Scripting (.csx models)

C# is EngrCAD’s SCAD language — a model is code either way. The .csx route drops the project file: one script, run through tools/EngrCAD.Script, with the same live loop the compiled workflow gets from dotnet watch:

dotnet run --project tools/EngrCAD.Script -- samples/scripts/bracket.csx              # live window
dotnet run --project tools/EngrCAD.Script -- samples/scripts/bracket.csx --view       # static window
dotnet run --project tools/EngrCAD.Script -- samples/scripts/bracket.csx --export bracket.step
dotnet run --project tools/EngrCAD.Script -- samples/scripts/bracket.csx --render bracket.png

In the live window, saving the .csx re-runs it and swaps the scene in place — camera preserved, a script error keeps the last good scene and shows in the overlay (the runner watches the file and drives the viewer’s own hot-reload path, so the behavior is identical to a dotnet watch edit). --export and --render take every argument EngrCad.Run takes (--render-style, --section, STL/OBJ/STEP by extension).

The script contract is one line: define Scene scene = ...; (or end with a Scene expression). It is the same contract as this documentation’s own executable snippets, compiled through the same Roslyn scripting seam with the same namespaces imported — a fence that works on this site works as a script verbatim, and vice versa.

// bracket.csx — parameters at the top, save the file and the window follows.
double width = 64, depth = 42, thickness = 8;

Shape BossedPlate(double w, double d, double t, double bossD)
{
    var plate = Shape.Extrude(Sketch.RoundedRectangle(w, d, 6), t);
    var boss = Shape.Cylinder(bossD / 2, 1.5 * t).Translate(0, 0, 1.25 * t);
    return plate | boss;   // boss overlaps INTO the plate: transverse, never coplanar
}

var scene = new Scene();
scene.Add(new Part("bracket", BossedPlate(width, depth, thickness, 18), Palette.Steel));

The full version of this script lives at samples/scripts/bracket.csx.

Reusable parametric components are plain C# methods

There is no special “module” construct and none is needed: a reusable parametric component is a method that takes parameters and returns a Shape (or a Part) — BossedPlate above. That is the whole pattern, and it is deliberately the same in every tier of the toolchain:

• in a .csx script, define the method in the script (or #load a shared .csx of your components);
• in a compiled model program, put your component methods in a class library, reference it from any design, and get refactoring, tests and NuGet packaging for free — this is where the .csx route hands over to the live-modeling loop (EngrCad.Run + dotnet watch), which is the same experience with a project file;
• for components that must regenerate, cache, suppress and serialize inside a design, wrap the method in a Feature — and for hardware that also prepares its host, a HardwareComponent.

// The component-method pattern, as this page's own executable example: one method,
// three differently-sized instances.
Shape Spacer(double outerD, double boreD, double height) =>
    Shape.Cylinder(outerD / 2, height)
        .Drill(HoleSpec.Simple(boreD), [new Vector2d(0, 0)], height * 1.05,
               SketchPlane.At((0, 0, height / 2), Vector3d.UnitX, Vector3d.UnitY));

var scene = new Scene();
var tab = scene.AddTab("spacers");
tab.Add(new Part("S", Spacer(12, 5, 6).Translate(-18, 0, 3), Palette.Steel));
tab.Add(new Part("M", Spacer(16, 6, 10).Translate(0, 0, 5), Palette.Brass));
tab.Add(new Part("L", Spacer(22, 8, 16).Translate(22, 0, 8), Palette.Sage));

Run it in your browser

When to choose which

Route	Startup	You get
.csx + EngrCAD.Script	nothing but a text file	the SCAD loop: edit, save, see
console project + EngrCad.Run	dotnet new console + two references	hot reload via dotnet watch, a debugger, tests, NuGet — the product’s core experience

Both run the identical kernel and viewer; the .csx runner is a thin tool (about a hundred lines over the EngrCad.Run front door), not a second product.