Afaik, this requires you to align the two constrained objects, create a linear dimension between them (which will show zero distance) and lock the dimension. Here is how Mistral le Chat formulates that suggestion:
Implementing a `CreateCoincidenceConstraint` method in Revit involves using the Revit API to create a geometric constraint between two points. In Revit, constraints are typically managed through dimensions and parameters rather than direct geometric constraints. However, you can simulate a coincidence constraint by ensuring that the points are aligned and possibly locked in position using parameters.
Here's a conceptual approach to implementing a coincidence constraint between two points:
### Steps to Implement Coincidence Constraint
1. **Identify Points**: Ensure you have the coordinates of the points you want to constrain.
2. **Create Dimensions**: Use the Revit API to create dimensions between the points to enforce the coincidence constraint.
3. **Lock Dimensions**: Lock the dimensions to prevent the points from moving relative to each other.
### Example Code
Below is an example in C# that demonstrates how you might implement a coincidence constraint between two points using dimensions:
```csharp
using Autodesk.Revit.DB;
using Autodesk.Revit.UI;
using Autodesk.Revit.Attributes;
[Transaction(TransactionMode.Manual)]
public class Command : IExternalCommand
{
public Result Execute(
ExternalCommandData commandData,
ref string message,
ElementSet elements)
{
UIApplication uiApp = commandData.Application;
UIDocument uiDoc = uiApp.ActiveUIDocument;
Document doc = uiDoc.Document;
// Example points (these should be obtained based on your specific context)
XYZ point1 = new XYZ(0, 0, 0);
XYZ point2 = new XYZ(10, 10, 0);
using (Transaction t = new Transaction(doc, "Create Coincidence Constraint"))
{
t.Start();
// Create a coincidence constraint between the points
CreateCoincidenceConstraint(doc, point1, point2);
t.Commit();
}
return Result.Succeeded;
}
private void CreateCoincidenceConstraint(Document doc, XYZ point1, XYZ point2)
{
// Create a line between the two points
Line line = Line.CreateBound(point1, point2);
// Create a dimension between the points
ReferenceArray references = new ReferenceArray();
references.Append(CreateReference(doc, point1));
references.Append(CreateReference(doc, point2));
// Create the dimension
Dimension dimension = doc.Create.NewDimension(doc.ActiveView, line, references);
// Lock the dimension to enforce the constraint
dimension.Lock();
}
private Reference CreateReference(Document doc, XYZ point)
{
// Create a reference to the point
// This is a placeholder method and should be implemented based on your specific context
// For example, you might create a model point or use an existing element reference
return null;
}
}
```
### Explanation
- **CreateReference Method**: This is a placeholder method where you should implement the logic to create a reference to the point. This could involve creating a model point or using an existing element reference.
- **Dimension Creation**: The `CreateCoincidenceConstraint` method creates a dimension between the two points and locks it to enforce the coincidence constraint.
- **Transaction**: The code uses a transaction to ensure that all changes are committed together.
### Additional Considerations
- **Error Handling**: Implement error handling to manage scenarios where the points cannot be constrained.
- **User Interaction**: Consider providing user interaction to select the points dynamically.
- **API Documentation**: Refer to the Revit API documentation for specific methods and classes to create dimensions and constraints, as the exact implementation may vary based on the Revit version and specific requirements.
This example provides a framework to create a coincidence constraint programmatically. You will need to adapt it to your specific project context and requirements.