CSCWireGeometry.cc

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#include "Geometry/CSCGeometry/interface/CSCWireGeometry.h"

#include <FWCore/MessageLogger/interface/MessageLogger.h>

#include <cmath>

LocalPoint CSCWireGeometry::intersection(float m1, float c1, float m2, float c2) const {
  // Calculate the point of intersection of two straight lines (in 2-dim)
  // BEWARE! Do not call with m1 = m2 ! No trapping !

  float x = (c2 - c1) / (m1 - m2);
  float y = (m1 * c2 - m2 * c1) / (m1 - m2);
  return LocalPoint(x, y);
}

std::vector<float> CSCWireGeometry::wireValues(float wire) const {
  // return x and y of mid-point of wire, and length of wire, as 3-dim vector.
  // If wire does not intersect active area the returned vector is filled with 0's.

  std::pair<LocalPoint, LocalPoint> ends = wireEnds(wire);

  std::vector<float> buf(3);  // note all elem init to 0

  buf[0] = (ends.first.x() + ends.second.x()) / 2.;  // x is first elem of first & second pairs
  buf[1] = (ends.first.y() + ends.second.y()) / 2.;  // y is second elem of first & second pairs
  float d2 = (ends.first.x() - ends.second.x()) * (ends.first.x() - ends.second.x()) +
             (ends.first.y() - ends.second.y()) * (ends.first.y() - ends.second.y());
  buf[2] = sqrt(d2);
  return buf;
}

std::pair<LocalPoint, LocalPoint> CSCWireGeometry::wireEnds(float wire) const {
  // return local (x, y) of each end of wire.
  // If wire does not intersect active area set all values to 0.

  const float fprec = 1.E-06;

  // slope of wire
  float wangle = wireAngle();
  float mw = 0;
  if (fabs(wangle) > fprec)
    mw = tan(wireAngle());

  // intercept of wire
  float cw = yOfWire(wire);

  LogTrace("CSCWireGeometry|CSC") << "CSCWireGeometry: wire=" << wire << ", wire angle = " << wangle
                                  << ", intercept on y axis=" << cw;

  // Find extent of wire plane
  double ww = wideWidthOfPlane();
  double nw = narrowWidthOfPlane();
  double len = lengthOfPlane();

  // slope & intercept of line defining one non-parallel edge of wire-plane trapezoid
  float m1 = 2. * len / (ww - nw);
  float c1 = 0.;
  if (fabs(wangle) < fprec) {
    c1 = yOfFirstWire() - nw * len / (ww - nw);  // non-ME11
  } else {
    c1 = -len / 2. - nw * len / (ww - nw);  // ME11
  }

  // slope & intercept of other non-parallel edge of wire-plane trapezoid
  float m2 = -m1;
  float c2 = c1;

  // wire intersects edge 1 at
  LocalPoint pw1 = intersection(mw, cw, m1, c1);
  // wire intersects edge 2 at
  LocalPoint pw2 = intersection(mw, cw, m2, c2);

  float x1 = pw1.x();
  float y1 = pw1.y();

  float x2 = pw2.x();
  float y2 = pw2.y();

  LogTrace("CSCWireGeometry|CSC") << "CSCWireGeometry: wire intersects edges of plane at "
                                  << "\n  x1=" << x1 << " y1=" << y1 << " x2=" << x2 << " y2=" << y2;

  // WIRES ARE NOT TILTED?

  if (fabs(wangle) < fprec) {
    LogTrace("CSCWireGeometry|CSC") << "CSCWireGeometry: wires are not tilted ";
    return std::pair<LocalPoint, LocalPoint>(LocalPoint(x1, y1), LocalPoint(x2, y2));
  }

  // WIRES ARE TILTED

  // ht and hb will be used to check where wire intersects edges of wire plane
  float ht = ww / 2.;
  float hb = nw / 2.;
  float mt = 0.;         // slope of top edge
  float mb = 0.;         //slope of bottom edge
  float cb = -len / 2.;  // intercept bottom edge of wire plane
  float ct = len / 2.;   // intercept top edge of wire plane

