Softening edges

Curved shapes in Modlumi are made of flat faces. Softening the edges between those faces hides their lines, and smoothing them shades the faces as one curved surface, so a cylinder with 24 sides looks round instead of faceted. Models imported from SketchUp files and 3D text come with their soft edges already set.

Each edge has two flags:

• Soft hides the edge’s line. The faces on both sides still exist and stay separate; only the line between them is gone.
• Smooth shades the faces on both sides of the edge as one curved surface instead of giving each face its own flat shade.

Softened edges are usually smooth too, and the commands below set both together unless you choose otherwise.

The Soften Edges panel

Open the Soften Edges panel from Window → Soften Edges, or right-click selected edges and choose Soften/Smooth Edges. The panel acts on the selected edges: select the geometry first, for example by triple-clicking it or dragging a selection box around it.

• Angle between normals is the largest angle between the two faces of an edge that softens it. Edges whose faces turn by more stay hard, and edges that were soft but turn by more become hard again. Drag the slider, or Ctrl+click it to type an angle. At 0 nothing softens; at 180 every edge between two faces does.
• Smooth normals smooths the edges it softens. Turn it off to hide the lines but keep each face’s own shade.
• Soften coplanar also softens edges between faces that lie in one plane, which the angle alone leaves hard.

The selection updates as you change a setting, so you can watch the surface while you drag. One drag, or any run of changes to the same selection, is one undo step.

Only edges with exactly two faces change. Lone edges and edges along the border of a single face keep their flags; use the Eraser or the Properties panel to soften those.

Soften single edges

With the Eraser (E), a modifier key changes what clicking or dragging across edges does, instead of erasing them:

• Press Ctrl (Option on macOS) to soften and smooth edges.
• Press Alt (Command on macOS) to unsoften edges: they become neither soft nor smooth. Soft edges can only be pointed at while View → Hidden Geometry shows them.
• Hold Shift to hide edges.

Ctrl and Alt switch their mode on when you press them, and off when you press them again, so you don’t have to hold them; the Eraser’s guidance shows which mode is on. Holding Shift while softening unsoftens instead, as Ctrl+Shift did in older versions. Each click or drag is one undo step. Modifiers only change edges in the group or component you’re editing; guides, text, dimensions and closed groups are left alone.

Edge properties

Select one or more edges and open Window → Properties to see their Soft and Smooth check boxes. A box shows a dash when some of the selected edges have the flag and others don’t; clicking it sets the flag on all of them.

Right-click selected edges and choose Unsoften Edges to clear both flags at once.

Seeing and picking soft edges

Soft edges aren’t drawn, and clicks pass through them to the faces behind, so you can’t select or erase them by pointing. Faces joined by soft edges act as one surface: clicking any of them selects the whole surface with its soft edges, double-clicking adds the edges around it, and right-clicking it does the same as clicking. A selection box still selects the soft edges inside it. Inferences still snap to the points and edges of a smoothed surface.

Choose View → Hidden Geometry to show soft edges as dotted lines. Then they can be clicked, and clicking a face selects that face alone.

In scripts

Scripts read and change the flags with edge.soft and edge.smooth. See Geometry.