cylinder.h 10.2 KB
``````#ifndef STIM_CYLINDER_H
#define STIM_CYLINDER_H
#include <iostream>
#include <stim/math/circle.h>
#include <stim/math/vector.h>

namespace stim
{
template<typename T>
class cylinder
{
private:
stim::circle<T> s;			//an arbitrary circle
std::vector<stim::circle<T> > e;
std::vector<stim::vec<T> > mags;
std::vector< T > L;			//length of the cylinder at each position.

///default init
void
init()
{

}

///inits the cylinder from a list of points (inP) and radii (inM)
void
init(std::vector<stim::vec<T> > inP, std::vector<stim::vec<T> > inM)
{
mags = inM;
stim::vec<float> v1;
stim::vec<float> v2;
e.resize(inP.size());
if(inP.size() < 2)
return;

//calculate each L.
L.resize(inP.size());
T temp = (T)0;
L[0] = 0;
for(int i = 1; i < L.size(); i++)
{
temp += (inP[i-1] - inP[i]).len();
L[i] = temp;
}

stim::vec<T> dr = (inP[1] - inP[0]).norm();
s = stim::circle<T>(inP[0], inM[0][0], dr, stim::vec<T>(1,0,0));
e[0] = s;
for(int i = 1; i < inP.size()-1; i++)
{
s.center(inP[i]);
v1 = (inP[i] - inP[i-1]).norm();
v2 = (inP[i+1] - inP[i]).norm();
dr = (v1+v2).norm();
s.normal(dr);
s.scale(inM[i][0]/inM[i-1][0]);
e[i] = s;
}

int j = inP.size()-1;
s.center(inP[j]);
dr = (inP[j] - inP[j-1]).norm();
s.normal(dr);
s.scale(inM[j][0]/inM[j-1][0]);
e[j] = s;
}

///returns the direction vector at point idx.
stim::vec<T>
d(int idx)
{
if(idx == 0)
{
return (e[idx+1].P - e[idx].P).norm();
}
else if(idx == e.size()-1)
{
return (e[idx].P - e[idx-1].P).norm();
}
else
{
//				return (e[idx+1].P - e[idx].P).norm();
stim::vec<float> v1 = (e[idx].P-e[idx-1].P).norm();
stim::vec<float> v2 = (e[idx+1].P-e[idx].P).norm();
return (v1+v2).norm();
}
//		return e[idx].N;

}

stim::vec<T>
d(T l, int idx)
{
if(idx == 0 || idx == e.size()-1)
{
return e[idx].N;
}
else
{
T rat = (l-L[idx])/(L[idx+1]-L[idx]);
return(	e[idx].N + (e[idx+1].N - e[idx].N)*rat);
}
}

///finds the index of the point closest to the length l on the lower bound.
///binary search.
int
findIdx(T l)
{
unsigned int i = L.size()/2;
unsigned int max = L.size()-1;
unsigned int min = 0;
while(i > 0 && i < L.size()-1)
{
//				std::cerr << "Trying " << i << std::endl;
//				std::cerr << "l is " << l << ", L[" << i << "]" << L[i] << std::endl;
if(l < L[i])
{
max = i;
i = min+(max-min)/2;
}
else if(L[i] <= l && L[i+1] >= l)
{
break;
}
else
{
min = i;
i = min+(max-min)/2;
}
}
return i;
}

public:
///default constructor
cylinder()
{

}

///constructor to create a cylinder from a set of points, radii, and the number of sides for the cylinder.
///@param inP:  Vector of stim vecs composing the points of the centerline.
///@param inM:  Vector of stim vecs composing the radii of the centerline.
cylinder(std::vector<stim::vec<T> > inP, std::vector<stim::vec<T> > inM){
init(inP, inM);
}

///Constructor defines a cylinder with centerline inP and magnitudes of zero
///@param inP: Vector of stim vecs composing the points of the centerline
cylinder(std::vector< stim::vec<T> > inP){
std::vector< stim::vec<T> > inM;						//create an array of arbitrary magnitudes

stim::vec<T> zero;
zero.push_back(0);

inM.resize(inP.size(), zero);								//initialize the magnitude values to zero
init(inP, inM);
}

///Returns the number of points on the cylinder centerline

unsigned int size(){
return e.size();
}

///Returns a position vector at the given p-value (p value ranges from 0 to 1).
///interpolates the position along the line.
///@param pvalue: the location of the in the cylinder, from 0 (beginning to 1).
stim::vec<T>
p(T pvalue)
{
if(pvalue < 0.0 || pvalue > 1.0)
{
return stim::vec<float>(-1,-1,-1);
}
T l = pvalue*L[L.size()-1];
int idx = findIdx(l);
T rat = (l-L[idx])/(L[idx+1]-L[idx]);
return(	e[idx].P + (e[idx+1].P-e[idx].P)*rat);
}

///Returns a position vector at the given length into the fiber (based on the pvalue).
///Interpolates the radius along the line.
///@param l: the location of the in the cylinder.
///@param idx: integer location of the point closest to l but prior to it.
stim::vec<T>
p(T l, int idx)
{
T rat = (l-L[idx])/(L[idx+1]-L[idx]);
return(	e[idx].P + (e[idx+1].P-e[idx].P)*rat);
//			return(
//			return (pos[idx] + (pos[idx+1]-pos[idx])*((l-L[idx])/(L[idx+1]- L[idx])));
}

///Returns a radius at the given p-value (p value ranges from 0 to 1).
///interpolates the radius along the line.