  LogTrace("CSCWireGeometry|CSC") << "CSCWireGeometry: slopes & intercepts "
                                  << "\n  mt=" << mt << " ct=" << ct << " mb=" << mb << " cb=" << cb << "\n  m1=" << m1
                                  << " c1=" << c1 << " m2=" << m2 << " c2=" << c2 << "\n  mw=" << mw << " cw=" << cw;

  // wire intersects top edge at
  LocalPoint pwt = intersection(mw, cw, mt, ct);
  // wire intersects bottom edge at
  LocalPoint pwb = intersection(mw, cw, mb, cb);

  // get the local coordinates
  float xt = pwt.x();
  float yt = pwt.y();

  float xb = pwb.x();
  float yb = pwb.y();

  LogTrace("CSCWireGeometry|CSC") << "CSCWireGeometry: wire intersects top & bottom of wire plane at "
                                  << "\n  xt=" << xt << " yt=" << yt << " xb=" << xb << " yb=" << yb;

  float xWireEnd[4], yWireEnd[4];

  int i = 0;
  if (fabs(x1) >= hb && fabs(x1) <= ht) {
    // wire does intersect side edge 1 of wire plane
    xWireEnd[i] = x1;
    yWireEnd[i] = y1;
    i++;
  }
  if (fabs(xb) <= hb) {
    // wire does intersect bottom edge of wire plane
    xWireEnd[i] = xb;
    yWireEnd[i] = yb;
    i++;
  }
  if (fabs(x2) >= hb && fabs(x2) <= ht) {
    // wire does intersect side edge 2 of wire plane
    xWireEnd[i] = x2;
    yWireEnd[i] = y2;
    i++;
  }
  if (fabs(xt) <= ht) {
    // wire does intersect top edge of wire plane
    xWireEnd[i] = xt;
    yWireEnd[i] = yt;
    i++;
  }

  if (i != 2) {
    // the wire does not intersect the wire plane (!)

    LogTrace("CSCWireGeometry|CSC") << "CSCWireGeometry: wire does not intersect wire plane!!";
    //     throw cms::Exception("BadCSCGeometry") << "the wire has " << i <<
    //       " ends!" << "\n";

    return std::pair<LocalPoint, LocalPoint>(LocalPoint(0., 0.), LocalPoint(0., 0.));
  }

  LogTrace("CSCWireGeometry|CSC") << "CSCWireGeometry: ME11 wire ends ";
  for (int j = 0; j < i; j++) {
    LogTrace("CSCWireGeometry|CSC") << "  x = " << xWireEnd[j] << " y = " << yWireEnd[j];
  }

  return std::pair<LocalPoint, LocalPoint>(LocalPoint(xWireEnd[0], yWireEnd[0]), LocalPoint(xWireEnd[1], yWireEnd[1]));
}

//@@ COULD/SHOULD BE IMPLEMENTED IN Slanted & Nonslanted DERIVED CLASSES

std::pair<float, float> CSCWireGeometry::equationOfWire(float wire) const {
  const float fprec = 1.E-06;

  // slope of wire
  float wangle = wireAngle();
  float mw = 0;
  if (fabs(wangle) > fprec)
    mw = tan(wangle);

  // intercept of wire
  float cw = yOfWire(wire);

  LogTrace("CSCWireGeometry|CSC") << "CSCWireGeometry: wire=" << wire << ", wire angle = " << wangle
                                  << ", intercept on y axis=" << cw;

  return std::pair<float, float>(mw, cw);
}

//@@ COULD/SHOULD BE IMPLEMENTED IN Slanted & Nonslanted DERIVED CLASSES

std::pair<float, float> CSCWireGeometry::yLimitsOfWirePlane() const {
  const float fprec = 0.1;      // wire angle is either 0 or 29 degrees = 0.506 rads
  float ylow = yOfFirstWire();  // non-ME11 chambers
  float wangle = wireAngle();
  if (fabs(wangle) > fprec) {
    ylow += tan(std::abs(wangle)) * narrowWidthOfPlane() / 2.;  // correction for ME11
  }
  float yhigh = ylow + lengthOfPlane();  // add extent of wire plane in y

  return std::pair<float, float>(ylow, yhigh);
}