Resources Numerical accuracy Calculation policy
Reads pipe segments, fittings and valves from an IFC file and gives their end points, bores, bend angles and center points in millimeters.
End points come from the port placements or from the two ends of the extruded body, through the element's world matrix, and are multiplied by the file's length unit times 1000 to give millimeters. All of it is 64-bit. The turn angle of a bend is rounded to 0.01 degree before it is kept.
4 calculations in 1 source file. The code is read from the released app when this page loads. It is the calculation people run, not a copy kept for this page.
Tests bin/test-ifc43.mjs
Where a port is, in millimeters, and the way it faces.
p = M · (0, 0, 0) × mm; z = normalize(M · (0, 0, 1) direction)
The port's world matrix gives the point, which is multiplied by the file's length unit × 1000. The direction is the matrix's Z column, normalized.
const portPoint = (pid) => { const m = g.placement(ref(g.a(pid, 'ObjectPlacement'))); return { p: apply(m, 0, 0, 0).map((v) => v * mm), z: norm(applyDir(m, 0, 0, 1)) }; };The two ends of a pipe segment and its bore from its extruded solid.
a = T · 0; b = T · (direction × depth); bore = 2 × radius × mm
T is the element's world matrix times the solid's position. The far end is the extrusion direction times the depth, transformed; the bore is twice the circle profile's radius, or 0 for any other profile.
const bodyOf = (id) => { // { a, b, bore } from the extruded body, or null
const pds = ref(g.a(id, 'Representation'));
if (pds === null) return null;
const M = g.placement(ref(g.a(id, 'ObjectPlacement')));
for (const sr of refs(g.a(pds, 'Representations'))) {
for (const item of refs(g.a(sr, 'Items'))) {
if (file.type(item) !== 'IFCEXTRUDEDAREASOLID') continue;
const pos = g.axis2(ref(g.a(item, 'Position')));
const T = mul(M, pos);
const d = g.dir(ref(g.a(item, 'ExtrudedDirection')), [0, 0, 1]);
const depth = g.num(g.a(item, 'Depth'), 0);
const prof = ref(g.a(item, 'SweptArea'));
const t = prof !== null ? file.type(prof) : null;
const r = t === 'IFCCIRCLEPROFILEDEF' || t === 'IFCCIRCLEHOLLOWPROFILEDEF' ? g.num(g.a(prof, 'Radius'), 0) : 0;
return { a: apply(T, 0, 0, 0).map((v) => v * mm), b: apply(T, d[0] * depth, d[1] * depth, d[2] * depth).map((v) => v * mm), bore: 2 * r * mm };The angle a two-port fitting turns the pipe through.
turn = 180 − acos(p · q) × 180 ÷ π, rounded to 2 decimals
The dot product of the two outward unit directions is clamped to [−1, 1] before acos. For a nearly straight fitting the dot product is near −1, where acos loses digits. The result is rounded to 0.01 degree with toFixed(2), and that rounded value is what the component keeps.
const between = (Math.acos(Math.max(-1, Math.min(1, dot(p.d, q.d)))) * 180) / Math.PI; // 180° apart = straight
const turn = +(180 - between).toFixed(2); // the angle the pipe turns throughThe corner where the axes of a bend's two ports meet.
s = (b e − c d) ÷ (a c − b²), t = (a e − b d) ÷ (a c − b²); center = midpoint of the two closest points
The closest points of the two axis lines are solved in closed form. The denominator a c − b² is the squared sine of the angle between the unit directions, so it is small for a slight bend and the corner then has few good digits. The solve is skipped, and the midpoint of the ports used, when the cross product is shorter than 1e-6.
const n = cross(p.d, q.d);
let centre = mid;
if (len(n) > 1e-6) { // lines p.p + s·p.d and q.p + t·q.d meet at the corner
const w = sub(p.p, q.p), a = dot(p.d, p.d), b = dot(p.d, q.d), c = dot(q.d, q.d), d = dot(p.d, w), e = dot(q.d, w), den = a * c - b * b;
const s = (b * e - c * d) / den, t = (a * e - b * d) / den;
centre = scale(add(add(p.p, scale(p.d, s)), add(q.p, scale(q.d, t))), 0.5);
}Every value is a 64-bit number from input to result. Formulas are closed form or a direct solve, and every comparison uses a stated tolerance.