ifc_lite_geometry/
alignment_axis.rs

1// This Source Code Form is subject to the terms of the Mozilla Public
2// License, v. 2.0. If a copy of the MPL was not distributed with this
3// file, You can obtain one at https://mozilla.org/MPL/2.0/.
4
5//! The one answer to "which curve is this `IfcAlignment`'s directrix?",
6//! shared by the alignment processor (`processors/alignment.rs`) and the
7//! wasm centerline overlay (`wasm-bindings/src/api/alignment_lines.rs`).
8//! Two private copies of this lookup used to exist and could silently
9//! disagree about what an alignment's axis is (#5327).
10
11use ifc_lite_core::{DecodedEntity, EntityDecoder, IfcType};
12
13/// Resolve an `IfcAlignment`'s directrix curve.
14///
15/// IFC4X1 puts `Axis` at attribute 7; some publishers reuse `Representation`
16/// (6) or hang it at 8. Accept the first ref that resolves to an
17/// `IfcAlignmentCurve` or `IfcPolyline` (the curves `AlignmentCurve::parse`
18/// understands). A ref that fails to resolve is skipped, not fatal.
19/// Otherwise IFC4x3 `Representation` (attr 6) supplies the `'Axis'` shape
20/// representation's curve (`IfcGradientCurve`; an
21/// `IfcSegmentedReferenceCurve` contributes its gradient `BaseCurve`), or
22/// the `'FootPrint'` 2D curve. `None` when neither path yields a curve.
23pub fn locate_axis_curve(entity: &DecodedEntity, decoder: &mut EntityDecoder) -> Option<DecodedEntity> {
24    let alignment_curve = IfcType::from_str("IFCALIGNMENTCURVE");
25    for idx in [7usize, 8, 6] {
26        let Some(attr) = entity.get(idx) else { continue };
27        if attr.is_null() {
28            continue;
29        }
30        if let Ok(Some(resolved)) = decoder.resolve_ref(attr) {
31            if resolved.ifc_type == alignment_curve || resolved.ifc_type == IfcType::IfcPolyline {
32                return Some(resolved);
33            }
34        }
35    }
36    representation_axis_curve(entity, decoder)
37}
38
39/// IFC4x3 path of [`locate_axis_curve`]: prefer the `'Axis'` representation
40/// (3D, carries the vertical profile) over `'FootPrint'` (plan only).
41fn representation_axis_curve(entity: &DecodedEntity, decoder: &mut EntityDecoder) -> Option<DecodedEntity> {
42    let shape = decoder.decode_by_id(entity.get_ref(6)?).ok()?;
43    if shape.ifc_type != IfcType::IfcProductDefinitionShape {
44        return None;
45    }
46    let mut footprint = None;
47    for rep_id in shape.get_refs(2)? {
48        let Ok(rep) = decoder.decode_by_id(rep_id) else { continue };
49        let identifier = rep.get(1).and_then(|v| v.as_string()).unwrap_or("").to_ascii_uppercase();
50        for item_id in rep.get_refs(3).unwrap_or_default() {
51            let Ok(item) = decoder.decode_by_id(item_id) else { continue };
52            let curve = if item.ifc_type == IfcType::IfcSegmentedReferenceCurve {
53                // IfcSegmentedReferenceCurve: 0 Segments, 1 SelfIntersect, 2 BaseCurve
54                match item.get_ref(2).and_then(|id| decoder.decode_by_id(id).ok()) {
55                    Some(base) => base,
56                    None => continue,
57                }
58            } else {
59                item
60            };
61            let usable = matches!(
62                curve.ifc_type,
63                IfcType::IfcGradientCurve | IfcType::IfcPolyline | IfcType::IfcCompositeCurve
64            );
65            if !usable {
66                continue;
67            }
68            if identifier == "AXIS" {
69                return Some(curve);
70            }
71            if identifier == "FOOTPRINT" && footprint.is_none() {
72                footprint = Some(curve);
73            }
74        }
75    }
76    footprint
77}
ifc_lite_geometry/alignment_axis.rs

ifc_lite_geometry/
alignment_axis.rs
