Struct AlignmentCurve 

pub struct AlignmentCurve { /* private fields */ }

Parsed alignment curve. Holds horizontal and vertical segments in authored order with cumulative-start stations precomputed.

Implementations

impl AlignmentCurve

pub fn parse( directrix: &DecodedEntity, decoder: &mut EntityDecoder<'_>, ) -> Result<Option<Self>>

Parse IfcAlignmentCurve (or any directrix we can reduce to a piecewise alignment). Recognised cases:

• IfcAlignmentCurve — full horizontal + vertical + (optional) cant parsing.
• IfcPolyline — synthesised as a chain of line segments. Each polyline edge becomes one HSeg::Line (in XY) and one VSeg::Line (with gradient = dz / horizontal length). This covers the relatively rare case of a sectioned-solid authored with a polyline directrix, which is spec-allowed but uncommon.

Returns Ok(None) for any other directrix so the caller can fall back to a straight-line sweep. Errors only on malformed recognised input (e.g. an IfcAlignmentCurve missing Horizontal).

pub fn with_cant_segments(self, segments: Vec<CantSegSpec>) -> Self

Attach a pre-parsed cant profile. Used by callers that have already located an IfcAlignment2DCant entity for this alignment (e.g. via an IfcAlignment.AxisCant traversal). The segments are taken in authored order with cumulative-station indexing handled by cant_angle.

pub fn auto_attach_cant( self, content: &str, decoder: &mut EntityDecoder<'_>, ) -> Result<Self>

Scan content for any IfcAlignment2DCant and attach the first one found. This is a best-effort hook for callers that want the auto-discovery convenience; in IFC4x1 the schema doesn’t constrain how the cant is bound to the alignment, so picking the first one is the only generic option. Files with multiple alignments + cants should use with_cant_segments explicitly.

pub fn horizontal_length(&self) -> f64

Total length of the horizontal alignment (sum of segment lengths).

pub fn evaluate(&self, station: f64) -> AlignmentFrame

Evaluate the placement frame at the given station (cumulative distance along the horizontal alignment, in file length units). Extrapolates linearly past either end.

pub fn cant_angle(&self, station: f64) -> f64

Cant (roll about the 3D tangent) at the given station, in radians. Returns 0 when no cant is authored.