///@param pvalue: the location of the in the cylinder, from 0 (beginning to 1).
T
r(T pvalue)
{
if(pvalue < 0.0 || pvalue > 1.0)
return;
T l = pvalue*L[L.size()-1];
int idx = findIdx(l);
return (e[idx].U.len() + (e[idx+1].U.len() - e[idx].U.len())*((l-L[idx])/(L[idx+1]- L[idx])));
}

///Returns a radius at the given length into the fiber (based on the pvalue).
///Interpolates the position along the line.
///@param l: the location of the in the cylinder.
///@param idx: integer location of the point closest to l but prior to it.
T
r(T l, int idx)
{
T rat = (l-L[idx])/(L[idx+1]-L[idx]);
return(	e[idx].U.len() + (e[idx+1].U.len() - e[idx].U.len())*rat);
}

///	Returns the magnitude at the given index
///	@param i is the index of the desired point
/// @param m is the index of the magnitude value
T ri(unsigned i, unsigned m = 0){
return mags[i][m];
}

/// Adds a new magnitude value to all points
/// @param m is the starting value for the new magnitude
for(unsigned int p = 0; p < e.size(); p++)
mags[p].push_back(m);
}

/// Sets a magnitude value
/// @param val is the new value for the magnitude
/// @param p is the point index for the magnitude to be set
/// @param m is the index for the magnitude
void set_mag(T val, unsigned p, unsigned m = 0){
mags[p][m] = val;
}

/// Returns the number of magnitude values at each point
unsigned nmags(){
return mags[0].size();
}

///returns the position of the point with a given pvalue and theta on the surface
///in x, y, z coordinates. Theta is in degrees from 0 to 360.
///@param pvalue: the location of the in the cylinder, from 0 (beginning to 1).
///@param theta: the angle to the point of a circle.
stim::vec<T>
surf(T pvalue, T theta)
{
if(pvalue < 0.0 || pvalue > 1.0)
{
return stim::vec<float>(-1,-1,-1);
} else {
T l = pvalue*L[L.size()-1];
int idx = findIdx(l);
stim::vec<T> ps = p(l, idx);
T m = r(l, idx);
s = e[idx];
s.center(ps);
s.normal(d(l, idx));
s.scale(m/e[idx].U.len());
return(s.p(theta));
}
}

///returns a vector of points necessary to create a circle at every position in the fiber.
///@param sides: the number of sides of each circle.
std::vector<std::vector<vec<T> > >
getPoints(int sides)
{
std::vector<std::vector <vec<T> > > points;
points.resize(e.size());
for(int i = 0; i < e.size(); i++)
{
points[i] = e[i].getPoints(sides);
}
return points;
}

///returns the total length of the line at index j.
T
getl(int j)
{
return (L[j]);
}
/// Allows a point on the centerline to be accessed using bracket notation

vec<T> operator[](unsigned int i){
return e[i].P;
}

/// Returns the total length of the cylinder centerline
T length(){
return L.back();
}

/// Integrates a magnitude value along the cylinder.
/// @param m is the magnitude value to be integrated (this is usually the radius)
T integrate(unsigned m = 0){

T M = 0;						//initialize the integral to zero
T m0, m1;						//allocate space for both magnitudes in a single segment

//vec<T> p0, p1;					//allocate space for both points in a single segment

m0 = mags[0][m];				//initialize the first point and magnitude to the first point in the cylinder
//p0 = pos[0];

T len = L[0];						//allocate space for the segment length

//for every consecutive point in the cylinder
for(unsigned p = 1; p < e.size(); p++){

//p1 = pos[p];							//get the position and magnitude for the next point
m1 = mags[p][m];

if(p > 1) len = (L[p-1] - L[p-2]);		//calculate the segment length using the L array

//add the average magnitude, weighted by the segment length
M += (m0 + m1)/2.0 * len;

m0 = m1;								//move to the next segment by shifting points
}
return M;			//return the integral
}

/// Averages a magnitude value across the cylinder
/// @param m is the magnitude value to be averaged (this is usually the radius)
T average(unsigned m = 0){

//return the average magnitude
return integrate(m) / L.back();
}

/// Resamples the cylinder to provide a maximum distance of "spacing" between centerline points. All current
///		centerline points are guaranteed to exist in the new cylinder
/// @param spacing is the maximum spacing allowed between sample points
cylinder<T> resample(T spacing){

std::vector< vec<T> > result;

vec<T> p0 = e[0].P;								//initialize p0 to the first point on the centerline
vec<T> p1;
unsigned N = size();							//number of points in the current centerline

//for each line segment on the centerline
for(unsigned int i = 1; i < N; i++){
p1 = e[i].P;								//get the second point in the line segment

vec<T> v = p1 - p0;							//calculate the vector between these two points
T d = v.len();								//calculate the distance between these two points (length of the line segment)

unsigned nsteps = d / spacing+1;		//calculate the number of steps to take along the segment to meet the spacing criteria
T stepsize = 1.0 / nsteps;			//calculate the parametric step size between new centerline points

//for each step along the line segment
for(unsigned s = 0; s < nsteps; s++){
T alpha = stepsize * s;					//calculate the fraction of the distance along the line segment covered
result.push_back(p0 + alpha * v);	//push the point at alpha position along the line segment
}

p0 = p1;								//shift the points to move to the next line segment
}

result.push_back(e[size() - 1].P);			//push the last point in the centerline

return cylinder<T>(result);

}

};

}
#endif
``````