Programmatically Creating CAD Files

Question

I need to programmatically create a CAD model. Meaning: The user sets parameters for the model and the application outputs a (insert extension here) file to use in SolidWorks / 3DStudio / Sketchup.

The application generates shells (a tube, for example) with changing radiuses and I would like visualize the shells generated externally, usually in SolidWorks. I suppose it's something like the output of this robot.

I'm not completely sure about the output I need, I need to test a few options. So I'm looking for the technical solution. A good output file to start with will be a tube with a constant external radius, but the internal radius changes with Z (or the other way around).

In SolidWorks, I'd create a spline and use 'Revolved Boss' to extrude it to a shape. Then create another spline and use 'Revolved Cut' to remove the center, like in this picture (Red - the outline of the pipe - the outer radius. Green - The outline of the inner radius): Pipe

(This example is on a tube but the shapes (the intersections) are not really limited, they always consist of geometrical shapes though)

So, my questions are:

Is there an (free if possible) infrastructure to do exactly that? Revloved boss and Revolved Cut?
Does this infrastructure has an option to export to CAD files?
I think I'm using solid modelling - am I?
Should I just create a points cloud (model many intersections and join them together)? Which file format should I use then?

The main use will be for working with solidworks. I'm using C#, but anything goes.

I'm sorry for the vague question - I'm pretty new in CADing from code.

There are surface models, like STL, OBJ, SLP files and then there are solid models like STP, X_T, SAT. There is also the very common standard IGS which is between solids and surfaces. First decide what format you want to target (based on what solidworks likes best) and then see if there are any free or commercial libraries (.dll) out there to handle these files programmatically. I wrote a OBJ file reader recently based on pascal code found in http://home.global.co.za/~jhorn. — John Alexiou, Nov 13 '14 at 18:07
I've edited the question to be more specific. Thanks for the push in the right direction — Nitay, Nov 14 '14 at 14:05

score 4 · Accepted Answer · answered Nov 16 '14 at 19:04

I ended up using Eyeshot SDK. The alternatives I tried:

OpenSCAD - Good, but I was looking for something that integrates with the code, and not as an external application
OpenCASCADE - It seems it can do anything, but it took me too much time to install and configure. Too messy in my opinion

Eyeshot has a pretty simple SDK that is usable straight from C#. The documentation is awful, and I spent way too much time trying to figure out the exception it threw - But it has good code samples. And it's okay once you get to know it. A tad expensive though.

I'm still working on the SolidWorks export. Eyeshot supports STL, IGEN, OBJ, and STEP - Solidworks handles them all okay, but the surfaces are not smooth (circles are not circles just many polygons). As I said - still at work.

Anyway, for future references - Here is some code samples that create something similar (outer radius is constant, inner radius changing) to what I described in the question (Check out one of the samples, like Lego, for how to use WorkUnit):

public class CBuildOutput : WorkUnit
{
    EntityList entities = new EntityList();

    private void CreatePipe()
    {
        double outerRadius = 60;

        // First decide on accuracy
        double chordalError = 0.05;
        int slices = Utility.NumberOfSegments(outerRadius, chordalError);

        // Make a cylinder, the cut a hole from it

        // 1. Cylinder
        Solid cyl = Solid.CreateCylinder(outerRadius, 50, slices);

        // 2. Define the hole curve
        Curve innerCurve = new Curve(2, new List<Point3D>() {
            new Point3D(outerRadius - 20, 0, 0),
            new Point3D(outerRadius - 25, 0, 10),
            new Point3D(outerRadius - 15, 0, 20),
            new Point3D(outerRadius - 25, 0, 30),
            new Point3D(outerRadius - 15, 0, 40),
            new Point3D(outerRadius - 20, 0, 50)});

        // 3. Create an extrude-able sketch
        CompositeCurve holeSketch = new CompositeCurve(
            new Line(Point3D.Origin, new Point3D(40, 0, 0)),
            innerCurve,
            new Line(40, 0, 50, 0, 0, 50));

        // 4. Create a hole solid
        Solid hole = Solid.Revolve(holeSketch, chordalError, 0, 2 * Math.PI, Vector3D.AxisZ, Point3D.Origin, slices, true);

        // 5. Cut the hole from the cylinder    
        Solid[] final = Solid.Difference<Solid>(cyl, hole);

//          entities.Add(cyl, 0, Color.Red);
//          entities.Add(hole, 0, Color.Red);
        entities.Add(final[0], 0, Color.Red);
    }

    protected override void DoWork(System.ComponentModel.BackgroundWorker worker, System.ComponentModel.DoWorkEventArgs doWorkEventArgs)
    {
        CreatePipe();
    }

    protected override void WorkCompleted(ViewportLayout viewportLayout)
    {
        viewportLayout.Entities = entities;
        viewportLayout.ZoomFit();
//          viewportLayout.WriteIGES("model.iges", false);
    }
}

Programmatically Creating CAD Files

1 Answers1