Featurescript - Creating cylinder in context

Hugh_Goodbody · August 2019

I am writing a featurescript to create a cylinder between two points (usually the centres of two circles). Currently I can create the cylinder between two vertices or mate connectors in a part studio, and this is all good.

I would also like this to work in context but doing it this way, I can only select the edges of circles. I have added the circle selection to the UI:

annotation { "Name" : "Start Point", "Filter" : EntityType.VERTEX || BodyType.MATE_CONNECTOR || (GeometryType.CIRCLE), "MaxNumberOfPicks" : 1 }
definition.startVertex is Query;

So the result of the above is that I either have a vertext point, or a circle.

So my question is: Is the best way to resolve this by incorporating an IF statement, ie IF the user selects a circle, then evaluate the centre point and use this as the vertex? or is there a better way?

The second part to the question, is how do I test if the circle has been selected?

Thanks in advance!

NeilCooke · August 2019

Put evCurveDefinition in a try block to test for a circle (which will fail if it is not a curve)

NeilCooke · August 2019

    precondition
    {
        annotation { "Name" : "Start Point", "Filter" : EntityType.VERTEX || BodyType.MATE_CONNECTOR || (GeometryType.CIRCLE), "MaxNumberOfPicks" : 1 }
        definition.startVertex is Query;
    }
    {
        var startVertex;

        try silent
        {
            startVertex = evCurveDefinition(context, {
                            "edge" : definition.startVertex }).coordSystem.origin;
        }
        catch
        {
            startVertex = evVertexPoint(context, { "vertex" : definition.startVertex });
        }

        println(startVertex);
    });

Jake_Rosenfeld · August 2019

Just to encourage good FS practices, the way we would do this for an official feature is as follows:

precondition
{
    annotation { ... }
    definition.start is Query;
}
{
    // Check if the user has supplied a query, or has left the box blank
    if (size(evaluateQuery(context, definition.start)) != 1)
    {
        // Arguments here are the error that will displayed if the user hovers over the feature, and the name of the 
        // selection box that should be turned red.  Note that it only turns red if a different box is focused; when it
        // is focused, it will always be blue.
        throw regenError("Select start point", ["start"]);
    }

    // Assuming that selecting a point is more common, you would want to check for that first to not waste compute cycles.    
    // The `try silent(...)` and `try(...)` expressions return what is evaluated inside them if there is no error thrown, or
    // return `undefined` if an error is thrown inside them.
    var startPosition = try silent(evVertexPoint(context, { "vertex" : definition.start }));
    if (startPosition == undefined)
    {
        startPosition = try silent(evCurveDefinition(context, { "edge" : definition.start }).coordSystem.origin);
    }
    if (startPosition == undefined)
    {
        // If both checks failed, throw a useful error.  In addition to the parameters described above, I am also passing 
        // definition.start as an error entity. This entity will be highlighted in red to show the user what is wrong.
        throw regenError("Start point should be a vertex, a mate connector, or a circular edge", ["start"], definition.start);
    }
}

Some info on all this try and try silent stuff:
https://cad.onshape.com/FsDoc/exceptions.html

Another tip for this: once you find the two positions that you care about, `fCylinder` is going to be your best friend. It does exactly what you want (take two points and a radius and make a cylinder between them):
https://cad.onshape.com/FsDoc/library.html#fCylinder-Context-Id-map

Hugh_Goodbody · August 2019

Thanks Jake, will endeavour to incorporate!

Featurescript - Creating cylinder in context

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