& phm PHANTOM that we are making detector for
79 * int geomety Geometry of detector
80 * int nDet Number of detector along detector array
81 * int nView Number of rotated views
82 * int nSample Number of rays per detector
85 Scanner::Scanner (const Phantom& phm, const char* const geometryName,
86 int nDet, int nView, int nSample, const double rot_anglen,
87 const double dFocalLengthRatio, const double dCenterDetectorRatio,
88 const double dViewRatio, const double dScanRatio)
91 m_idGeometry = convertGeometryNameToID (geometryName);
92 if (m_idGeometry == GEOMETRY_INVALID) {
94 m_failMessage = "Invalid geometry name ";
95 m_failMessage += geometryName;
99 if (nView < 1 || nDet < 1) {
101 m_failMessage = "nView & nDet must be greater than 0";
110 m_dFocalLengthRatio = dFocalLengthRatio;
111 m_dCenterDetectorRatio = dCenterDetectorRatio;
112 m_dViewRatio = dViewRatio;
113 m_dScanRatio = dScanRatio;
115 m_dViewDiameter = phm.getDiameterBoundaryCircle() * m_dViewRatio;
116 m_dFocalLength = (m_dViewDiameter / 2) * m_dFocalLengthRatio;
117 m_dCenterDetectorLength = (m_dViewDiameter / 2) * m_dCenterDetectorRatio;
118 m_dSourceDetectorLength = m_dFocalLength + m_dCenterDetectorLength;
119 m_dScanDiameter = m_dViewDiameter * m_dScanRatio;
121 m_dXCenter = phm.xmin() + (phm.xmax() - phm.xmin()) / 2;
122 m_dYCenter = phm.ymin() + (phm.ymax() - phm.ymin()) / 2;
123 m_rotLen = rot_anglen;
124 m_rotInc = m_rotLen / m_nView;
125 if (m_idGeometry == GEOMETRY_PARALLEL) {
127 m_detLen = m_dScanDiameter;
128 m_detInc = m_detLen / m_nDet;
129 double dDetectorArrayEndOffset = 0;
130 // For even number of detectors, make detInc slightly larger so that center lies
131 // at nDet/2. Also, extend detector array by one detInc so that all of the phantom is scanned
132 if (m_nDet % 2 == 0) { // Adjust for Even number of detectors
133 m_detInc = m_detLen / (m_nDet - 1); // center detector = (nDet/2)
134 dDetectorArrayEndOffset = m_detInc;
137 double dHalfDetLen = m_detLen / 2;
138 m_initPos.xs1 = m_dXCenter - dHalfDetLen;
139 m_initPos.ys1 = m_dYCenter + m_dFocalLength;
140 m_initPos.xs2 = m_dXCenter + dHalfDetLen + dDetectorArrayEndOffset;
141 m_initPos.ys2 = m_dYCenter + m_dFocalLength;
142 m_initPos.xd1 = m_dXCenter - dHalfDetLen;
143 m_initPos.yd1 = m_dYCenter - m_dCenterDetectorLength;
144 m_initPos.xd2 = m_dXCenter + dHalfDetLen + dDetectorArrayEndOffset;
145 m_initPos.yd2 = m_dYCenter - m_dCenterDetectorLength;
146 m_initPos.angle = 0.0;
147 } else if (m_idGeometry == GEOMETRY_EQUILINEAR) {
148 if (m_dScanDiameter / 2 >= m_dFocalLength) {
150 m_failMessage = "Invalid geometry: Focal length must be larger than scan length";
154 const double dAngle = asin ((m_dScanDiameter / 2) / m_dFocalLength);
155 const double dHalfDetLen = m_dSourceDetectorLength * tan (dAngle);
157 m_detLen = dHalfDetLen * 2;
158 m_detInc = m_detLen / m_nDet;
