1 /*****************************************************************************
5 ** Purpose: Classes for CT scanner
6 ** Programmer: Kevin Rosenberg
9 ** This is part of the CTSim program
10 ** Copyright (c) 1983-2009 Kevin Rosenberg
12 ** This program is free software; you can redistribute it and/or modify
13 ** it under the terms of the GNU General Public License (version 2) as
14 ** published by the Free Software Foundation.
16 ** This program is distributed in the hope that it will be useful,
17 ** but WITHOUT ANY WARRANTY; without even the implied warranty of
18 ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 ** GNU General Public License for more details.
21 ** You should have received a copy of the GNU General Public License
22 ** along with this program; if not, write to the Free Software
23 ** Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
24 ******************************************************************************/
29 const int Scanner::GEOMETRY_INVALID = -1;
30 const int Scanner::GEOMETRY_PARALLEL = 0;
31 const int Scanner::GEOMETRY_EQUIANGULAR = 1;
32 const int Scanner::GEOMETRY_EQUILINEAR = 2;
33 const int Scanner::GEOMETRY_LINOGRAM = 3;
35 const char* const Scanner::s_aszGeometryName[] =
43 const char* const Scanner::s_aszGeometryTitle[] =
51 const int Scanner::s_iGeometryCount = sizeof(s_aszGeometryName) / sizeof(const char*);
55 // DetectorArray Construct a DetectorArray
57 DetectorArray::DetectorArray (const int nDet)
60 m_detValues = new DetectorValue [m_nDet];
65 // ~DetectorArray Free memory allocated to a detector array
67 DetectorArray::~DetectorArray (void)
69 delete [] m_detValues;
75 * Scanner::Scanner Construct a user specified detector structure
78 * Scanner (phm, nDet, nView, nSample)
79 * Phantom& phm PHANTOM that we are making detector for
80 * int geomety Geometry of detector
81 * int nDet Number of detector along detector array
82 * int nView Number of rotated views
83 * int nSample Number of rays per detector
86 Scanner::Scanner (const Phantom& phm, const char* const geometryName,
87 int nDet, int nView, int offsetView,
88 int nSample, const double rot_anglen,
89 const double dFocalLengthRatio,
90 const double dCenterDetectorRatio,
91 const double dViewRatio, const double dScanRatio)
94 m_idGeometry = convertGeometryNameToID (geometryName);
95 if (m_idGeometry == GEOMETRY_INVALID) {
97 m_failMessage = "Invalid geometry name ";
98 m_failMessage += geometryName;
102 if (nView < 1 || nDet < 1) {
104 m_failMessage = "nView & nDet must be greater than 0";
112 m_iOffsetView = offsetView;
114 m_dFocalLengthRatio = dFocalLengthRatio;
115 m_dCenterDetectorRatio = dCenterDetectorRatio;
116 m_dViewRatio = dViewRatio;
117 m_dScanRatio = dScanRatio;
119 m_dViewDiameter = phm.getDiameterBoundaryCircle() * m_dViewRatio;
120 m_dFocalLength = (m_dViewDiameter / 2) * m_dFocalLengthRatio;
121 m_dCenterDetectorLength = (m_dViewDiameter / 2) * m_dCenterDetectorRatio;
122 m_dSourceDetectorLength = m_dFocalLength + m_dCenterDetectorLength;
123 m_dScanDiameter = m_dViewDiameter * m_dScanRatio;
125 m_dXCenter = phm.xmin() + (phm.xmax() - phm.xmin()) / 2;
126 m_dYCenter = phm.ymin() + (phm.ymax() - phm.ymin()) / 2;
127 m_rotLen = rot_anglen;
128 m_rotInc = m_rotLen / m_nView;
129 if (m_idGeometry == GEOMETRY_PARALLEL) {
131 m_detLen = m_dScanDiameter;
132 m_detStart = -m_detLen / 2;
