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vtkArcParallelEdgeStrategy.cxx
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vtkArcParallelEdgeStrategy.cxx
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/*=========================================================================
Program: Visualization Toolkit
Module: vtkArcParallelEdgeStrategy.cxx
Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
All rights reserved.
See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
This software is distributed WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE. See the above copyright notice for more information.
=========================================================================*/
/*----------------------------------------------------------------------------
Copyright (c) Sandia Corporation
See Copyright.txt or http://www.paraview.org/HTML/Copyright.html for details.
----------------------------------------------------------------------------*/
#include "vtkArcParallelEdgeStrategy.h"
#include "vtkCellArray.h"
#include "vtkCommand.h"
#include "vtkDirectedGraph.h"
#include "vtkEdgeListIterator.h"
#include "vtkGraph.h"
#include "vtkMath.h"
#include "vtkObjectFactory.h"
#include "vtkPoints.h"
#include "vtkSmartPointer.h"
#include <utility>
#include <vector>
#include <map>
vtkStandardNewMacro(vtkArcParallelEdgeStrategy);
vtkArcParallelEdgeStrategy::vtkArcParallelEdgeStrategy()
{
this->NumberOfSubdivisions = 10;
}
vtkArcParallelEdgeStrategy::~vtkArcParallelEdgeStrategy()
{
}
void vtkArcParallelEdgeStrategy::Layout()
{
bool directed = vtkDirectedGraph::SafeDownCast(this->Graph) != 0;
std::map<std::pair<vtkIdType, vtkIdType>, int> edgeCount;
std::map<std::pair<vtkIdType, vtkIdType>, int> edgeNumber;
std::vector<vtkEdgeType> edgeVector(this->Graph->GetNumberOfEdges());
vtkSmartPointer<vtkEdgeListIterator> it =
vtkSmartPointer<vtkEdgeListIterator>::New();
this->Graph->GetEdges(it);
double avgEdgeLength = 0.0;
while (it->HasNext())
{
vtkEdgeType e = it->Next();
vtkIdType src, tgt;
if (directed || e.Source < e.Target)
{
src = e.Source;
tgt = e.Target;
}
else
{
src = e.Target;
tgt = e.Source;
}
edgeCount[std::pair<vtkIdType, vtkIdType>(src, tgt)]++;
edgeVector[e.Id] = e;
// Compute edge length
double sourcePt[3];
double targetPt[3];
this->Graph->GetPoint(e.Source, sourcePt);
this->Graph->GetPoint(e.Target, targetPt);
avgEdgeLength +=
sqrt(vtkMath::Distance2BetweenPoints(sourcePt, targetPt));
}
vtkIdType numEdges = this->Graph->GetNumberOfEdges();
if (numEdges > 0)
{
avgEdgeLength /= numEdges;
}
else
{
avgEdgeLength = 1.0;
}
double maxLoopHeight = avgEdgeLength / 10.0;
double* pts = new double[this->NumberOfSubdivisions*3];
for (vtkIdType eid = 0; eid < numEdges; ++eid)
{
vtkEdgeType e = edgeVector[eid];
vtkIdType src, tgt;
if (directed || e.Source < e.Target)
{
src = e.Source;
tgt = e.Target;
}
else
{
src = e.Target;
tgt = e.Source;
}
// Lookup the total number of edges with this source
// and target, as well as how many times this pair
// has been found so far.
std::pair<vtkIdType,vtkIdType> p(src, tgt);
edgeNumber[p]++;
int cur = edgeNumber[p];
int total = edgeCount[p];
std::pair<vtkIdType,vtkIdType> revP(tgt, src);
int revTotal = edgeCount[revP];
double sourcePt[3];
double targetPt[3];
this->Graph->GetPoint(e.Source, sourcePt);
this->Graph->GetPoint(e.Target, targetPt);
// If only one edge between source and target,
// just draw a straight line.
if (total + revTotal == 1)
{
double pt[6];
pt[0] = sourcePt[0];
pt[1] = sourcePt[1];
pt[2] = sourcePt[2];
pt[3] = targetPt[0];
pt[4] = targetPt[1];
pt[5] = targetPt[2];
this->Graph->SetEdgePoints(e.Id, 2, pt);
continue;
}
// Find vector from source to target
double delta[3];
for (int c = 0; c < 3; ++c)
{
delta[c] = targetPt[c] - sourcePt[c];
}
double dist = vtkMath::Norm(delta);
// If the distance is zero, draw a loop.
