Cursor point and status readouts

The point a click stands for when ortho is on and there is a base point.

u = c·Δx + s·Δy; v = −s·Δx + c·Δy; point = base + u·(c, s) if |u| ≥ |v|, else base + v·(−s, c)

The cursor's offset from the base point is projected on the two axes of the coordinate system in force, c and s being the cosine and sine of its angle. With no user coordinate system c = 1 and s = 0 exactly, so one coordinate of the result equals the base point's bit for bit and the other is base + (cursor − base), which can differ from the cursor's coordinate in the last bit. With a turned system both coordinates pass through the sine and cosine.

if (settings.ortho && base) {
  const c = Math.cos(ua), s = Math.sin(ua), dx = raw.x - base.x, dy = raw.y - base.y, u = c * dx + s * dy, v = -s * dx + c * dy;
  return Math.abs(u) >= Math.abs(v) ? { x: base.x + c * u, y: base.y + s * u } : { x: base.x - s * v, y: base.y + c * v };
}

The cursor's coordinates and, during a command, the distance and angle from the base point.

Δ = √(Δx² + Δy²); angle = atan2(Δy, Δx) − UCS angle, normalized to 0…360°

The coordinates are the point in the user coordinate system (ucs.js toUcs). The distance is one Math.hypot from the base point in world coordinates and the angle is one atan2 minus the system's angle. All three are turned into text after the calculation, so the only rounding in the readout is that of the drawing's length and angle formats.

const uc = activeUcs(doc), q = toUcs(uc, p);   // the readout is in the UCS (DR.8)
ui.coords.textContent = fmtL(q.x) + ', ' + fmtL(q.y) + (base ? '   Δ ' + fmtL(Math.hypot(p.x - base.x, p.y - base.y)) + ' < ' + fmtAngle(doc.meta, deg(normAngle(Math.atan2(p.y - base.y, p.x - base.x) - (uc?.ang || 0)))) : '');

A length written for the status line, the tracking labels and the cursor box.

In the model the value goes to units.js formatLength with the drawing's units and precision. On a sheet it goes to ui-util.js fmt, which writes at most 4 decimals and shows a value under 1e-10 in size as 0.

/** A length / an area in the drawing's format (paper units on a sheet stay decimal). */
function fmtL(v) { return doc.layout ? fmt(v) : formatLength(v, unitsOf(doc.meta)); }

The live distance or angle shown in the box by the cursor while a command waits for one.

d = √(Δx² + Δy²); angle = atan2(Δy, Δx), normalized to 0…360°

One Math.hypot or one atan2 from the prompt's base point to the cursor, written with the same formats as the status line. Text being typed is shown in place of the computed value.

} else if (w.kind === 'distance' && w.opts.base) parts.push(el('span', { className: 'cc-dyn-f is-active' }, typedNow || fmtL(Math.hypot(cur.x - w.opts.base.x, cur.y - w.opts.base.y))));
else if (w.kind === 'angle' && w.opts.base) parts.push(el('span', { className: 'cc-dyn-f is-active' }, typedNow || fmtAngle(doc.meta, deg(normAngle(Math.atan2(cur.y - w.opts.base.y, cur.x - w.opts.base.x)))) ));

The width and height of the chosen area at the chosen scale, shown in the Plot dialog.

w = (maxX − minX) × s, shown as round(w × 10) ÷ 10

The area's extent is multiplied by the sheet's scale factor and rounded to 0.1 with Math.round(v × 10) ÷ 10 for the dialog's information line. The rounded value is only shown; the sheet comes from plot.js modelSheet, which is given the unrounded area.

const mm = (v) => fmt(Math.round(v * 10) / 10);
const info = t(sheet.scale.fits ? 'app.plot.area' : 'app.plot.area.toobig', { scale: sheet.scale.label, w: mm((area.maxX - area.minX) * sheet.scale.s), h: mm((area.maxY - area.minY) * sheet.scale.s) });

The number a property is compared with in the Quick select dialog.

The text is read as a length in the drawing's format by units.js parseLength. When that returns null it falls back to parseFloat, which reads a leading number and ignores anything after it, so 12abc is taken as 12.

value = () => (P.kind === 'number' ? (parseLength(inp.value, doc.meta.lunits, doc.meta.units) ?? parseFloat(inp.value)) : inp.value);