133 m_detInc = m_detLen / m_nDet;
134 double dDetectorArrayEndOffset = 0;
135 // For even number of detectors, make detInc slightly larger so that center lies
136 // at nDet/2. Also, extend detector array by one detInc so that all of the phantom is scanned
137 if (isEven (m_nDet)) { // Adjust for Even number of detectors
138 m_detInc = m_detLen / (m_nDet - 1); // center detector = (nDet/2)
139 dDetectorArrayEndOffset = m_detInc;
142 double dHalfDetLen = m_detLen / 2;
143 m_initPos.xs1 = m_dXCenter - dHalfDetLen;
144 m_initPos.ys1 = m_dYCenter + m_dFocalLength;
145 m_initPos.xs2 = m_dXCenter + dHalfDetLen + dDetectorArrayEndOffset;
146 m_initPos.ys2 = m_dYCenter + m_dFocalLength;
147 m_initPos.xd1 = m_dXCenter - dHalfDetLen;
148 m_initPos.yd1 = m_dYCenter - m_dCenterDetectorLength;
149 m_initPos.xd2 = m_dXCenter + dHalfDetLen + dDetectorArrayEndOffset;
150 m_initPos.yd2 = m_dYCenter - m_dCenterDetectorLength;
151 m_initPos.angle = m_iOffsetView * m_rotInc;
152 m_detLen += dDetectorArrayEndOffset;
153 } else if (m_idGeometry == GEOMETRY_EQUILINEAR) {
154 if (m_dScanDiameter / 2 >= m_dFocalLength) {
156 m_failMessage = "Invalid geometry: Focal length must be larger than scan length";
160 const double dAngle = asin ((m_dScanDiameter / 2) / m_dFocalLength);
161 const double dHalfDetLen = m_dSourceDetectorLength * tan (dAngle);
163 m_detLen = dHalfDetLen * 2;
164 m_detStart = -dHalfDetLen;
165 m_detInc = m_detLen / m_nDet;
166 double dDetectorArrayEndOffset = 0;
167 if (isEven (m_nDet)) { // Adjust for Even number of detectors
168 m_detInc = m_detLen / (m_nDet - 1); // center detector = (nDet/2)
169 dDetectorArrayEndOffset = m_detInc;
170 m_detLen += dDetectorArrayEndOffset;
173 m_dFanBeamAngle = dAngle * 2;
174 m_initPos.xs1 = m_dXCenter;
175 m_initPos.ys1 = m_dYCenter + m_dFocalLength;
176 m_initPos.xs2 = m_dXCenter;
177 m_initPos.ys2 = m_dYCenter + m_dFocalLength;
178 m_initPos.xd1 = m_dXCenter - dHalfDetLen;
179 m_initPos.yd1 = m_dYCenter - m_dCenterDetectorLength;
180 m_initPos.xd2 = m_dXCenter + dHalfDetLen + dDetectorArrayEndOffset;
181 m_initPos.yd2 = m_dYCenter - m_dCenterDetectorLength;
182 m_initPos.angle = m_iOffsetView * m_rotInc;
183 } else if (m_idGeometry == GEOMETRY_EQUIANGULAR) {
184 if (m_dScanDiameter / 2 > m_dFocalLength) {
186 m_failMessage = "Invalid geometry: Focal length must be larger than scan length";
189 const double dAngle = asin ((m_dScanDiameter / 2) / m_dFocalLength);
191 m_detLen = 2 * dAngle;
192 m_detStart = -dAngle;
193 m_detInc = m_detLen / m_nDet;
194 double dDetectorArrayEndOffset = 0;
195 if (isEven (m_nDet)) { // Adjust for Even number of detectors
196 m_detInc = m_detLen / (m_nDet - 1); // center detector = (nDet/2)
197 dDetectorArrayEndOffset = m_detInc;
199 // adjust for center-detector length
200 double dA1 = acos ((m_dScanDiameter / 2) / m_dCenterDetectorLength);
201 double dAngularScale = 2 * (HALFPI + dAngle - dA1) / m_detLen;
203 m_dAngularDetLen = dAngularScale * (m_detLen + dDetectorArrayEndOffset);
204 m_dAngularDetIncrement = dAngularScale * m_detInc;
205 m_initPos.dAngularDet = -m_dAngularDetLen / 2;
207 m_dFanBeamAngle = dAngle * 2;
208 m_initPos.angle = m_iOffsetView * m_rotInc;
209 m_initPos.xs1 = m_dXCenter;
210 m_initPos.ys1 = m_dYCenter + m_dFocalLength;;
211 m_initPos.xs2 = m_dXCenter;
212 m_initPos.ys2 = m_dYCenter + m_dFocalLength;
213 m_detLen += dDetectorArrayEndOffset;
