// Filename: piecewiseCurve.cxx
// Created by:  drose (04Mar01)
//
////////////////////////////////////////////////////////////////////
//
// PANDA 3D SOFTWARE
// Copyright (c) 2001 - 2004, Disney Enterprises, Inc.  All rights reserved
//
// All use of this software is subject to the terms of the Panda 3d
// Software license.  You should have received a copy of this license
// along with this source code; you will also find a current copy of
// the license at http://etc.cmu.edu/panda3d/docs/license/ .
//
// To contact the maintainers of this program write to
// panda3d-general@lists.sourceforge.net .
//
////////////////////////////////////////////////////////////////////

#include "piecewiseCurve.h"
#include "cubicCurveseg.h"
#include "config_parametrics.h"

#include "datagram.h"
#include "datagramIterator.h"
#include "bamWriter.h"
#include "bamReader.h"

TypeHandle PiecewiseCurve::_type_handle;

////////////////////////////////////////////////////////////////////
//     Function: PiecewiseCurve::Constructor
//       Access: Public
//  Description:
////////////////////////////////////////////////////////////////////
PiecewiseCurve::
PiecewiseCurve() {
  _last_ti = 0;
}

////////////////////////////////////////////////////////////////////
//     Function: PiecewiseCurve::Destructor
//       Access: Protected
//  Description:
////////////////////////////////////////////////////////////////////
PiecewiseCurve::
~PiecewiseCurve() {
  remove_all_curvesegs();
}


////////////////////////////////////////////////////////////////////
//     Function: PiecewiseCurve::is_valid
//       Access: Published, Virtual
//  Description: Returns true if the curve is defined.  In the case of
//               a PiecewiseCurve, this means we have at least one
//               segment.
////////////////////////////////////////////////////////////////////
bool PiecewiseCurve::
is_valid() const {
  return !_segs.empty();
}

////////////////////////////////////////////////////////////////////
//     Function: PiecewiseCurve::get_max_t
//       Access: Published, Virtual
//  Description: Returns the upper bound of t for the entire curve.
//               The curve is defined in the range 0.0f <= t <=
//               get_max_t().
////////////////////////////////////////////////////////////////////
float PiecewiseCurve::
get_max_t() const {
  return _segs.empty() ? 0.0f : _segs.back()._tend;
}


////////////////////////////////////////////////////////////////////
//     Function: PiecewiseCurve::get_point
//       Access: Published, Virtual
//  Description: Returns the point of the curve at a given parametric
//               point t.  Returns true if t is in the valid range 0.0f
//               <= t <= get_max_t(); if t is outside this range, sets
//               point to the value of the curve at the beginning or
//               end (whichever is nearer) and returns false.
////////////////////////////////////////////////////////////////////
bool PiecewiseCurve::
get_point(float t, LVecBase3f &point) const {
  const ParametricCurve *curve;
  bool result = find_curve(curve, t);

  // We use | instead of || so we won't short-circuit this calculation.
  return result | curve->get_point(t, point);
}


////////////////////////////////////////////////////////////////////
//     Function: PiecewiseCurve::get_tangent
//       Access: Published, Virtual
//  Description: Returns the tangent of the curve at a given parametric
//               point t.
////////////////////////////////////////////////////////////////////
bool PiecewiseCurve::
get_tangent(float t, LVecBase3f &tangent) const {
  const ParametricCurve *curve;
  bool result = find_curve(curve, t);

  // We use | instead of || so we won't short-circuit this calculation.
  return result | curve->get_tangent(t, tangent);
}


////////////////////////////////////////////////////////////////////
//     Function: PiecewiseCurve::get_2ndtangent
//       Access: Published, Virtual
//  Description: Returns the tangent of the first derivative of the
//               curve at the point t.
////////////////////////////////////////////////////////////////////
bool PiecewiseCurve::
get_2ndtangent(float t, LVecBase3f &tangent2) const {
  const ParametricCurve *curve;
  bool result = find_curve(curve, t);

  // We use | instead of || so we won't short-circuit this calculation.
  return result | curve->get_2ndtangent(t, tangent2);
}

