ifc_geometry/constraint/
grid.rs

1//! `IfcGrid` placement: positioning against construction grid axes.
2//!
3//! Structural and architectural drawings lay out elements against a grid
4//! ("column at C-4") rather than by coordinate. `IfcGridPlacement` encodes
5//! that directly, so the placement is *derived* from two axis curves rather
6//! than stated as a transform.
7//!
8//! # Why this is not just another placement
9//!
10//! [`super::local::LocalPlacement`] composes stored transforms. A grid
11//! placement has no stored transform at all: the position is the intersection
12//! of two curves, which must be computed. That needs curve evaluation, which
13//! is the geometry kernel's job, so this module exposes the inputs and stops
14//! there.
15
16use crate::error::GeometryResult;
17use crate::slots::Slots;
18use ifc_model::{Entity, EntityId};
19
20/// `IfcGridAxis` attribute slots.
21pub(crate) mod axis_slot {
22    /// `AxisTag`: the label, e.g. `C` or `4`.
23    pub const AXIS_TAG: usize = 0;
24    /// `AxisCurve`: the curve the axis follows.
25    pub const AXIS_CURVE: usize = 1;
26    /// `SameSense`: whether the curve direction agrees with the axis.
27    pub const SAME_SENSE: usize = 2;
28}
29
30/// `IfcVirtualGridIntersection` attribute slots.
31pub(crate) mod intersection_slot {
32    /// `IntersectingAxes`: exactly two `IfcGridAxis`.
33    pub const INTERSECTING_AXES: usize = 0;
34    /// `OffsetDistances`: two or three offsets from the intersection.
35    pub const OFFSET_DISTANCES: usize = 1;
36}
37
38/// `IfcGridPlacement` attribute slots.
39pub(crate) mod placement_slot {
40    /// `PlacementLocation`: the grid intersection.
41    pub const PLACEMENT_LOCATION: usize = 0;
42    /// `PlacementRefDirection`: optional direction reference.
43    pub const PLACEMENT_REF_DIRECTION: usize = 1;
44}
45
46/// A borrowed view of an `IfcGridAxis`.
47#[derive(Debug, Clone, Copy)]
48pub struct GridAxis<'m> {
49    slots: Slots<'m>,
50}
51
52impl<'m> GridAxis<'m> {
53    /// Wrap an entity assumed to be an `IfcGridAxis`.
54    pub fn new(id: EntityId, entity: &'m Entity) -> Self {
55        Self {
56            slots: Slots::new(id, entity),
57        }
58    }
59
60    /// The entity id.
61    pub fn id(&self) -> EntityId {
62        self.slots.id()
63    }
64
65    /// The axis label, e.g. `C` or `4`.
66    pub fn tag(&self) -> Option<&'m str> {
67        self.slots.opt(axis_slot::AXIS_TAG)?.as_text()
68    }
69
70    /// The curve this axis follows.
71    pub fn curve(&self) -> GeometryResult<EntityId> {
72        self.slots.req_ref(axis_slot::AXIS_CURVE, "AxisCurve")
73    }
74
75    /// Whether the axis direction agrees with its curve's direction.
76    ///
77    /// Required by the schema, but defaulted to `true` when a file omits it:
78    /// a missing sense flag should not make a grid unusable.
79    pub fn same_sense(&self) -> bool {
80        self.slots.opt_bool(axis_slot::SAME_SENSE).unwrap_or(true)
81    }
82}
83
84/// A borrowed view of an `IfcVirtualGridIntersection`.
85///
86/// "Virtual" because the axes need not physically cross: the intersection is a
87/// computed point, optionally offset.
88#[derive(Debug, Clone, Copy)]
89pub struct VirtualGridIntersection<'m> {
90    slots: Slots<'m>,
91}
92
93impl<'m> VirtualGridIntersection<'m> {
94    /// Wrap an entity assumed to be an `IfcVirtualGridIntersection`.
95    pub fn new(id: EntityId, entity: &'m Entity) -> Self {
96        Self {
97            slots: Slots::new(id, entity),
98        }
99    }
100
101    /// The entity id.
102    pub fn id(&self) -> EntityId {
103        self.slots.id()
104    }
105
106    /// The two intersecting axes.
