Extending the Sweep built in shapes

Ray.Collett — Fri, 19 Dec 2025 22:44:12 GMT

I'm trying to create a library of Sweep shapes by expanding the built in list, but I'm having problems getting it to work.

First, I created a new shape type using the plugin simpleSpline system. The script file is in my startup folder, and my new shape appears in the modifier panel under Create -> Shape -> RayScripts as expected. I can choose on my new shape and draw it in the viewport. I have a parameters panel exposed, and adjusting the values causes the shape to redraw properly.

Secondly, I modified the \plugcfg\sweep.ini file to add my custom shape. I added it to the end of the BuiltInSections list in the Global section, and then I defined my shape by cloning the Cylinder entry, renaming it and setting the ClassID to match my plugin simpleSpline.

When I restart Max 2025 and create a new sweep modifier, I see my new shape at the bottom of the list of built in shapes, but selecting it does nothing. It does not use my shape and I don't see any parameter rollouts for my shape. I feel like I'm almost there, but I can't seem to figure out what to do next.

Here's my custom shape code:

plugin simpleSpline splineSegment name:"Spline Segment" classID:#(0x52617943, 0x53504C31) category:"RayScripts" usePBValidity:true ( local bezierShapeClass = dotNetClass "Autodesk.Max.MaxPlus.BezierShape" local splineKnot = dotNetClass "Autodesk.Max.MaxPlus.SplineKnot" local vector3 = dotNetClass "Autodesk.Max.MaxPlus.Point3" local bezierKnot = (dotNetClass "Autodesk.Max.MaxPlus.SplineKnot+KnotType").BezierKnot local curveLine = (dotNetClass "Autodesk.Max.MaxPlus.SplineKnot+LineType").CurveLineType local initialized = true fn vec3 xyz = dotNetObject vector3 xyz.x xyz.y xyz.z fn getSplineKnot pos inVec outVec = dotNetObject splineKnot bezierKnot curveLine (vec3 pos) (vec3 (pos + inVec)) (vec3 (pos + outVec)) fn getPointPlaneProjection pos pTM = pos + dot (pTM.translation - pos) pTM.row3 * pTM.row3 parameters main rollout:params ( segLen default:5 type:#worldUnits animatable:on ui:segLen_spn on segLen set val do if initialized do this.rebuildShape() changed default:true type:#boolean invisibleInTV:true ) fn orient &nodeTM pos = ( local projPos = getPointPlaneProjection pos nodeTM local x = normalize (projPos - nodeTM.translation) if keyboard.shiftPressed do case of ( (abs (dot x x_axis) > abs (dot x y_axis)): x = if dot x x_axis > 0 then x_axis else -x_axis (abs (dot x y_axis) > abs (dot x x_axis)): x = if dot x y_axis > 0 then y_axis else -y_axis ) local y = cross nodeTM.row3 x nodeTM = matrix3 x y (cross x y) nodeTM.translation projPos ) fn makeSeg addNext = ( addNext (getSplineKnot [segLen / -2.0, 0, 0] \ [0, 0, 0] \ [0, 0, 0]) addNext (getSplineKnot [segLen / 2.0, 0, 0] \ [0, 0, 0] \ [0, 0, 0]) ) fn rebuildShape = ( local shapeWrapper = bezierShapeClass._CreateWrapperFromFPValue BezierShape shapeWrapper.NewShape() local spline = shapeWrapper.NewSpline() makeSeg spline.AddKnot shapeWrapper.UpdateSels() shapeWrapper.InvalidateGeomCache() changed = false ) rollout params "Parameters" ( spinner segLen_spn "Segment Length: " range:[1e-9, 1e9, 5] type:#worldUnits align:#right offset:[10,0] ) tool create numPoints:2 ( local center on mousePoint click do case click of ( 1: nodeTM.translation = gridPoint ) on mouseMove click do case click of ( 2: segLen = (distance nodeTM.translation (orient &nodeTM gridPoint)) * 2.0 ) ) on create do initialized = false on postCreate do initialized = true on clone orig do segLen = segLen on buildShape do if changed do rebuildShape() )

My modification/addition to the sweep.ini

[Global] BuiltInSections= Angle,Bar,Channel,Cylinder,Half Round,Pipe,Quarter Round,Tee,Tube,Wide Flange,Egg,Ellipse,splineSegment [splineSegment] ClassID= 52617943, 53504C31 IconFile=Sweep_DefaultSections IconIndex=9 NumDefaults= 1 Default1= 0,float,10.000000

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Extending the Sweep built in shapes