216 // Calculate incrementatal rotation matrix
218 xlat_mtx2 (m_rotmtxIncrement, -m_dXCenter, -m_dYCenter);
219 rot_mtx2 (temp, m_rotInc);
220 mult_mtx2 (m_rotmtxIncrement, temp, m_rotmtxIncrement);
221 xlat_mtx2 (temp, m_dXCenter, m_dYCenter);
222 mult_mtx2 (m_rotmtxIncrement, temp, m_rotmtxIncrement);
226 Scanner::~Scanner (void)
232 Scanner::convertGeometryIDToName (const int geomID)
234 const char *name = "";
236 if (geomID >= 0 && geomID < s_iGeometryCount)
237 return (s_aszGeometryName[geomID]);
243 Scanner::convertGeometryIDToTitle (const int geomID)
245 const char *title = "";
247 if (geomID >= 0 && geomID < s_iGeometryCount)
248 return (s_aszGeometryName[geomID]);
254 Scanner::convertGeometryNameToID (const char* const geomName)
256 int id = GEOMETRY_INVALID;
258 for (int i = 0; i < s_iGeometryCount; i++) {
259 if (strcasecmp (geomName, s_aszGeometryName[i]) == 0) {
269 * collectProjections Calculate projections for a Phantom
272 * collectProjections (proj, phm, start_view, nView, bStoreViewPos, trace)
273 * Projectrions& proj Projection storage
274 * Phantom& phm Phantom for which we collect projections
275 * bool bStoreViewPos TRUE then storage proj at normal view position
276 * int trace Trace level
281 Scanner::collectProjections (Projections& proj, const Phantom& phm, const int trace, SGP* pSGP)
283 collectProjections (proj, phm, m_startView, proj.nView(), m_iOffsetView, true, trace, pSGP);
287 Scanner::collectProjections (Projections& proj, const Phantom& phm, const int iStartView,
288 const int iNumViews, const int iOffsetView, bool bStoreAtViewPosition,
289 const int trace, SGP* pSGP)
291 int iStorageOffset = (bStoreAtViewPosition ? iStartView : 0);
292 collectProjections (proj, phm, iStartView, iNumViews, iOffsetView, iStorageOffset, trace, pSGP);
295 static void mtx2_offset_rot (GRFMTX_2D m, double angle, double x, double y) {
297 xlat_mtx2 (m, -x, -y);
298 rot_mtx2 (temp, angle);
299 mult_mtx2 (m, temp, m);
300 xlat_mtx2 (temp, x, y);
301 mult_mtx2 (m, temp, m);
305 Scanner::collectProjections (Projections& proj, const Phantom& phm, const int iStartView,
306 const int iNumViews, const int iOffsetView, int iStorageOffset,
307 const int trace, SGP* pSGP)
310 double start_angle = (iStartView + iOffsetView) * proj.rotInc();
313 #pragma omp parallel for
316 for (int iView = 0; iView < iNumViews; iView++) {
317 double viewAngle = start_angle + (iView * proj.rotInc());
319 // With OpenMP, need to calculate source and detector positions at each view
321 mtx2_offset_rot (rotmtx, viewAngle, m_dXCenter, m_dYCenter);
322 double xd1=0, yd1=0, xd2=0, yd2=0;
323 if (m_idGeometry != GEOMETRY_EQUIANGULAR) {
324 xd1 = m_initPos.xd1; yd1 = m_initPos.yd1;
325 xd2 = m_initPos.xd2; yd2 = m_initPos.yd2;
326 xform_mtx2 (rotmtx, xd1, yd1); // rotate detector endpoints
327 xform_mtx2 (rotmtx, xd2, yd2); // to initial view_angle
330 double xs1 = m_initPos.xs1, ys1 = m_initPos.ys1;
331 double xs2 = m_initPos.xs2, ys2 = m_initPos.ys2;
332 xform_mtx2 (rotmtx, xs1, ys1); // rotate source endpoints to
333 xform_mtx2 (rotmtx, xs2, ys2); // initial view angle
335 int iStoragePosition = iView + iStorageOffset;
336 DetectorArray& detArray = proj.getDetectorArray( iStoragePosition );
339 if (pSGP && m_trace >= Trace::TRACE_PHANTOM) {
341 double dWindowSize = dmax (m_detLen, m_dSourceDetectorLength) * 2;