159 double dDetectorArrayEndOffset = 0;
160 if (m_nDet % 2 == 0) { // Adjust for Even number of detectors
161 m_detInc = m_detLen / (m_nDet - 1); // center detector = (nDet/2)
162 dDetectorArrayEndOffset = m_detInc;
165 m_dFanBeamAngle = dAngle * 2;
166 m_initPos.angle = 0.0;
167 m_initPos.xs1 = m_dXCenter;
168 m_initPos.ys1 = m_dYCenter + m_dFocalLength;
169 m_initPos.xs2 = m_dXCenter;
170 m_initPos.ys2 = m_dYCenter + m_dFocalLength;
171 m_initPos.xd1 = m_dXCenter - dHalfDetLen;
172 m_initPos.yd1 = m_dYCenter - m_dCenterDetectorLength;
173 m_initPos.xd2 = m_dXCenter + dHalfDetLen + dDetectorArrayEndOffset;
174 m_initPos.yd2 = m_dYCenter - m_dCenterDetectorLength;
175 m_initPos.angle = 0.0;
176 } else if (m_idGeometry == GEOMETRY_EQUIANGULAR) {
177 if (m_dScanDiameter / 2 > m_dFocalLength) {
179 m_failMessage = "Invalid geometry: Focal length must be larger than scan length";
182 const double dAngle = asin ((m_dScanDiameter / 2) / m_dFocalLength);
184 m_detLen = 2 * dAngle;
185 m_detInc = m_detLen / m_nDet;
186 double dDetectorArrayEndOffset = 0;
187 if (m_nDet % 2 == 0) { // Adjust for Even number of detectors
188 m_detInc = m_detLen / (m_nDet - 1); // center detector = (nDet/2)
189 dDetectorArrayEndOffset = m_detInc;
191 double dA1 = acos ((m_dScanDiameter / 2) / m_dCenterDetectorLength);
192 double dAngularScale = 2 * (HALFPI + dAngle - dA1) / m_detLen;
193 m_dAngularDetLen = dAngularScale * (m_detLen + dDetectorArrayEndOffset);
194 m_dAngularDetIncrement = dAngularScale * m_detInc;
195 m_initPos.dAngularDet = -m_dAngularDetLen / 2;
197 m_dFanBeamAngle = dAngle * 2;
199 m_initPos.xs1 = m_dXCenter;
200 m_initPos.ys1 = m_dYCenter + m_dFocalLength;;
201 m_initPos.xs2 = m_dXCenter;
202 m_initPos.ys2 = m_dYCenter + m_dFocalLength;
205 // Calculate incrementatal rotation matrix
207 xlat_mtx2 (m_rotmtxIncrement, -m_dXCenter, -m_dYCenter);
208 rot_mtx2 (temp, m_rotInc);
209 mult_mtx2 (m_rotmtxIncrement, temp, m_rotmtxIncrement);
210 xlat_mtx2 (temp, m_dXCenter, m_dYCenter);
211 mult_mtx2 (m_rotmtxIncrement, temp, m_rotmtxIncrement);
215 Scanner::~Scanner (void)
221 Scanner::convertGeometryIDToName (const int geomID)
223 const char *name = "";
225 if (geomID >= 0 && geomID < s_iGeometryCount)
226 return (s_aszGeometryName[geomID]);
232 Scanner::convertGeometryIDToTitle (const int geomID)
234 const char *title = "";
236 if (geomID >= 0 && geomID < s_iGeometryCount)
237 return (s_aszGeometryName[geomID]);
243 Scanner::convertGeometryNameToID (const char* const geomName)
245 int id = GEOMETRY_INVALID;
247 for (int i = 0; i < s_iGeometryCount; i++)
248 if (strcasecmp (geomName, s_aszGeometryName[i]) == 0) {
258 * collectProjections Calculate projections for a Phantom
261 * collectProjections (proj, phm, start_view, nView, bStoreViewPos, trace)
262 * Projectrions& proj Projection storage
263 * Phantom& phm Phantom for which we collect projections
