Surface Loft: sheets through open or closed sections (#847)

Surface Loft lofts open or closed curve chains, one section per sketch in pick order, into surface bodies. Adds the SurfaceLoft feature (format 18 note), the surface.loft command, a dialog with Edit Feature support, and kernel and engine tests.

Part of #757.

crates/doc/src/assembly.rs

@@ -325,6 +325,7 @@ impl FeatureKind {
             | FeatureKind::SurfaceExtrude { .. }
             | FeatureKind::SurfaceRevolve { .. }
             | FeatureKind::SurfaceSweep { .. }
+            | FeatureKind::SurfaceLoft { .. }
             | FeatureKind::Combine { .. }
             | FeatureKind::Loft { .. }
             | FeatureKind::Sweep { .. }

crates/doc/src/clipboard.rs

@@ -62,6 +62,7 @@ impl FeatureKind {
             FeatureKind::Pipe { path_sketch, .. } => sk(path_sketch),
             FeatureKind::SheetFold { sketch: Some(s), .. } => sk(s),
             FeatureKind::Loft { sections, .. } => sections.iter_mut().for_each(|s| sk(&mut s.sketch)),
+            FeatureKind::SurfaceLoft { sections } => sections.iter_mut().for_each(|s| sk(&mut s.sketch)),
             FeatureKind::Hole { points: Some(p), .. } => sk(&mut p.sketch),
             FeatureKind::Pattern { features, pattern, .. } => {
                 feats(features);

crates/doc/src/document.rs

@@ -982,6 +982,11 @@ pub enum FeatureKind {
         path_sketch: u64,
         path: Vec<String>,
     },
+    /// A surface body lofted through sections in order, each one open or closed chain of
+    /// sketch curves: walls only, no caps.
+    SurfaceLoft {
+        sections: Vec<SheetSection>,
+    },
     /// A planar surface body extended outward by `distance` past the edges through `edges`.
     SurfaceExtend {
         body: String,
@@ -1136,6 +1141,17 @@ pub struct LoftSection {
     pub point: Option<String>,
 }
 
+/// A section of a surface loft: one chain from a sketch (one profile's boundary, or curves
+/// meeting end to end).
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
+pub struct SheetSection {
+    pub sketch: u64,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub profiles: Option<ProfileSel>,
+    #[serde(default, skip_serializing_if = "Vec::is_empty")]
+    pub curves: Vec<String>,
+}
+
 /// Coil cross-sections.
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Default, Serialize, Deserialize)]
 #[serde(rename_all = "snake_case")]
@@ -1292,6 +1308,7 @@ impl FeatureKind {
             K::Sweep { sketch, path_sketch, .. } | K::SurfaceSweep { sketch, path_sketch, .. } => vec![*sketch, *path_sketch],
             K::Pipe { path_sketch, .. } | K::Pattern { pattern: PatternKind::Path { path_sketch, .. }, .. } => vec![*path_sketch],
             K::Loft { sections, .. } => sections.iter().map(|s| s.sketch).collect(),
+            K::SurfaceLoft { sections } => sections.iter().map(|s| s.sketch).collect(),
             K::SheetFold { sketch, .. } | K::SplitFace { sketch, .. } | K::Patch { sketch, .. } => sketch.iter().copied().collect(),
             K::Hole { points, .. } => points.iter().map(|p| p.sketch).collect(),
             K::Sketch { .. }
@@ -1420,6 +1437,7 @@ impl FeatureKind {
             FeatureKind::SurfaceExtrude { .. } => "SurfaceExtrudeFeature",
             FeatureKind::SurfaceRevolve { .. } => "SurfaceRevolveFeature",
             FeatureKind::SurfaceSweep { .. } => "SurfaceSweepFeature",
+            FeatureKind::SurfaceLoft { .. } => "SurfaceLoftFeature",
             FeatureKind::Stitch { .. } => "StitchFeature",
             FeatureKind::Thicken { .. } => "ThickenFeature",
             FeatureKind::SurfaceTrim { .. } => "TrimFeature",
@@ -1491,6 +1509,7 @@ impl FeatureKind {
             FeatureKind::SurfaceExtrude { .. } => "SurfaceExtrude",
             FeatureKind::SurfaceRevolve { .. } => "SurfaceRevolve",
             FeatureKind::SurfaceSweep { .. } => "SurfaceSweep",
+            FeatureKind::SurfaceLoft { .. } => "SurfaceLoft",
             FeatureKind::Stitch { .. } => "Stitch",
             FeatureKind::Thicken { .. } => "Thicken",
             FeatureKind::SurfaceTrim { .. } => "Trim",
@@ -1520,6 +1539,7 @@ impl FeatureKind {
                 vec![(*sk, profiles)]
             }
             FeatureKind::Loft { sections, .. } => sections.iter_mut().filter(|s| s.point.is_none()).map(|s| (s.sketch, &mut s.profiles)).collect(),
+            FeatureKind::SurfaceLoft { sections } => sections.iter_mut().filter_map(|s| Some((s.sketch, s.profiles.as_mut()?))).collect(),
             _ => Vec::new(),
         }
     }
@@ -1541,6 +1561,7 @@ impl FeatureKind {
             FeatureKind::Loft { sections, .. } => {
                 sections.iter().filter(|section| section.point.is_none()).map(|section| (section.sketch, &section.profiles)).collect()
             }
+            FeatureKind::SurfaceLoft { sections } => sections.iter().filter_map(|s| Some((s.sketch, s.profiles.as_ref()?))).collect(),
             _ => Vec::new(),
         }
     }
@@ -1648,7 +1669,7 @@ impl FeatureKind {
             },
             FeatureKind::Mirror { plane, .. } => plane_exprs(plane, &mut v),
             FeatureKind::Shell { thickness, .. } => v.push(thickness),
-            FeatureKind::Loft { .. } | FeatureKind::Sweep { .. } | FeatureKind::SurfaceSweep { .. } => {}
+            FeatureKind::Loft { .. } | FeatureKind::Sweep { .. } | FeatureKind::SurfaceSweep { .. } | FeatureKind::SurfaceLoft { .. } => {}
             FeatureKind::Draft { angle, neutral, .. } => {
                 v.push(angle);
                 plane_exprs(neutral, &mut v);

