Vehicle routing problem with dependent dimension constraints (Google ORTools) - or-tools

Question

I'm very new to OR-Tools and I'm trying to solve a modified VRP with capacity constraints from Google's guide.
In my problem vehicles transport multiple types of items. Some types can be transported together and others cannot.
What I tried
In the following code the types are A and B (they should not be transported together).
First I defined the two callbacks for demands and added the dimensions to the routing model
int demandACallbackIndex = routing.RegisterUnaryTransitCallback((long fromIndex) => {
var fromNode = manager.IndexToNode(fromIndex);
return demandsA[fromNode];
});
int demandBCallbackIndex = routing.RegisterUnaryTransitCallback((long fromIndex) => {
var fromNode = manager.IndexToNode(fromIndex);
return demandsB[fromNode];
});
routing.AddDimensionWithVehicleCapacity(demandACallbackIndex, 0,
capacitiesA,
true,
"CapacityA");
routing.AddDimensionWithVehicleCapacity(demandBCallbackIndex, 0,
capacitiesB,
true,
"CapacityB");
Then I retrieved the dimensions and added constraints to routing.solver() for every node
var capacityADimension = routing.GetDimensionOrDie("CapacityA");
var capacityBDimension = routing.GetDimensionOrDie("CapacityB");
for (int i = 0; i < noDeliveries; i++) {
var index = manager.NodeToIndex(i);
routing.solver().Add(capacityADimension.CumulVar(index) * capacityBDimension.CumulVar(index) == 0);
}
When I run the solver (with two vehicles) these constraints seem to be ignored (one vehicle remains parked while the other does all the work even though it shouldn't transport both types of items).
Is this even possible with OR-Tools? If yes, what did I do wrong?
Full code
public SimpleVehicleRoutingSolutionDto SolveVehicleRoutingWithItemConstraints(long[,] distances, long[] capacitiesA, long[] capacitiesB, long[] demandsA, long[] demandsB, int depot)
{
int noVehicles = capacitiesA.Length;
int noDeliveries = deliveriesA.Length;
RoutingIndexManager manager =
new RoutingIndexManager(noDeliveries, noVehicles, depot);
RoutingModel routing = new RoutingModel(manager);
int transitCallbackIndex = routing.RegisterTransitCallback((long fromIndex, long toIndex) => {
var fromNode = manager.IndexToNode(fromIndex);
var toNode = manager.IndexToNode(toIndex);
return distances[fromNode, toNode];
});
routing.SetArcCostEvaluatorOfAllVehicles(transitCallbackIndex);
int demandACallbackIndex = routing.RegisterUnaryTransitCallback((long fromIndex) => {
// Convert from routing variable Index to demand NodeIndex.
var fromNode = manager.IndexToNode(fromIndex);
return demandsA[fromNode];
});
int demandBCallbackIndex = routing.RegisterUnaryTransitCallback((long fromIndex) => {
// Convert from routing variable Index to demand NodeIndex.
var fromNode = manager.IndexToNode(fromIndex);
return demandsB[fromNode];
});
routing.AddDimensionWithVehicleCapacity(demandACallbackIndex, 0,
capacitiesA,
true,
"CapacityA");
routing.AddDimensionWithVehicleCapacity(demandBCallbackIndex, 0,
capacitiesB,
true,
"CapacityB");
var capacityADimension = routing.GetDimensionOrDie("CapacityA");
var capacityBDimension = routing.GetDimensionOrDie("CapacityB");
for (int i = 0; i < noDeliveries; i++) {
var index = manager.NodeToIndex(i);
routing.solver().Add(capacityADimension.CumulVar(index) * capacityBDimension.CumulVar(index) == 0);
}
RoutingSearchParameters searchParameters =
operations_research_constraint_solver.DefaultRoutingSearchParameters();
searchParameters.FirstSolutionStrategy = FirstSolutionStrategy.Types.Value.PathCheapestArc;
searchParameters.LocalSearchMetaheuristic = LocalSearchMetaheuristic.Types.Value.GuidedLocalSearch;
searchParameters.TimeLimit = new Duration { Seconds = 1 };
Assignment solution = routing.SolveWithParameters(searchParameters);
var ret = new SimpleVehicleRoutingSolutionDto();
long totalDistance = 0;
for (int i = 0; i < noVehicles; ++i)
{
var vecihle = new VehiclePathDto { Index = i };
long routeDistance = 0;
var index = routing.Start(i);
while (routing.IsEnd(index) == false)
{
long nodeIndex = manager.IndexToNode(index);
vecihle.Waypoints.Add(new WaypointDto { Index = nodeIndex });
var previousIndex = index;
index = solution.Value(routing.NextVar(index));
routeDistance += routing.GetArcCostForVehicle(previousIndex, index, 0);
}
vecihle.Distance = routeDistance;
ret.Vehicles.Add(vecihle);
totalDistance += routeDistance;
}
ret.TotalDistance = totalDistance;
return ret;
}
And the input:
long[,] dist = {
{ 0, 5, 6 },
{ 5, 0, 3 },
{ 6, 3, 0 }
};
long[] capA = { 5, 5 };
long[] capB = { 5, 5 };
long[] demA = { 0, 1, 0 };
long[] demB = { 0, 0, 1 };
var routingSolution = vehicleRouting.SolveVehicleRoutingWithItemConstraints(dist, capA, capB, demA, demB, 0);

Answer 1

I fixed the problem.
The issue was that the number of nodes was 3 (noDeliveries), however the number of indices was 6, so I only set the constraint on half of them.
Fixed code:
for (int i = 0; i < manager.GetNumberOfIndices(); i++) {
routing.solver().Add(capacityADimension.CumulVar(i) * capacityBDimension.CumulVar(i) == 0);
}
EDIT:
Even better if constraints are set only for the route end node, since the CumulVar value is strictly increasing.
for (int j = 0; j < noVehicles; j++) {
var index = routing.End(j);
routing.solver().Add(capacityADimension.CumulVar(index) * capacityBDimension.CumulVar(index) == 0);
}