Sweep: orientation, twist and end scale (#1269)

Part of #771 and #772. solid.sweep and surface.sweep take orientation (perpendicular, parallel or a direction), twist (up to 4 turns) and end scale (0.01 to 100), applied about the profile's normal through the path's start; default options run the old sweep, so existing sweeps are unchanged. New fields are optional, left out when unset and noted under format 21; twist and scale are model parameters. Both sweep dialogs get Orientation, Twist and End Scale rows; labels in every catalog. Checked on main + this branch: cargo check --workspace, kernel/engine/UI sweep tests, the doc suite and the robustness goldens.

crates/doc/src/document.rs

@@ -262,6 +262,26 @@ pub struct ThinWall {
     pub thickness2: Option<String>,
 }
 
+/// How a swept profile turns as it follows its path.
+#[derive(Clone, Copy, Debug, Default, PartialEq, Serialize, Deserialize, solidcraft_derive::Walk)]
+#[serde(rename_all = "snake_case")]
+pub enum SweepOrientation {
+    /// Square to the path, turning with it (a rotation-minimising frame).
+    #[default]
+    Perpendicular,
+    /// As drawn: the profile moves along the path without turning.
+    Parallel,
+    /// Square to the path, its turn about the path fixed by this direction (in the feature's
+    /// frame): the direction's projection onto the profile stays where it was at the start.
+    Direction(#[walk(dir)] Vec3),
+}
+
+impl SweepOrientation {
+    pub fn is_perpendicular(&self) -> bool {
+        *self == SweepOrientation::Perpendicular
+    }
+}
+
 /// Where a thin wall lies against its curves. A closed loop's inside is the area it encloses;
 /// an open chain's is the side it bends toward (a straight one's, the left of its first
 /// curve as drawn).
@@ -701,6 +721,17 @@ pub enum FeatureKind {
         #[walk(sketch)]
         path_sketch: u64,
         path: Vec<String>,
+        /// How the profile turns along the path (default: perpendicular to it).
+        #[serde(default, skip_serializing_if = "SweepOrientation::is_perpendicular")]
+        orientation: SweepOrientation,
+        /// Angle the profile turns about the path over its length.
+        #[serde(default, skip_serializing_if = "Option::is_none")]
+        #[walk(angle = "Twist")]
+        twist: Option<String>,
+        /// The profile's scale at the end of the path (linear along its length).
+        #[serde(default, skip_serializing_if = "Option::is_none")]
+        #[walk(unitless = "Scale")]
+        scale: Option<String>,
         #[serde(default)]
         operation: Operation,
         #[serde(default, skip_serializing_if = "Vec::is_empty")]
@@ -1327,6 +1358,17 @@ pub enum FeatureKind {
         #[walk(sketch)]
         path_sketch: u64,
         path: Vec<String>,
+        /// How the profile turns along the path (default: perpendicular to it).
+        #[serde(default, skip_serializing_if = "SweepOrientation::is_perpendicular")]
+        orientation: SweepOrientation,
+        /// Angle the profile turns about the path over its length.
+        #[serde(default, skip_serializing_if = "Option::is_none")]
+        #[walk(angle = "Twist")]
+        twist: Option<String>,
+        /// The profile's scale at the end of the path (linear along its length).
+        #[serde(default, skip_serializing_if = "Option::is_none")]
+        #[walk(unitless = "Scale")]
+        scale: Option<String>,
     },
     /// A surface body lofted through sections in order, each one open or closed chain of
     /// sketch curves: walls only, no caps.