342 double dHalfWindowSize = dWindowSize / 2;
343 m_dXMinWin = m_dXCenter - dHalfWindowSize;
344 m_dXMaxWin = m_dXCenter + dHalfWindowSize;
345 m_dYMinWin = m_dYCenter - dHalfWindowSize;
346 m_dYMaxWin = m_dYCenter + dHalfWindowSize;
348 m_pSGP->setWindow (m_dXMinWin, m_dYMinWin, m_dXMaxWin, m_dYMaxWin);
349 m_pSGP->setRasterOp (RO_COPY);
351 m_pSGP->setColor (C_RED);
352 m_pSGP->moveAbs (0., 0.);
353 m_pSGP->drawCircle (m_dViewDiameter / 2);
355 m_pSGP->moveAbs (0., 0.);
356 m_pSGP->setColor (C_GREEN);
357 m_pSGP->drawCircle (m_dFocalLength);
358 m_pSGP->setColor (C_BLUE);
359 m_pSGP->setTextPointSize (9);
361 m_dTextHeight = m_pSGP->getCharHeight ();
363 traceShowParam ("Phantom:", "%s", PROJECTION_TRACE_ROW_PHANT_ID, C_BLACK, phm.name().c_str());
364 traceShowParam ("Geometry:", "%s", PROJECTION_TRACE_ROW_GEOMETRY, C_BLUE, convertGeometryIDToName(m_idGeometry));
365 traceShowParam ("Focal Length Ratio:", "%.2f", PROJECTION_TRACE_ROW_FOCAL_LENGTH, C_BLUE, m_dFocalLengthRatio);
366 // traceShowParam ("Field Of View Ratio:", "%.2f", PROJECTION_TRACE_ROW_FIELD_OF_VIEW, C_BLUE, m_dFieldOfViewRatio);
367 traceShowParam ("Num Detectors:", "%d", PROJECTION_TRACE_ROW_NDET, C_BLUE, proj.nDet());
368 traceShowParam ("Num Views:", "%d", PROJECTION_TRACE_ROW_NVIEW, C_BLUE, proj.nView());
369 traceShowParam ("Samples / Ray:", "%d", PROJECTION_TRACE_ROW_SAMPLES, C_BLUE, m_nSample);
371 m_pSGP->setMarker (SGP::MARKER_BDIAMOND);
374 m_pSGP->setColor (C_BLACK);
375 m_pSGP->setPenWidth (2);
376 if (m_idGeometry == GEOMETRY_PARALLEL) {
377 m_pSGP->moveAbs (xs1, ys1);
378 m_pSGP->lineAbs (xs2, ys2);
379 m_pSGP->moveAbs (xd1, yd1);
380 m_pSGP->lineAbs (xd2, yd2);
381 } else if (m_idGeometry == GEOMETRY_EQUILINEAR) {
382 m_pSGP->setPenWidth (4);
383 m_pSGP->moveAbs (xs1, ys1);
384 m_pSGP->lineAbs (xs2, ys2);
385 m_pSGP->setPenWidth (2);
386 m_pSGP->moveAbs (xd1, yd1);
387 m_pSGP->lineAbs (xd2, yd2);
388 } else if (m_idGeometry == GEOMETRY_EQUIANGULAR) {
389 m_pSGP->setPenWidth (4);
390 m_pSGP->moveAbs (xs1, ys1);
391 m_pSGP->lineAbs (xs2, ys2);
392 m_pSGP->setPenWidth (2);
393 m_pSGP->moveAbs (0., 0.);
394 m_pSGP->drawArc (m_dCenterDetectorLength, viewAngle + 3 * HALFPI - (m_dAngularDetLen/2), viewAngle + 3 * HALFPI + (m_dAngularDetLen/2));
396 m_pSGP->setPenWidth (1);
398 if (m_trace > Trace::TRACE_CONSOLE)
399 traceShowParam ("Current View:", "%d (%.0f%%)", PROJECTION_TRACE_ROW_CURR_VIEW, C_RED, iView + iStartView, (iView + iStartView) / static_cast<double>(m_nView) * 100.);
402 if (m_trace == Trace::TRACE_CONSOLE)
403 std::cout << "Current View: " << iView+iStartView << std::endl;
405 projectSingleView (phm, detArray, xd1, yd1, xd2, yd2, xs1, ys1, xs2, ys2, viewAngle + 3 * HALFPI);
406 detArray.setViewAngle (viewAngle);
409 if (m_pSGP && m_trace >= Trace::TRACE_PHANTOM) {
410 // rs_plot (detArray, xd1, yd1, dXCenter, dYCenter, theta);
414 } /* for each iView */
419 * rayview Calculate raysums for a view at any angle
422 * rayview (phm, detArray, xd1, nSample, yd1, xd2, yd2, xs1, ys1, xs2, ys2)
423 * Phantom& phm Phantom to scan
424 * DETARRAY *detArray Storage of values for detector array
425 * Scanner& det Scanner parameters
426 * double xd1, yd1, xd2, yd2 Beginning & ending detector positions
427 * double xs1, ys1, xs2, ys2 Beginning & ending source positions
430 * For each detector, have there are a variable number of rays traced.