////////////////////////////////////////////////////////////////////
//     Function: PiecewiseCurve::adjust_point
//       Access: Published, Virtual
//  Description: Recomputes the curve such that it passes through the
//               point (px, py, pz) at time t, but keeps the same
//               tangent value at that point.
////////////////////////////////////////////////////////////////////
bool PiecewiseCurve::
adjust_point(float t,
             float px, float py, float pz) {
  if (parametrics_cat.is_debug()) {
    parametrics_cat.debug()
      << "Adjusting point at " << t << " to " << px << " " << py << " "
      << pz << "\n";
  }

  const ParametricCurve *curve;
  bool result = find_curve(curve, t);

  if (!result) {
    cerr << "No curve segment at t = " << t << "\n";
    return false;
  }

  rebuild_curveseg(RT_CV | RT_KEEP_ORIG, 0.0f, LVecBase4f(),
                   RT_POINT, t, LVecBase4f(px, py, pz, 1.0f),
                   RT_TANGENT | RT_KEEP_ORIG, t, LVecBase4f(),
                   RT_CV | RT_KEEP_ORIG, 0.0f, LVecBase4f());
  return true;
}

////////////////////////////////////////////////////////////////////
//     Function: PiecewiseCurve::adjust_tangent
//       Access: Published, Virtual
//  Description: Recomputes the curve such that it has the tangent
//               (tx, ty, tz) at time t, but keeps the same position
//               at the point.
////////////////////////////////////////////////////////////////////
bool PiecewiseCurve::
adjust_tangent(float t,
               float tx, float ty, float tz) {
  const ParametricCurve *curve;
  bool result = find_curve(curve, t);

  if (!result) {
    cerr << "No curve segment at t = " << t << "\n";
    return false;
  }

  rebuild_curveseg(RT_CV | RT_KEEP_ORIG, 0.0f, LVecBase4f(),
                   RT_POINT | RT_KEEP_ORIG, t, LVecBase4f(),
                   RT_TANGENT, t, LVecBase4f(tx, ty, tz, 0.0f),
                   RT_CV | RT_KEEP_ORIG, 0.0f, LVecBase4f());
  return true;
}

////////////////////////////////////////////////////////////////////
//     Function: PiecewiseCurve::adjust_pt
//       Access: Published, Virtual
//  Description: Recomputes the curve such that it passes through the
//               point (px, py, pz) with the tangent (tx, ty, tz).
////////////////////////////////////////////////////////////////////
bool PiecewiseCurve::
adjust_pt(float t,
          float px, float py, float pz,
          float tx, float ty, float tz) {
  const ParametricCurve *curve;
  bool result = find_curve(curve, t);

  if (!result) {
    cerr << "No curve segment at t = " << t << "\n";
    return false;
  }

  rebuild_curveseg(RT_CV | RT_KEEP_ORIG, 0.0f, LVecBase4f(),
                   RT_POINT, t, LVecBase4f(px, py, pz, 1.0f),
                   RT_TANGENT, t, LVecBase4f(tx, ty, tz, 0.0f),
                   RT_CV | RT_KEEP_ORIG, 0.0f, LVecBase4f());
  return true;
}


////////////////////////////////////////////////////////////////////
//     Function: PiecewiseCurve::get_pt
//       Access: Published, Virtual
//  Description: Simultaneously returns the point and tangent of the
//               curve at a given parametric point t.
////////////////////////////////////////////////////////////////////
bool PiecewiseCurve::
get_pt(float t, LVecBase3f &point, LVecBase3f &tangent) const {
  const ParametricCurve *curve;
  bool result = find_curve(curve, t);

  // We use | instead of || so we won't short-circuit this calculation.
  return result | curve->get_pt(t, point, tangent);
}


////////////////////////////////////////////////////////////////////
//     Function: PiecewiseCurve::get_num_segs
//       Access: Public
//  Description: Returns the number of curve segments that make up the
//               Piecewise curve.
////////////////////////////////////////////////////////////////////
int PiecewiseCurve::
get_num_segs() const {
  return _segs.size();
}

////////////////////////////////////////////////////////////////////
//     Function: PiecewiseCurve::get_curveseg
//       Access: Public
//  Description: Returns the curve segment corresponding to the given
//               index.
////////////////////////////////////////////////////////////////////
ParametricCurve *PiecewiseCurve::
get_curveseg(int ti) {
  assert(ti >= 0 && ti < (int)_segs.size());
  return _segs[ti]._curve;
}