264 * bool bStoreViewPos TRUE then storage proj at normal view position
265 * int trace Trace level
270 Scanner::collectProjections (Projections& proj, const Phantom& phm, const int trace, SGP* pSGP)
272 collectProjections (proj, phm, 0, proj.nView(), true, trace, pSGP);
276 Scanner::collectProjections (Projections& proj, const Phantom& phm, const int iStartView, const int iNumViews,
277 bool bStoreAtViewPosition, const int trace, SGP* pSGP)
279 int iStorageOffset = (bStoreAtViewPosition ? iStartView : 0);
280 collectProjections (proj, phm, iStartView, iNumViews, iStorageOffset, trace, pSGP);
284 Scanner::collectProjections (Projections& proj, const Phantom& phm, const int iStartView, const int iNumViews,
285 int iStorageOffset, const int trace, SGP* pSGP)
288 double start_angle = iStartView * proj.rotInc();
290 // Calculate initial rotation matrix
291 GRFMTX_2D rotmtx_initial, temp;
292 xlat_mtx2 (rotmtx_initial, -m_dXCenter, -m_dYCenter);
293 rot_mtx2 (temp, start_angle);
294 mult_mtx2 (rotmtx_initial, temp, rotmtx_initial);
295 xlat_mtx2 (temp, m_dXCenter, m_dYCenter);
296 mult_mtx2 (rotmtx_initial, temp, rotmtx_initial);
298 double xd1=0, yd1=0, xd2=0, yd2=0;
299 if (m_idGeometry != GEOMETRY_EQUIANGULAR) {
304 xform_mtx2 (rotmtx_initial, xd1, yd1); // rotate detector endpoints
305 xform_mtx2 (rotmtx_initial, xd2, yd2); // to initial view_angle
308 double xs1 = m_initPos.xs1;
309 double ys1 = m_initPos.ys1;
310 double xs2 = m_initPos.xs2;
311 double ys2 = m_initPos.ys2;
312 xform_mtx2 (rotmtx_initial, xs1, ys1); // rotate source endpoints to
313 xform_mtx2 (rotmtx_initial, xs2, ys2); // initial view angle
317 for (iView = 0, viewAngle = start_angle; iView < iNumViews; iView++, viewAngle += proj.rotInc()) {
318 int iStoragePosition = iView + iStorageOffset;
320 DetectorArray& detArray = proj.getDetectorArray( iStoragePosition );
323 if (pSGP && m_trace >= Trace::TRACE_PHANTOM) {
325 double dWindowSize = dmax (m_detLen, m_dSourceDetectorLength) * 2;
326 double dHalfWindowSize = dWindowSize / 2;
327 m_dXMinWin = m_dXCenter - dHalfWindowSize;
328 m_dXMaxWin = m_dXCenter + dHalfWindowSize;
329 m_dYMinWin = m_dYCenter - dHalfWindowSize;
330 m_dYMaxWin = m_dYCenter + dHalfWindowSize;
332 m_pSGP->setWindow (m_dXMinWin, m_dYMinWin, m_dXMaxWin, m_dYMaxWin);
333 m_pSGP->setRasterOp (RO_COPY);
335 m_pSGP->setColor (C_RED);
336 m_pSGP->moveAbs (0., 0.);
337 m_pSGP->drawCircle (m_dViewDiameter / 2);
339 m_pSGP->moveAbs (0., 0.);
340 m_pSGP->setColor (C_GREEN);
341 m_pSGP->drawCircle (m_dFocalLength);
342 m_pSGP->setColor (C_BLUE);
343 m_pSGP->setTextPointSize (9);
345 m_dTextHeight = m_pSGP->getCharHeight ();
347 traceShowParam ("Phantom:", "%s", PROJECTION_TRACE_ROW_PHANT_ID, C_BLACK, phm.name().c_str());
348 traceShowParam ("Geometry:", "%s", PROJECTION_TRACE_ROW_GEOMETRY, C_BLUE, convertGeometryIDToName(m_idGeometry));
