Extending the Sweep built in shapes

[Ray.Collett]

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