////////////////////////////////////////////////////////////////////
//     Function: PiecewiseCurve::insert_curveseg
//       Access: Public
//  Description: Inserts a new curve segment at the indicated index.
//               The curve segment must have been allocated via
//               new; it will be freed using delete when it is removed
//               or the PiecewiseCurve destructs.
//
//               If the curve segment is not inserted at the end, its
//               tlength is subtracted from that of the following
//               segment, so that the overall length of the curve is
//               not changed.
////////////////////////////////////////////////////////////////////
bool PiecewiseCurve::
insert_curveseg(int ti, ParametricCurve *seg, float tlength) {
  if (ti < 0 || ti > (int)_segs.size()) {
    return false;
  }

  if (ti == (int)_segs.size()) {
    _segs.push_back(Curveseg(seg, get_max_t() + tlength));

  } else if (ti==0) {
    _segs.insert(_segs.begin(),
                 Curveseg(seg, tlength));

  } else {
    _segs.insert(_segs.begin() + ti,
                 Curveseg(seg, _segs[ti-1]._tend + tlength));
  }

  return true;
}


////////////////////////////////////////////////////////////////////
//     Function: PiecewiseCurve::remove_curveseg
//       Access: Public
//  Description: Removes the given curve segment from the curve and
//               frees it.  Returns true if the segment was defined,
//               false otherwise.
////////////////////////////////////////////////////////////////////
bool PiecewiseCurve::
remove_curveseg(int ti) {
  if (ti < 0 || ti >= (int)_segs.size()) {
    return false;
  }

  float tlength = get_tlength(ti);
  _segs.erase(_segs.begin() + ti);

  // Now update the _tend figures for everything after the one we
  // removed.
  while (ti < (int)_segs.size()) {
    _segs[ti]._tend -= tlength;
    ti++;
  }

  _last_ti = 0;
  return true;
}

////////////////////////////////////////////////////////////////////
//     Function: PiecewiseCurve::remove_all_curvesegs
//       Access: Public
//  Description: Removes all curve segments from the curve.
////////////////////////////////////////////////////////////////////
void PiecewiseCurve::
remove_all_curvesegs() {
  _segs.erase(_segs.begin(), _segs.end());
  _last_ti = 0;
}

////////////////////////////////////////////////////////////////////
//     Function: PiecewiseCurve::get_tlength
//       Access: Public
//  Description: Returns the parametric length of the given segment of
//               the curve.
////////////////////////////////////////////////////////////////////
float PiecewiseCurve::
get_tlength(int ti) const {
  assert(ti >= 0 && ti < (int)_segs.size());
  return (ti==0) ? _segs[ti]._tend : _segs[ti]._tend - _segs[ti-1]._tend;
}

////////////////////////////////////////////////////////////////////
//     Function: PiecewiseCurve::get_tstart
//       Access: Public
//  Description: Returns the parametric start of the given segment of
//               the curve.
////////////////////////////////////////////////////////////////////
float PiecewiseCurve::
get_tstart(int ti) const {
  assert(ti >= 0 && ti <= (int)_segs.size());
  return (ti==0) ? 0.0f : _segs[ti-1]._tend;
}

////////////////////////////////////////////////////////////////////
//     Function: PiecewiseCurve::get_tend
//       Access: Public
//  Description: Returns the parametric end of the given segment of
//               the curve.
////////////////////////////////////////////////////////////////////
float PiecewiseCurve::
get_tend(int ti) const {
  assert(ti >= 0 && ti < (int)_segs.size());
  return _segs[ti]._tend;
}


////////////////////////////////////////////////////////////////////
//     Function: PiecewiseCurve::set_tlength
//       Access: Public
//  Description: Sets the parametric length of the given segment of
//               the curve.  The length of the following segment is
//               lengthened by the corresponding amount to keep the
//               overall length of the curve the same.
////////////////////////////////////////////////////////////////////
bool PiecewiseCurve::
set_tlength(int ti, float tlength) {
  if (ti < 0 || ti >= (int)_segs.size()) {
    return false;
  }