107    ///
108    /// The schema constrains this to exactly two; a file with a different
109    /// count is returned as-is so the caller can report it rather than having
110    /// the truth hidden here.
111    pub fn axes(&self) -> GeometryResult<Vec<EntityId>> {
112        self.slots
113            .req_ref_list(intersection_slot::INTERSECTING_AXES, "IntersectingAxes")
114    }
115
116    /// Offsets from the computed intersection.
117    ///
118    /// Two or three values: along the first axis, along the second, and
119    /// optionally along Z. In the file's length unit, so unconverted.
120    pub fn offsets(&self) -> GeometryResult<Vec<f64>> {
121        self.slots
122            .req_f64_list(intersection_slot::OFFSET_DISTANCES, "OffsetDistances")
123    }
124}
125
126/// A borrowed view of an `IfcGridPlacement`.
127#[derive(Debug, Clone, Copy)]
128pub struct GridPlacement<'m> {
129    slots: Slots<'m>,
130}
131
132impl<'m> GridPlacement<'m> {
133    /// Wrap an entity assumed to be an `IfcGridPlacement`.
134    pub fn new(id: EntityId, entity: &'m Entity) -> Self {
135        Self {
136            slots: Slots::new(id, entity),
137        }
138    }
139
140    /// The entity id.
141    pub fn id(&self) -> EntityId {
142        self.slots.id()
143    }
144
145    /// The grid intersection this placement sits at.
146    pub fn location(&self) -> GeometryResult<EntityId> {
147        self.slots
148            .req_ref(placement_slot::PLACEMENT_LOCATION, "PlacementLocation")
149    }
150
151    /// Optional reference direction.
152    ///
153    /// `IfcGridPlacementDirectionSelect`: either an `IfcDirection` or a second
154    /// `IfcVirtualGridIntersection` pointing at it. Returned as a raw id
155    /// because the caller must dispatch on the target's type.
156    pub fn ref_direction(&self) -> Option<EntityId> {
157        self.slots.opt_ref(placement_slot::PLACEMENT_REF_DIRECTION)
158    }
159}
160
161#[cfg(test)]
162mod tests {
163    use super::*;
164    use ifc_model::Value;
165
166    #[test]
167    fn reads_axis_tag_and_curve() {
168        let e = Entity::new(
169            "IFCGRIDAXIS",
170            vec![
171                Value::Text("C".into()),
172                Value::Ref(EntityId(5)),
173                Value::Bool(true),
174            ],
175        );
176        let axis = GridAxis::new(EntityId(1), &e);
177        assert_eq!(axis.tag(), Some("C"));
178        assert_eq!(axis.curve().unwrap(), EntityId(5));
179        assert!(axis.same_sense());
180    }
181
182    /// A missing sense flag must not make the grid unusable.
183    #[test]
184    fn absent_same_sense_defaults_to_true() {
185        let e = Entity::new(
186            "IFCGRIDAXIS",
187            vec![
188                Value::Text("4".into()),
189                Value::Ref(EntityId(5)),
190                Value::Null,
191            ],
192        );
193        assert!(GridAxis::new(EntityId(1), &e).same_sense());
194    }
195
196    #[test]
197    fn reads_intersection_axes_and_offsets() {
198        let e = Entity::new(
199            "IFCVIRTUALGRIDINTERSECTION",
200            vec![
201                Value::List(vec![Value::Ref(EntityId(1)), Value::Ref(EntityId(2))]),
202                Value::List(vec![Value::Real(0.5), Value::Real(-0.25)]),
203            ],
204        );
205        let x = VirtualGridIntersection::new(EntityId(3), &e);
206        assert_eq!(x.axes().unwrap().len(), 2);
207        assert_eq!(x.offsets().unwrap(), vec![0.5, -0.25]);
208    }
209
210    #[test]
211    fn ref_direction_is_optional() {
212        let e = Entity::new(
213            "IFCGRIDPLACEMENT",
214            vec![Value::Ref(EntityId(9)), Value::Null],
215        );
216        let p = GridPlacement::new(EntityId(1), &e);
217        assert_eq!(p.location().unwrap(), EntityId(9));
218        assert_eq!(p.ref_direction(), None);
219    }
220}
ifc_geometry/constraint/grid.rs

ifc_geometry/constraint/
grid.rs
