nurbscurve.cpp

/* Mondschein Engine is a fast, powerful, and easy-to-use 3D realtime rendering engine.
 *
 * Copyright (C) 2009-2013 by Andreas Amereller
 * E-Mail: andreas.amereller.dev@googlemail.com
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 3 of the License, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include "core/nurbscurve.h"
//#include <algorithm>

using namespace mondschein;
using namespace math;

void NURBScurve::uniform_knots()
{
  try
  {
    knots.clear();
    if (points.size()<=degree) return;
    knots.assign(points.size()+degree+1,0.0);
    float64 k=knots.size()-degree-1;

    // Set the knot values in uniform length
    for (uint32 i=degree; i<k; ++i)
    {
      knots.at(i)=(i-degree)/(k-degree);
    }
    for (uint32 i=k; i<knots.size(); ++i)
    {
      knots.at(i)=1.0;
    }
    return;
  }
  catch (std::exception &e)
  {
    std::string err("Mondschein Engine ERROR: ");
    err+=e.what();
    err+=", exception raised in function\n\t";
    err+="void mondschein::math::NURBScurve::uniform_knots()";
    throw boost::enable_current_exception(exception()) << exception_error(err);
  }
}

void NURBScurve::chord_knots()
{
  try
  {
    knots.clear();
    if (points.size()<=degree) return;
    knots.assign(points.size()+degree+1,0.0);
    float64 k=knots.size()-degree-1;

    // Calculate the control point distances
    std::vector<float64> distances(1,0.0);
    for (uint32 i=1; i<points.size(); ++i)
    {
      distances.push_back(distances.at(i-1)+(points.at(i)-points.at(i-1)).norm());
    }

    // Create knot values in chord length
    for (uint32 i=degree; i<k; ++i)
    {
      knots.at(i)=distances.at(i-degree)/distances.back();
    }
    for (uint32 i=k; i<knots.size(); ++i)
    {
      knots.at(i)=1.0;
    }
    return;
  }
  catch (std::exception &e)
  {
    std::string err("Mondschein Engine ERROR: ");
    err+=e.what();
    err+=", exception raised in function\n\t";
    err+="void mondschein::math::NURBScurve::chord_knots()";
    throw boost::enable_current_exception(exception()) << exception_error(err);
  }
}

NURBScurve::NURBScurve() : degree(1), points(), knots()
{
  return;
}

NURBScurve::NURBScurve(uint32 _d,const std::vector<Eigen::Vector4d> &_p) : degree(_d), points(_p), knots()
{
  return;
}

NURBScurve::NURBScurve(NURBScurve_c _c) : degree(_c->degree), points(_c->points), knots(_c->knots)
{
  return;
}

NURBScurve::~NURBScurve()
{
  return;
}

NURBScurve &NURBScurve::operator=(NURBScurve_c _c)
{
  degree=_c->degree;
  points=_c->points;
  knots=_c->knots;
  return *this;
}

Eigen::Vector3d NURBScurve::operator()(float64 _t) const
{
  try
  {
    return get_point(_t);
  }
  catch (exception &e)
  {
    std::string err(*boost::get_error_info<exception_error>(e));
    err+=", called in function\n\t";
    err+="Eigen::Vector4d mondschein::math::NURBScurve::operator()(float64 _t) const";
    throw boost::enable_current_exception(e) << exception_error(err);
  }
}

void NURBScurve::set_degree(uint32 _d)
{
  if (_d==0) _d=1;
  degree=_d;
  return;
}

uint32 NURBScurve::get_degree() const
{
  return degree;
}

void NURBScurve::set_points(const std::vector<Eigen::Vector4d> &_p)
{
  points=_p;
  return;
}

std::vector<Eigen::Vector4d> NURBScurve::get_points() const
{
  return points;
}

void NURBScurve::calc_knots(bool _cl)
{
  try
  {
    if (_cl) chord_knots();
    else uniform_knots();
    return;
  }
  catch (exception &e)
  {
    std::string err(*boost::get_error_info<exception_error>(e));
    err+=", called in function\n\t";
    err+="void mondschein::math::NURBScurve::calc_knots(bool _cl) const";
    throw boost::enable_current_exception(e) << exception_error(err);
  }
}

Eigen::Vector3d NURBScurve::get_point(float64 _t) const
{
  if (knots.empty())
  {
    std::string err("Mondschein Engine ERROR: Knot vector must not be empty. ");
    err+="Exception raised in function\n\t";
    err+="Eigen::Vector3d mondschein::math::NURBScurve::get_point(mondschein::float64 _t) const";
    throw boost::enable_current_exception(exception()) << exception_error(err);
  }
  try
  {
    // Clamp _t
    if (_t<=0) return Eigen::Vector3d(points.front()(0),points.front()(1),points.front()(2));
    else if (_t>=1.0) return Eigen::Vector3d(points.back()(0),points.back()(1),points.back()(2));

    // Find the interval
    uint32 i = distance(knots.begin(),upper_bound(knots.begin(),knots.end(),_t))-1;

    // Create the deBoor vector of the needed control points
    std::vector<Eigen::Vector3d> v(degree+1,Eigen::Vector3d(0,0,0));
    Eigen::Vector4d tmp;
    for (uint32 j=i-degree; j<=i; ++j)
    {
      tmp=points.at(j);
      v.at(j-(i-degree)) << tmp(0),tmp(1),tmp(2);
      v.at(j-(i-degree))*=tmp(3);
    }

    // Calculate the curve point by performing the deBoor iterations
    for (uint32 r=1; r<=degree; ++r)
    {
      for (uint32 j=i; j>=i-(degree-r); --j)
      {
        uint32 m=j-i+degree;
        float64 c=(_t-knots.at(j)/(knots.at(j+degree-r+1) - knots.at(j)));
        v.at(m)=(1-c)*v.at(m-1)+c*v.at(m);
      }
    }
    return v.back();
  }
  catch (std::exception &e)
  {
    std::string err("Mondschein Engine ERROR: ");
    err+=e.what();
    err+=", exception raised in function\n\t";
    err+="void mondschein::math::NURBScurve::get_curve_point(float64 _t)";
    throw boost::enable_current_exception(exception()) << exception_error(err);
  }
}