  _segs[ti]._tend += tlength - get_tlength(ti);
  return true;
}



////////////////////////////////////////////////////////////////////
//     Function: PiecewiseCurve::make_nurbs
//       Access: Public
//  Description: Defines the curve as a general NURBS curve.  The
//               order is the degree plus one and must be 1, 2, 3, or
//               4; cvs is an array of num_cvs points each with a
//               homogeneous coordinate; knots is an array of
//               num_cvs+order knot values.
//
//               This creates the individual curve segments and sets
//               up the basis matrices, but does not store the CV's or
//               knot values so the curve shape is not later
//               modifiable.
////////////////////////////////////////////////////////////////////
void PiecewiseCurve::
make_nurbs(int order, int num_cvs,
           const float knots[], const LVecBase4f cvs[]) {
  remove_all_curvesegs();

  for (int i=0; i<num_cvs - order + 1; i++) {
    if (knots[i+order] > knots[i+order-1]) {
      int ti = get_num_segs();
      bool result =
        insert_curveseg(ti, new CubicCurveseg(order, knots+i, cvs+i),
                        knots[i+order] - knots[i+order-1]);
      assert(result);
    }
  }
}


////////////////////////////////////////////////////////////////////
//     Function: PiecewiseCurve::get_bezier_segs
//       Access: Public, Virtual
//  Description: Fills up the indicated vector with a list of
//               BezierSeg structs that describe the curve.  This
//               assumes the curve is a PiecewiseCurve of
//               CubicCurvesegs.  Returns true if successful, false
//               otherwise.
////////////////////////////////////////////////////////////////////
bool PiecewiseCurve::
get_bezier_segs(BezierSegs &bz_segs) const {
  bz_segs.erase(bz_segs.begin(), bz_segs.end());
  int i;
  BezierSeg seg;
  for (i = 0; i < (int)_segs.size(); i++) {
    if (!_segs[i]._curve->get_bezier_seg(seg)) {
      return false;
    }
    seg._t = _segs[i]._tend;
    bz_segs.push_back(seg);
  }

  return true;
}

////////////////////////////////////////////////////////////////////
//     Function: PiecewiseCurve::rebuild_curveseg
//       Access: Public, Virtual
//  Description: Rebuilds the current curve segment (as selected by
//               the most recent call to find_curve()) according to
//               the specified properties (see
//               CubicCurveseg::compute_seg).  Returns true if
//               possible, false if something goes horribly wrong.
////////////////////////////////////////////////////////////////////
bool PiecewiseCurve::
rebuild_curveseg(int, float, const LVecBase4f &,
                 int, float, const LVecBase4f &,
                 int, float, const LVecBase4f &,
                 int, float, const LVecBase4f &) {
  cerr << "rebuild_curveseg not implemented for this curve type.\n";
  return false;
}

////////////////////////////////////////////////////////////////////
//     Function: PiecewiseCurve::find_curve
//       Access: Protected
//  Description: Finds the curve corresponding to the given value of
//               t.  If t is inside the curve's defined range, sets
//               curve to the appropriate segment, translates t to
//               [0,1] to index into the segment's coordinate system,
//               and returns true.  If t is outside the curve's
//               defined range, sets curve to the nearest segment and
//               t to the nearest point on this segment, and returns
//               false.
////////////////////////////////////////////////////////////////////
bool PiecewiseCurve::
find_curve(const ParametricCurve *&curve, float &t) const {
  // Check the index computed by the last call to find_curve().  If
  // it's still a reasonable starting value, start searching from
  // there.  This way, we take advantage of locality of reference: the
  // search is trivial it is the same segment as last time, or the
  // next segment after the last one.
  if (_last_ti>0 && _segs[_last_ti-1]._tend>=t) {
    // However, if the new t value precedes that of last time, we'll
    // have to start over.

    // We do some messy casting so we can get away with assigning a
    // value to a member within a const function.  This assignment
    // doesn't really count as a const violation since we're just
    // updating a cached value, not changing any real data of the
    // class.
    ((PiecewiseCurve *)this)->_last_ti = 0;
  }

  int ti;
  for (ti = _last_ti; ti < (int)_segs.size(); ti++) {
    if (_segs[ti]._tend+0.00001f > t) {
      break;
    }
  }

  if (ti < (int)_segs.size()) {
    // Adjust t to the range [0,1).
    if (ti > 0) {
      t = (t - _segs[ti-1]._tend) / (_segs[ti]._tend - _segs[ti-1]._tend);
    } else {
      t /= _segs[0]._tend;
    }
  }

  if (t < 0) {
    // Oops.
    curve = _segs[0]._curve;
    t = 0.0f;
    return false;
  }

  if (ti >= (int)_segs.size() || !_segs[ti]._curve->is_valid()) {
    assert(ti <= (int)_segs.size());