crates/doc/src/eval.rs

@@ -3637,7 +3637,8 @@ fn eval_feature(doc: &Document, vals: &BTreeMap<String, Value>, f: &Feature, st:
         | FeatureKind::Unstitch { .. }
         | FeatureKind::ReverseNormal { .. }
         | FeatureKind::SurfaceRevolve { .. }
-        | FeatureKind::SurfaceSweep { .. } => surface::eval(doc, vals, f, st),
+        | FeatureKind::SurfaceSweep { .. }
+        | FeatureKind::SurfaceLoft { .. } => surface::eval(doc, vals, f, st),
         FeatureKind::Emboss { .. }
         | FeatureKind::Rib { .. }
         | FeatureKind::ReplaceFace { .. }

crates/doc/src/eval_surface.rs

@@ -1,5 +1,5 @@
 //! Evaluation of the surface features: Patch, Stitch, Thicken, Trim, Extend, Surface Extrude,
-//! Revolve and Sweep, Unstitch and Reverse Normal (kernel `surfaces`).
+//! Revolve, Sweep and Loft, Unstitch and Reverse Normal (kernel `surfaces`).
 
 use super::*;
 use solidcraft_geom::Seg2;
@@ -181,6 +181,32 @@ pub(super) fn eval(doc: &Document, vals: &BTreeMap<String, Value>, f: &Feature,
             st.bodies.push(ModelBody::new(name, body, f.id));
             Ok(())
         }
+        FeatureKind::SurfaceLoft { sections } => {
+            let mut secs = Vec::with_capacity(sections.len());
+            for sec in sections {
+                let ss = sketch_in_feature_frame(
+                    doc,
+                    st.sketch(sec.sketch)
+                        .ok_or_else(|| DocError::Unknown(format!("sketch {} (it must come earlier in the timeline)", sec.sketch)))?,
+                    f.component,
+                )?;
+                let profiles = match (&sec.profiles, sec.curves.is_empty()) {
+                    (None, true) => Some(&ProfileSel::All),
+                    (p, _) => p.as_ref(),
+                };
+                let mut chains = sheet_chains(&ss, profiles, &sec.curves)?.into_iter();
+                let (Some(chain), None) = (chains.next(), chains.next()) else {
+                    return Err(DocError::Invalid(
+                        "each loft section must be one chain: one profile without holes, or curves meeting end to end".into(),
+                    ));
+                };
+                secs.push((ss.plane, chain));
+            }
+            let body = kernel::loft_sheet(&secs)?;
+            let name = new_name(st, f, 0);
+            st.bodies.push(ModelBody::new(name, body, f.id));
+            Ok(())
+        }
         _ => Err(DocError::Invalid("not a surface feature".into())),
     }
 }

crates/doc/src/format.rs

@@ -120,6 +120,8 @@
 //!   `axis`, `angle`, optional `angle2` and `symmetric`) is also first saved in 18.
 //!   A `SurfaceSweep` feature (Surface Sweep: `sketch`, optional `profiles` and `curves`,
 //!   `path_sketch`, `path`) is also first saved in 18.
+//!   A `SurfaceLoft` feature (Surface Loft: `sections`, each a `sketch` with optional `profiles`
+//!   and `curves`) is also first saved in 18.
 
 use serde_json::Value;
 

crates/doc/src/params.rs

@@ -290,6 +290,7 @@ impl FeatureKind {
             | FeatureKind::Loft { .. }
             | FeatureKind::Sweep { .. }
             | FeatureKind::SurfaceSweep { .. }
+            | FeatureKind::SurfaceLoft { .. }
             | FeatureKind::Import { .. }
             | FeatureKind::MeshImport { .. }
             | FeatureKind::BodyTransfer { .. } => {}