349 traceShowParam ("Focal Length Ratio:", "%.2f", PROJECTION_TRACE_ROW_FOCAL_LENGTH, C_BLUE, m_dFocalLengthRatio);
350 // traceShowParam ("Field Of View Ratio:", "%.2f", PROJECTION_TRACE_ROW_FIELD_OF_VIEW, C_BLUE, m_dFieldOfViewRatio);
351 traceShowParam ("Num Detectors:", "%d", PROJECTION_TRACE_ROW_NDET, C_BLUE, proj.nDet());
352 traceShowParam ("Num Views:", "%d", PROJECTION_TRACE_ROW_NVIEW, C_BLUE, proj.nView());
353 traceShowParam ("Samples / Ray:", "%d", PROJECTION_TRACE_ROW_SAMPLES, C_BLUE, m_nSample);
355 m_pSGP->setMarker (SGP::MARK_BDIAMOND, C_LTGREEN);
360 if (m_pSGP && m_trace >= Trace::TRACE_PHANTOM) {
361 m_pSGP->setColor (C_BLACK);
362 m_pSGP->setPenWidth (2);
363 if (m_idGeometry == GEOMETRY_PARALLEL) {
364 m_pSGP->moveAbs (xs1, ys1);
365 m_pSGP->lineAbs (xs2, ys2);
366 m_pSGP->moveAbs (xd1, yd1);
367 m_pSGP->lineAbs (xd2, yd2);
368 } else if (m_idGeometry == GEOMETRY_EQUILINEAR) {
369 m_pSGP->setPenWidth (4);
370 m_pSGP->moveAbs (xs1, ys1);
371 m_pSGP->lineAbs (xs2, ys2);
372 m_pSGP->setPenWidth (2);
373 m_pSGP->moveAbs (xd1, yd1);
374 m_pSGP->lineAbs (xd2, yd2);
375 } else if (m_idGeometry == GEOMETRY_EQUIANGULAR) {
376 m_pSGP->setPenWidth (4);
377 m_pSGP->moveAbs (xs1, ys1);
378 m_pSGP->lineAbs (xs2, ys2);
379 m_pSGP->setPenWidth (2);
380 m_pSGP->moveAbs (0., 0.);
381 m_pSGP->drawArc (m_dCenterDetectorLength, viewAngle + 3 * HALFPI - (m_dAngularDetLen/2), viewAngle + 3 * HALFPI + (m_dAngularDetLen/2));
383 m_pSGP->setPenWidth (1);
385 if (m_trace > Trace::TRACE_CONSOLE)
386 traceShowParam ("Current View:", "%d (%.0f%%)", PROJECTION_TRACE_ROW_CURR_VIEW, C_RED, iView + iStartView, (iView + iStartView) / static_cast<double>(m_nView) * 100.);
388 if (m_trace == Trace::TRACE_CONSOLE)
389 std::cout << "Current View: " << iView+iStartView << std::endl;
391 projectSingleView (phm, detArray, xd1, yd1, xd2, yd2, xs1, ys1, xs2, ys2, viewAngle + 3 * HALFPI);
392 detArray.setViewAngle (viewAngle);
395 if (m_pSGP && m_trace >= Trace::TRACE_PHANTOM) {
396 // rs_plot (detArray, xd1, yd1, dXCenter, dYCenter, theta);
399 xform_mtx2 (m_rotmtxIncrement, xs1, ys1);
400 xform_mtx2 (m_rotmtxIncrement, xs2, ys2);
401 if (m_idGeometry != GEOMETRY_EQUIANGULAR) {
402 xform_mtx2 (m_rotmtxIncrement, xd1, yd1); // rotate detector endpoints
403 xform_mtx2 (m_rotmtxIncrement, xd2, yd2);
405 } /* for each iView */
410 * rayview Calculate raysums for a view at any angle
413 * rayview (phm, detArray, xd1, nSample, yd1, xd2, yd2, xs1, ys1, xs2, ys2)
414 * Phantom& phm Phantom to scan
415 * DETARRAY *detArray Storage of values for detector array
416 * Scanner& det Scanner parameters
417 * double xd1, yd1, xd2, yd2 Beginning & ending detector positions
418 * double xs1, ys1, xs2, ys2 Beginning & ending source positions
421 * For each detector, have there are a variable number of rays traced.