    // If we're out of bounds, or the curve is undefined, we're probably
    // screwed.  There's one exception: if we were right on a border between
    // curves, try the curve before.

    if (ti > 0 && t < _segs[ti-1]._tend+0.0001f) {
      ti--;
      t = 1.0f;
    }

    if (ti >= (int)_segs.size()) {
      if (_segs.empty()) {
        curve = NULL;
        t = 0.0f;
        return false;
      } else {
        curve = _segs.back()._curve;
        t = 1.0f;
        return false;
      }
    } else if (!_segs[ti]._curve->is_valid()) {
      curve = _segs[ti]._curve;
      return false;
    }
  }

  // Again, some messy casting so we can get away with updating the
  // cached index value for next time.
  ((PiecewiseCurve *)this)->_last_ti = ti;

  // Now scale t back into the curve's own valid range.
  t *= _segs[ti]._curve->get_max_t();
  curve = _segs[ti]._curve;
  return true;
}


////////////////////////////////////////////////////////////////////
//     Function: PiecewiseCurve::current_seg_range
//       Access: Protected
//  Description: Returns a number in the range [0,1], representing the
//               conversion of t into the current segment's coordinate
//               system (the segment last returned by find_curve).
//               This operation is already performed automatically on
//               the t passed into find_seg; this function is useful
//               only to adjust a different value into the same range.
//
//               It is an error to call this function if find_curve()
//               has not yet been called, or if find_curve() returned
//               false from its previous call.
////////////////////////////////////////////////////////////////////
float PiecewiseCurve::
current_seg_range(float t) const {
  int ti = _last_ti;

  assert(ti < (int)_segs.size());

  // Adjust t to the range [0,1).
  if (ti > 0) {
    t = (t - _segs[ti-1]._tend) / (_segs[ti]._tend - _segs[ti-1]._tend);
  } else {
    t /= _segs[0]._tend;
  }

  return t;
}

////////////////////////////////////////////////////////////////////
//     Function: PiecewiseCurve::write_datagram
//       Access: Protected, Virtual
//  Description: Function to write the important information in
//               the particular object to a Datagram
////////////////////////////////////////////////////////////////////
void PiecewiseCurve::
write_datagram(BamWriter *manager, Datagram &me) {
  ParametricCurve::write_datagram(manager, me);

  me.add_uint32(_segs.size());
  size_t i;
  for (i = 0; i < _segs.size(); i++) {
    const Curveseg &seg = _segs[i];
    manager->write_pointer(me, seg._curve);
    me.add_float64(seg._tend);
  }

  _last_ti = 0;
}

////////////////////////////////////////////////////////////////////
//     Function: PiecewiseCurve::fillin
//       Access: Protected
//  Description: Function that reads out of the datagram (or asks
//               manager to read) all of the data that is needed to
//               re-create this object and stores it in the appropiate
//               place
////////////////////////////////////////////////////////////////////
void PiecewiseCurve::
fillin(DatagramIterator &scan, BamReader *manager) {
  ParametricCurve::fillin(scan, manager);

  size_t num_segs = scan.get_uint32();
  _segs.reserve(num_segs);
  size_t i;
  for (i = 0; i < num_segs; i++) {
    Curveseg seg;
    manager->read_pointer(scan);
    seg._curve = (ParametricCurve *)NULL;
    seg._tend = scan.get_float64();
    _segs.push_back(seg);
  }
}

////////////////////////////////////////////////////////////////////
//     Function: PiecewiseCurve::complete_pointers
//       Access: Protected, Virtual
//  Description: Takes in a vector of pointes to TypedWritable
//               objects that correspond to all the requests for
//               pointers that this object made to BamReader.
////////////////////////////////////////////////////////////////////
int PiecewiseCurve::
complete_pointers(TypedWritable **p_list, BamReader *manager) {
  int used = ParametricCurve::complete_pointers(p_list, manager);

  size_t i;
  for (i = 0; i < _segs.size(); i++) {
    _segs[i]._curve = DCAST(ParametricCurve, p_list[used + i]);
  }

  return used + _segs.size();
}