if (dist == 0)
{
double radius = maxLoopHeight*cur/total;
double u[3] = {1.0, 0.0, 0.0};
double v[3] = {0.0, 1.0, 0.0};
double center[3] = {sourcePt[0] - radius, sourcePt[1], sourcePt[2]};
// Use the general equation for a circle in three dimensions
// to draw a loop.
for (int s = 0; s < this->NumberOfSubdivisions; ++s)
{
double angle = 2.0*vtkMath::Pi()
*s/(this->NumberOfSubdivisions-1);
for (int c = 0; c < 3; ++c)
{
pts[3*s + c] = center[c]
+ radius*cos(angle)*u[c]
+ radius/2.0*sin(angle)*v[c];
}
}
this->Graph->SetEdgePoints(e.Id, this->NumberOfSubdivisions, pts);
continue;
}
// Find vector perpendicular to delta
// and (0,0,1).
double z[3] = {0.0, 0.0, 1.0};
double w[3];
vtkMath::Cross(delta, z, w);
vtkMath::Normalize(w);
// Really bad ascii art:
// ___-------___
// / |height\ <-- the drawn arc
// src----dist-----tgt
// \ | /
// \ |offset
// \ | /
// u \ | / x
// \ | /
// \ | /
// \|/
// center
// The center of the circle used to draw the arc is a
// point along the vector w a certain distance (offset)
// from the midpoint of sourcePt and targetPt.
// The offset is computed to give a certain arc height
// based on cur and total.
double maxHeight = dist/8.0;
double height;
int sign = 1;
if (directed)
{
// Directed edges will go on one side or the other
// automatically based on the order of source and target.
height = (static_cast<double>(cur)/total)*maxHeight;
}
else
{
// For undirected edges, place every other edge on one
// side or the other.
height = (static_cast<double>((cur+1)/2)/(total/2))*maxHeight;
if (cur % 2)
{
sign = -1;
}
}
// This formula computes offset given dist and height.
// You can pull out your trig formulas and verify it :)
double offset = (dist*dist/4.0 - height*height)/(2.0*height);
double center[3];
for (int c = 0; c < 3; ++c)
{
center[c] = (targetPt[c] + sourcePt[c])/2.0 + sign*offset*w[c];
}
// The vectors u and x are unit vectors pointing from the
// center of the circle to the two endpoints of the arc,
// sourcePt and targetPt, respectively.
double u[3], x[3];
for (int c = 0; c < 3; ++c)
{
u[c] = sourcePt[c] - center[c];
x[c] = targetPt[c] - center[c];
}
double radius = vtkMath::Norm(u);
vtkMath::Normalize(u);
vtkMath::Normalize(x);
// Find the angle that the arc spans.
double theta = acos(vtkMath::Dot(u, x));
// We need two perpendicular vectors on the plane of the circle
// in order to draw the circle. First we calculate n, a vector
// normal to the circle, by crossing u and w. Next, we cross
// n and u in order to get a vector v in the plane of the circle
// that is perpendicular to u.
double n[3];
vtkMath::Cross(u, w, n);
vtkMath::Normalize(n);
double v[3];
vtkMath::Cross(n, u, v);
vtkMath::Normalize(v);
// Use the general equation for a circle in three dimensions
// to draw an arc from the last point to the current point.
for (int s = 0; s < this->NumberOfSubdivisions; ++s)
{
double angle = -sign*s*theta/(this->NumberOfSubdivisions - 1.0);
for (int c = 0; c < 3; ++c)
{
pts[3*s + c] = center[c]
+ radius*cos(angle)*u[c]
+ radius*sin(angle)*v[c];
}
}
this->Graph->SetEdgePoints(e.Id, this->NumberOfSubdivisions, pts);
if (eid % 1000 == 0)
{
double progress = eid / static_cast<double>(numEdges);
this->InvokeEvent(vtkCommand::ProgressEvent, static_cast<void*>(&progress));
}
}
double progress = 1.0;
this->InvokeEvent(vtkCommand::ProgressEvent, static_cast<void*>(&progress));
delete [] pts;
}
void vtkArcParallelEdgeStrategy::PrintSelf(ostream& os, vtkIndent indent)
{
this->Superclass::PrintSelf(os,indent);
os << indent << "NumberOfSubdivisions: " << this->NumberOfSubdivisions << endl;
}