422 * The source of each ray is the center of the source x-ray cell. The
423 * detector positions are equally spaced within the cell
425 * The increments between rays are calculated so that the cells start
426 * at the beginning of a detector cell and they end on the endpoint
427 * of the cell. Thus, the last cell starts at (xd2-ddx),(yd2-ddy).
428 * The exception to this is if there is only one ray per detector.
429 * In that case, the detector position is the center of the detector cell.
433 Scanner::projectSingleView (const Phantom& phm, DetectorArray& detArray, const double xd1, const double yd1, const double xd2, const double yd2, const double xs1, const double ys1, const double xs2, const double ys2, const double dDetAngle)
436 double sdx = (xs2 - xs1) / detArray.nDet(); // change in coords
437 double sdy = (ys2 - ys1) / detArray.nDet(); // between source
438 double xs_maj = xs1 + (sdx / 2); // put ray source in center of cell
439 double ys_maj = ys1 + (sdy / 2);
441 double ddx=0, ddy=0, ddx2=0, ddy2=0, ddx2_ofs=0, ddy2_ofs=0, xd_maj=0, yd_maj=0;
442 double dAngleInc=0, dAngleSampleInc=0, dAngleSampleOffset=0, dAngleMajor=0;
443 if (m_idGeometry == GEOMETRY_EQUIANGULAR) {
444 dAngleInc = m_dAngularDetIncrement;
445 dAngleSampleInc = dAngleInc / m_nSample;
446 dAngleSampleOffset = dAngleSampleInc / 2;
447 dAngleMajor = dDetAngle - (m_dAngularDetLen/2) + dAngleSampleOffset;
449 ddx = (xd2 - xd1) / detArray.nDet(); // change in coords
450 ddy = (yd2 - yd1) / detArray.nDet(); // between detectors
451 ddx2 = ddx / m_nSample; // Incr. between rays with detector cell
452 ddy2 = ddy / m_nSample; // Doesn't include detector endpoints
453 ddx2_ofs = ddx2 / 2; // offset of 1st ray from start of detector cell
456 xd_maj = xd1 + ddx2_ofs; // Incr. between detector cells
457 yd_maj = yd1 + ddy2_ofs;
460 DetectorValue* detval = detArray.detValues();
462 if (phm.getComposition() == P_UNIT_PULSE) { // put unit pulse in center of view
463 for (int d = 0; d < detArray.nDet(); d++)
464 if (detArray.nDet() / 2 == d && (d % 2) == 1)
469 for (int d = 0; d < detArray.nDet(); d++) {
472 double xd=0, yd=0, dAngle=0;
473 if (m_idGeometry == GEOMETRY_EQUIANGULAR) {
474 dAngle = dAngleMajor;
480 for (unsigned int i = 0; i < m_nSample; i++) {
481 if (m_idGeometry == GEOMETRY_EQUIANGULAR) {
482 xd = m_dCenterDetectorLength * cos (dAngle);
483 yd = m_dCenterDetectorLength * sin (dAngle);
487 if (m_pSGP && m_trace >= Trace::TRACE_PROJECTIONS) {
488 m_pSGP->setColor (C_YELLOW);
489 m_pSGP->setRasterOp (RO_AND);
490 m_pSGP->moveAbs (xs, ys);
491 m_pSGP->lineAbs (xd, yd);
495 sum += projectSingleLine (phm, xd, yd, xs, ys);
498 // if (m_trace >= Trace::TRACE_CLIPPING) {
499 // traceShowParam ("Attenuation:", "%s", PROJECTION_TRACE_ROW_ATTEN, C_LTMAGENTA, " ");
500 // traceShowParam ("Attenuation:", "%.3f", PROJECTION_TRACE_ROW_ATTEN, C_LTMAGENTA, sum);
503 if (m_idGeometry == GEOMETRY_EQUIANGULAR)
504 dAngle += dAngleSampleInc;
509 } // for each sample in detector
511 detval[d] = sum / m_nSample;
514 if (m_idGeometry == GEOMETRY_EQUIANGULAR)
515 dAngleMajor += dAngleInc;