431 * The source of each ray is the center of the source x-ray cell. The
432 * detector positions are equally spaced within the cell
434 * The increments between rays are calculated so that the cells start
435 * at the beginning of a detector cell and they end on the endpoint
436 * of the cell. Thus, the last cell starts at (xd2-ddx),(yd2-ddy).
437 * The exception to this is if there is only one ray per detector.
438 * In that case, the detector position is the center of the detector cell.
442 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)
445 double sdx = (xs2 - xs1) / detArray.nDet(); // change in coords
446 double sdy = (ys2 - ys1) / detArray.nDet(); // between source
447 double xs_maj = xs1 + (sdx / 2); // put ray source in center of cell
448 double ys_maj = ys1 + (sdy / 2);
450 double ddx=0, ddy=0, ddx2=0, ddy2=0, ddx2_ofs=0, ddy2_ofs=0, xd_maj=0, yd_maj=0;
451 double dAngleInc=0, dAngleSampleInc=0, dAngleSampleOffset=0, dAngleMajor=0;
452 if (m_idGeometry == GEOMETRY_EQUIANGULAR) {
453 dAngleInc = m_dAngularDetIncrement;
454 dAngleSampleInc = dAngleInc / m_nSample;
455 dAngleSampleOffset = dAngleSampleInc / 2;
456 dAngleMajor = dDetAngle - (m_dAngularDetLen/2) + dAngleSampleOffset;
458 ddx = (xd2 - xd1) / detArray.nDet(); // change in coords
459 ddy = (yd2 - yd1) / detArray.nDet(); // between detectors
460 ddx2 = ddx / m_nSample; // Incr. between rays with detector cell
461 ddy2 = ddy / m_nSample; // Doesn't include detector endpoints
462 ddx2_ofs = ddx2 / 2; // offset of 1st ray from start of detector cell
465 xd_maj = xd1 + ddx2_ofs; // Incr. between detector cells
466 yd_maj = yd1 + ddy2_ofs;
469 DetectorValue* detval = detArray.detValues();
471 if (phm.getComposition() == P_UNIT_PULSE) { // put unit pulse in center of view
472 for (int d = 0; d < detArray.nDet(); d++)
474 detval[ detArray.nDet() / 2 ] = 1;
476 for (int d = 0; d < detArray.nDet(); d++) {
479 double xd=0, yd=0, dAngle=0;
480 if (m_idGeometry == GEOMETRY_EQUIANGULAR) {
481 dAngle = dAngleMajor;
487 for (unsigned int i = 0; i < m_nSample; i++) {
488 if (m_idGeometry == GEOMETRY_EQUIANGULAR) {
489 xd = m_dCenterDetectorLength * cos (dAngle);
490 yd = m_dCenterDetectorLength * sin (dAngle);
494 if (m_pSGP && m_trace >= Trace::TRACE_PROJECTIONS) {
495 m_pSGP->setColor (C_YELLOW);
496 m_pSGP->setRasterOp (RO_AND);
497 m_pSGP->moveAbs (xs, ys);
498 m_pSGP->lineAbs (xd, yd);
502 sum += projectSingleLine (phm, xd, yd, xs, ys);
505 // if (m_trace >= Trace::TRACE_CLIPPING) {
506 // traceShowParam ("Attenuation:", "%s", PROJECTION_TRACE_ROW_ATTEN, C_LTMAGENTA, " ");
507 // traceShowParam ("Attenuation:", "%.3f", PROJECTION_TRACE_ROW_ATTEN, C_LTMAGENTA, sum);
510 if (m_idGeometry == GEOMETRY_EQUIANGULAR)
511 dAngle += dAngleSampleInc;
516 } // for each sample in detector
518 detval[d] = sum / m_nSample;
521 if (m_idGeometry == GEOMETRY_EQUIANGULAR)
522 dAngleMajor += dAngleInc;
