Change colour of an edge - c++

Question

I have an graph which consists of edges and vertices. When the clicks an edge in the graph, the edge is supposed to change colour. I have included some code samples to demonstrate my problem.
To draw the initial graph;
#include "StdAfx.h"
#include <vtkSmartPointer.h>
#include <vtkCallbackCommand.h>
#include <vtkAnnotationLink.h>
#include <vtkRenderedGraphRepresentation.h>
#include <vtkRenderer.h>
#include <vtkDoubleArray.h>
#include <vtkSelectionNode.h>
#include <vtkIdTypeArray.h>
#include <vtkSelection.h>
#include <vtkRenderWindow.h>
#include <vtkUnsignedCharArray.h>
#include <vtkObjectFactory.h>
#include <vtkGraphLayoutStrategy.h>
#include <vtkGraphLayoutView.h>
#include <vtkGraphWriter.h>
#include <vtkMutableUndirectedGraph.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkIntArray.h>
#include <vtkLookupTable.h>
#include <vtkDataSetAttributes.h>
#include <vtkViewTheme.h>
void SelectionCallbackFunction(vtkObject* caller, long unsigned int eventId, void* clientData, void* callData);
vtkSmartPointer<vtkMutableUndirectedGraph> g;
int main(int, char *[])
{
g =
vtkSmartPointer<vtkMutableUndirectedGraph>::New();
vtkIdType v1 = g->AddVertex();
vtkIdType v2 = g->AddVertex();
g->AddEdge(v1, v2);
g->AddEdge(v1, v2);
vtkSmartPointer<vtkCallbackCommand> selectionCallback =
vtkSmartPointer<vtkCallbackCommand>::New();
selectionCallback->SetCallback (SelectionCallbackFunction);
// Create the color array
vtkSmartPointer<vtkIntArray> edgeColors =
vtkSmartPointer<vtkIntArray>::New();
edgeColors->SetNumberOfComponents(1);
edgeColors->SetName("Color");
vtkSmartPointer<vtkLookupTable> lookupTable =
vtkSmartPointer<vtkLookupTable>::New();
lookupTable->SetNumberOfTableValues(1);
lookupTable->SetTableValue(0, 1.0, 0.0, 0.0); // red
lookupTable->Build();
edgeColors->InsertNextValue(0);
// Add the color array to the graph
g->GetEdgeData()->AddArray(edgeColors);
vtkSmartPointer<vtkGraphLayoutView> view =
vtkSmartPointer<vtkGraphLayoutView>::New();
view->SetEdgeColorArrayName("Color");
view->ColorEdgesOn();
vtkSmartPointer<vtkViewTheme> theme =
vtkSmartPointer<vtkViewTheme>::New();
theme->SetCellLookupTable(lookupTable);
view->ApplyViewTheme(theme);
view->AddRepresentationFromInput(g);
view->SetLayoutStrategy("Simple 2D");
view->GetRepresentation()->GetAnnotationLink()->AddObserver("AnnotationChangedEvent", selectionCallback);
view->ResetCamera();
view->Render();
view->GetInteractor()->Start();
return EXIT_SUCCESS;
}
For the mouse click function I have used the below code;
vtkAnnotationLink* annotationLink =
static_cast<vtkAnnotationLink*>(caller);
vtkSelection* selection = annotationLink->GetCurrentSelection();
vtkSelectionNode* edges;
if(selection->GetNode(0)->GetFieldType() == vtkSelectionNode::EDGE)
{
edges = selection->GetNode(0);
}
if(selection->GetNode(1)->GetFieldType() == vtkSelectionNode::EDGE)
{
edges = selection->GetNode(1);
}
vtkIdTypeArray* edgeList = vtkIdTypeArray::SafeDownCast(edges->GetSelectionList());
for(vtkIdType i = 0; i < edgeList->GetNumberOfTuples(); i++)
{
//Change colour of the edge
}
My problem is that I cannot change the colour of the edge dynamically. I would be very grateful for any help regarding the matter.

Answer 1

The below code worked for me. First when I create the graph I set the colour of each and every edge,
edgeColors = vtkSmartPointer<vtkIntArray>::New();
edgeColors->SetNumberOfComponents(1);
edgeColors->SetName("Color");
vtkSmartPointer<vtkLookupTable> lookupTable =
vtkSmartPointer<vtkLookupTable>::New();
lookupTable->SetNumberOfTableValues(2);
lookupTable->SetTableValue(0, 0.5, 1.0, 0.5); // green
lookupTable->SetTableValue(1, 0.0, 1.0, 0.0); // white
lookupTable->Build();
//For each edge id insert colour
for(int i = 0;i<=graph->GetNumberOfEdges();i++)
edgeColors->InsertValue(i,0);
// Add the color array to the graph
graph->GetEdgeData()->AddArray(edgeColors);
Then in my mouse click function I get the vtkIdType of the clicked edge and set the colour of it.
vtkIdType edge = edgeList->GetValue(0);
edgeColors->InsertValue(edge.Id,1);//set colour of edge
graphLayoutView->GetInteractor()->Render();