Reading Your Sketch: Appearance, Degrees of Freedom, and Selection

Pingendum 2D is a drafting product, so a curve's appearance describes what it is in the drawing — which layer it belongs to, how heavily it plots, whether it's a hidden line — and not how constrained it is. That's the opposite of a pure sketcher, and it's the single most useful thing to know about reading the canvas.

Constraint state hasn't gone anywhere; it just isn't a colour. It's a number in the status bar.

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Prerequisites

Before you begin, ensure that:

• You've completed Constraining a Sketch and can apply a few constraints.

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Where a Curve's Appearance Comes From

Three properties decide how a curve is drawn, and all three work the same way: each is ByLayer unless you override it on the object itself.

So the fastest way to make a whole class of geometry read differently is to put it on its own layer — and the fastest way to make one curve stand out is to override it directly. The Properties panel shows which of the two you're looking at. Setting layers up is covered in Working with Layers.

Note: why a new drawing is all cyan

Everything you draw lands on layer 0, the default layer that every drawing has and that can't be deleted. Layer 0 is cyan #00FFFF at 0.25 mm — a high-contrast combination on the dark canvas, and the reason a fresh sketch comes out uniformly cyan whether it's constrained or not.

That's worth knowing because cyan is easy to misread as a status. It isn't one. Add a second layer in a different colour and the point becomes obvious: two fully constrained lines on two layers draw in two colours.

0.25 mm is also the thinnest weight that reads on screen — it renders as a 1 px hairline — so every heavier lineweight you set grows visibly from there.

Note: lineweight is a paper property

Lineweight is measured in millimetres on the plotted sheet. On screen it's shown at roughly 4 pixels per millimetre — so a 0.5 mm line draws about 2 px wide — and it does not scale as you zoom. A hairline stays a hairline whether you're zoomed in or out, which is what makes relative weights readable at any zoom.

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Layer States: Off, Frozen, and Locked

These three are easy to confuse and they behave differently. The distinction matters because two of them leave geometry you can still act on.

• Off hides a layer and nothing else. Its geometry is still part of the drawing, still counts toward the view extents, and Ctrl+A still selects it. Turning a layer off to get it out of the way does not put it out of reach.
• Frozen removes it from the working set entirely — invisible, unreachable by any selection, excluded from extents.
• Locked keeps it visible and pickable but refuses every edit. Its colour is blended halfway toward the canvas, so a locked reference layer reads as present-but-quiet rather than disappearing.

Locked geometry is deliberately still snappable — a locked reference layer is exactly the thing you want to snap new geometry to. All three states are set from the Layers panel (Working with Layers).

Note: a refusal tells you which layer

Try to drag, nudge, delete or constrain something on a locked layer and Pingendum names the layer rather than failing silently: "Layer "Walls" is locked. Unlock it in the Layers panel to edit what is on it." Frozen layers and hidden objects each get their own sentence.

A mixed selection does the part it's allowed to and reports the rest — deleting six objects when two of them are locked removes four and tells you "2 of 6 selected objects were not deleted", followed by the reason.

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What You're Pointing At

Two states are painted on top of whatever the drawing's own style says, so you never lose track of the cursor:

• Hover — the entity under the cursor turns cyan #00FFFF, drawn heavier and above everything else. This is a preview of what a click will select.
• Selected — a confirmed selection is green #1CAD1C, drawn as an overlay.

Click empty space and both clear, returning the geometry to its layer appearance.

Selection outranks hover, and hover outranks the drawing's own style — so a selected object stays green while you move the cursor over it.

Tip: clicking the same spot twice cycles

Where several objects overlap, a plain click picks the nearest and the status bar says so — "3 overlapping items — click again to cycle". Clicking again without moving steps to the next candidate, so stacked geometry is always reachable without moving anything out of the way.

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Construction Geometry

Construction geometry — the reference-only lines you mark with the Construction toggle (G) — is the one kind of geometry that keeps its own appearance regardless of layer. It is drawn:

• dashed, in every state,
• at a thinner weight than real geometry,
• in green #73B373, turning cyan #00FFFF while it still has freedom left.

That makes it identifiable at a glance, and it's why a centreline or a bisector never gets mistaken for part of the finished outline. It's also excluded from plotting unless you ask for it in the sheet setup.

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Point Markers

Points are coloured on their own terms too, not by the layer of the curve that owns them:

Centres get their own colour so you can pick the centre of a circle without hunting among the endpoints sitting near it.

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Reading the Sketch's State

Since colour doesn't report it, the DOF readout in the status bar is where you look. It shows one of four things:

That readout is the whole of the on-screen solver report. There is no badge on the canvas, no warning colour, and no per-entity indication of which pieces are still loose.

Tip: drag to find the freedom

Because you can't see which entity is loose, the practical technique is to drag. Grab something and see whether it moves, and in which direction — a line that slides sideways needs a position constraint, one that stretches needs a length. Fully constrained geometry won't move at all, which is itself the answer.

Escape mid-drag puts everything back, so this is free to try.

For anything the DOF number can't tell you — redundant constraints, degenerate geometry, near-miss gaps — run Drawing → Validate drawing (Diagnosing Sketches). And for the case where the numbers are simply impossible and the geometry quietly stops responding, see When a Sketch Won't Solve.

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How This Interacts With Other Feedback

• Edit handles appear on selected slots, arc slots and conics — small grips for their individual parameters, drawn on top of the selection overlay. Ordinary lines, circles and arcs have none; you drag those directly (see Moving and Duplicating a Selection).
• Constraint glyphs — the small horizontal, parallel, tangent and equal badges — are drawn over the sketch and can be turned off from View → Constraint icons. They're on by default.
• Dimensions are drawn separately from geometry and follow the layer of the object they measure, so a dimension on a hidden layer's geometry hides with it.

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Next Steps

You now know how to:

• Predict a curve's colour, weight and dash from its layer or its own override
• Tell an off layer from a frozen one and from a locked one, and know what each still lets you do
• Recognize the hover and selection overlays, and cycle through stacked geometry
• Spot construction geometry and read the point-marker colours
• Find the sketch's solver state in the status bar, and use drag-to-test to locate remaining freedom

The next chapter puts selection to work: moving and duplicating the geometry you've selected, directly on the canvas.

Next: Moving and Duplicating a Selection