527 } /* for each detector */
528 } /* if not unit pulse */
533 Scanner::traceShowParam (const char *szLabel, const char *fmt, int row, int color, ...)
536 va_start(arg, color);
538 traceShowParamRasterOp (RO_COPY, szLabel, fmt, row, color, arg);
540 traceShowParamRasterOp (0, szLabel, fmt, row, color, arg);
546 Scanner::traceShowParamXOR (const char *szLabel, const char *fmt, int row, int color, ...)
549 va_start(arg, color);
551 traceShowParamRasterOp (RO_XOR, szLabel, fmt, row, color, arg);
553 traceShowParamRasterOp (0, szLabel, fmt, row, color, arg);
559 Scanner::traceShowParamRasterOp (int iRasterOp, const char *szLabel, const char *fmt, int row, int color, va_list args)
563 vsnprintf (szValue, sizeof(szValue), fmt, args);
567 m_pSGP->setRasterOp (iRasterOp);
568 m_pSGP->setTextColor (color, -1);
569 double dValueOffset = (m_dXMaxWin - m_dXMinWin) / 4;
571 double dYPos = m_dYMaxWin - (row * m_dTextHeight);
572 double dXPos = m_dXMinWin;
573 m_pSGP->moveAbs (dXPos, dYPos);
574 m_pSGP->drawText (szLabel);
575 m_pSGP->moveAbs (dXPos + dValueOffset, dYPos);
576 m_pSGP->drawText (szValue);
579 double dYPos = m_dYMaxWin - (row * m_dTextHeight);
580 double dXPos = m_dXMinWin + (m_dXMaxWin - m_dXMinWin) * 0.5;
581 m_pSGP->moveAbs (dXPos, dYPos);
582 m_pSGP->drawText (szLabel);
583 m_pSGP->moveAbs (dXPos + dValueOffset, dYPos);
584 m_pSGP->drawText (szValue);
589 cio_put_str (szLabel);
590 cio_put_str (szValue);
598 * projectSingleLine INTERNAL: Calculates raysum along a line for a Phantom
601 * rsum = phm_ray_attenuation (phm, x1, y1, x2, y2)
602 * double rsum Ray sum of Phantom along given line
603 * Phantom& phm; Phantom from which to calculate raysum
604 * double *x1, *y1, *x2, y2 Endpoints of ray path (in Phantom coords)
608 Scanner::projectSingleLine (const Phantom& phm, const double x1, const double y1, const double x2, const double y2)
610 // check ray against each pelem in Phantom
612 for (PElemConstIterator i = phm.listPElem().begin(); i != phm.listPElem().end(); i++)
613 rsum += projectLineAgainstPElem (**i, x1, y1, x2, y2);
620 * pelem_ray_attenuation Calculate raysum of an pelem along one line
623 * rsum = pelem_ray_attenuation (pelem, x1, y1, x2, y2)
624 * double rsum Computed raysum
625 * PhantomElement& pelem Pelem to scan
626 * double x1, y1, x2, y2 Endpoints of raysum line
630 Scanner::projectLineAgainstPElem (const PhantomElement& pelem, double x1, double y1, double x2, double y2)
632 if (! pelem.clipLineWorldCoords (x1, y1, x2, y2)) {
633 if (m_trace == Trace::TRACE_CLIPPING)
634 cio_tone (1000., 0.05);
639 if (m_pSGP && m_trace == Trace::TRACE_CLIPPING) {
640 m_pSGP->setRasterOp (RO_XOR);
641 m_pSGP->moveAbs (x1, y1);
642 m_pSGP->lineAbs (x2, y2);
643 cio_tone (8000., 0.05);
644 m_pSGP->moveAbs (x1, y1);
645 m_pSGP->lineAbs (x2, y2);
646 m_pSGP->setRasterOp (RO_SET);
650 double len = lineLength (x1, y1, x2, y2);
651 return (len * pelem.atten());