520 } /* for each detector */
521 } /* if not unit pulse */
526 Scanner::traceShowParam (const char *szLabel, const char *fmt, int row, int color, ...)
529 va_start(arg, color);
531 traceShowParamRasterOp (RO_COPY, szLabel, fmt, row, color, arg);
533 traceShowParamRasterOp (0, szLabel, fmt, row, color, arg);
539 Scanner::traceShowParamXOR (const char *szLabel, const char *fmt, int row, int color, ...)
542 va_start(arg, color);
544 traceShowParamRasterOp (RO_XOR, szLabel, fmt, row, color, arg);
546 traceShowParamRasterOp (0, szLabel, fmt, row, color, arg);
552 Scanner::traceShowParamRasterOp (int iRasterOp, const char *szLabel, const char *fmt, int row, int color, va_list args)
556 vsnprintf (szValue, sizeof(szValue), fmt, args);
560 m_pSGP->setRasterOp (iRasterOp);
561 m_pSGP->setTextColor (color, -1);
562 double dValueOffset = (m_dXMaxWin - m_dXMinWin) / 4;
564 double dYPos = m_dYMaxWin - (row * m_dTextHeight);
565 double dXPos = m_dXMinWin;
566 m_pSGP->moveAbs (dXPos, dYPos);
567 m_pSGP->drawText (szLabel);
568 m_pSGP->moveAbs (dXPos + dValueOffset, dYPos);
569 m_pSGP->drawText (szValue);
572 double dYPos = m_dYMaxWin - (row * m_dTextHeight);
573 double dXPos = m_dXMinWin + (m_dXMaxWin - m_dXMinWin) * 0.5;
574 m_pSGP->moveAbs (dXPos, dYPos);
575 m_pSGP->drawText (szLabel);
576 m_pSGP->moveAbs (dXPos + dValueOffset, dYPos);
577 m_pSGP->drawText (szValue);
582 cio_put_str (szLabel);
583 cio_put_str (szValue);
591 * projectSingleLine INTERNAL: Calculates raysum along a line for a Phantom
594 * rsum = phm_ray_attenuation (phm, x1, y1, x2, y2)
595 * double rsum Ray sum of Phantom along given line
596 * Phantom& phm; Phantom from which to calculate raysum
597 * double *x1, *y1, *x2, y2 Endpoints of ray path (in Phantom coords)
601 Scanner::projectSingleLine (const Phantom& phm, const double x1, const double y1, const double x2, const double y2)
603 // check ray against each pelem in Phantom
605 for (PElemConstIterator i = phm.listPElem().begin(); i != phm.listPElem().end(); i++)
606 rsum += projectLineAgainstPElem (**i, x1, y1, x2, y2);
613 * pelem_ray_attenuation Calculate raysum of an pelem along one line
616 * rsum = pelem_ray_attenuation (pelem, x1, y1, x2, y2)
617 * double rsum Computed raysum
618 * PhantomElement& pelem Pelem to scan
619 * double x1, y1, x2, y2 Endpoints of raysum line
623 Scanner::projectLineAgainstPElem (const PhantomElement& pelem, double x1, double y1, double x2, double y2)
625 if (! pelem.clipLineWorldCoords (x1, y1, x2, y2)) {
626 if (m_trace == Trace::TRACE_CLIPPING)
627 cio_tone (1000., 0.05);
632 if (m_pSGP && m_trace == Trace::TRACE_CLIPPING) {
633 m_pSGP->setRasterOp (RO_XOR);
634 m_pSGP->moveAbs (x1, y1);
635 m_pSGP->lineAbs (x2, y2);
636 cio_tone (8000., 0.05);
637 m_pSGP->moveAbs (x1, y1);
638 m_pSGP->lineAbs (x2, y2);
639 m_pSGP->setRasterOp (RO_SET);
643 double len = lineLength (x1, y1, x2, y2);
644 return (len * pelem.atten());