Sketch Text (MTextCmd, sketch.edit_text): glyph outlines of the embedded Liberation Sans (SIL OFL 1.1, attributed) as lines and conics that close into extrudable profiles; editable text, height, position and angle

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AS5Tn3xieewUSg3uxrMVdL

ATTRIBUTION.md

@@ -18,6 +18,7 @@ Generated-in-code assets are original and have no file to list:
 | File | Author | Source | Licence |
 |---|---|---|---|
 | docs/screenshots/sample-plate.png | SolveCraft contributors | screenshot of SolveCraft itself (`solvecraft --sample`) | MIT OR Apache-2.0 |
+| crates/sketch/fonts/LiberationSans-Regular.ttf | Red Hat, Inc. (Liberation Fonts 2.x; digitized data Google) | https://github.com/liberationfonts (Debian fonts-liberation), unmodified; licence text in crates/sketch/fonts/OFL.txt; used for sketch Text outlines | SIL OFL 1.1 |
 
 ## Code adapted from sibling projects
 

Cargo.lock

@@ -3235,6 +3235,7 @@ dependencies = [
  "serde_json",
  "solvecraft-geom",
  "thiserror 2.0.21",
+ "ttf-parser",
 ]
 
 [[package]]
@@ -3616,6 +3617,12 @@ dependencies = [
  "truck-geotrait",
 ]
 
+[[package]]
+name = "ttf-parser"
+version = "0.25.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d2df906b07856748fa3f6e0ad0cbaa047052d4a7dd609e231c4f72cee8c36f31"
+
 [[package]]
 name = "type-map"
 version = "0.5.1"

Cargo.toml

@@ -41,6 +41,9 @@ truck-topology = "0.6"
 zip = { version = "3", default-features = false, features = ["deflate"] }
 quick-xml = "0.38"
 
+# fonts (sketch text outlines; MIT OR Apache-2.0, pure Rust)
+ttf-parser = { version = "0.25", default-features = false, features = ["std"] }
+
 # images
 image = { version = "0.25", default-features = false, features = ["png"] }
 

crates/doc/src/project.rs

@@ -136,6 +136,7 @@ pub fn resolve(doc: &Document, vals: &BTreeMap<String, Value>, st: &ModelState,
                 _ => vec![LinkGeom::Point(o)],
             }
         }
+        LinkSource::Text { text, at, height, angle } => solvecraft_sketch::text_geometry(text, *at, *height, *angle)?,
         LinkSource::Plane { name } => {
             let pr =
                 if Plane::named(name).is_some() { PlaneRef::Origin { name: name.clone() } } else { PlaneRef::Construction { name: name.clone() } };

crates/engine/src/cmd/sketch_create.rs

@@ -3,7 +3,7 @@
 
 use serde_json::{Value, json};
 use solvecraft_geom::Vec2;
-use solvecraft_sketch::{ConstraintKind, CurveKind, Sketch};
+use solvecraft_sketch::{ConstraintKind, CurveKind, LinkKind, LinkSource, Sketch};
 
 use super::sketch::{add_c, circumcircle, edit, ids_of, mark_construction, req_parg, result, slot};
 use super::{CommandSpec, in_sketch};
@@ -70,8 +70,75 @@ pub static COMMANDS: &[CommandSpec] =
             .icon("conic")
             .enabled(in_sketch)
             .params("start, end, apex: [x,y] or point refs; rho?: 0…1 (default 0.5: parabola)"),
+        CommandSpec::new("MTextCmd", "Text", text)
+            .at("SKETCH", "CREATE")
+            .icon("text")
+            .enabled(in_sketch)
+            .params("text: string (\\n breaks lines), at: baseline start [x,y], height?: capital height mm (default 5), angle?: deg"),
+        CommandSpec::new("sketch.edit_text", "Edit Text", edit_text)
+            .enabled(in_sketch)
+            .params("link: the text's link id (or entity: one of its curves), text?, at?, height?, angle?: deg"),
     ];
 
+fn text_source(p: &Value, cmd: &str, old: Option<(String, Vec2, f64, f64)>) -> Result<LinkSource> {
+    let (t0, at0, h0, a0) = old.unwrap_or((String::new(), Vec2::ZERO, 5.0, 0.0));
+    let text = str_(p, "text").map(str::to_string).unwrap_or(t0);
+    if text.trim().is_empty() {
+        return Err(bad(cmd, "`text` must not be empty"));
+    }
+    if text.chars().count() > solvecraft_sketch::MAX_TEXT_CHARS {
+        return Err(bad(cmd, "text too long"));
+    }
+    let at = p.get("at").and_then(crate::params::vec2).unwrap_or(at0);
+    let height = num(p, "height").unwrap_or(h0);
+    if !(height > 1e-6 && height < 1e5) {
+        return Err(bad(cmd, "`height` must be positive"));
+    }
+    let angle = num(p, "angle").map(f64::to_radians).unwrap_or(a0);
+    Ok(LinkSource::Text { text, at, height, angle })
+}
+
+fn text(s: &mut Session, p: &Value) -> Result<Value> {
+    let cmd = "MTextCmd";
+    if p.get("at").is_none() {
+        return Err(bad(cmd, "`at` must be the baseline start [x, y]"));
+    }
+    let src = text_source(p, cmd, None)?;
+    let id = s.active_sketch.ok_or_else(|| bad(cmd, "no sketch is being edited"))?;
+    let mut doc = (*s.doc).clone();
+    let mut sk = doc.sketch(id)?.clone();
+    let l = super::sketch_project::add_link(s, &doc, id, &mut sk, LinkKind::Text, src)?;
+    let curves = ids_of(&sk, &sk.link_curves(&l));
+    *doc.sketch_mut(id)? = sk;
+    *s.doc_mut() = doc;
+    Ok(json!({"link": l, "curves": curves}))
+}
+
+fn edit_text(s: &mut Session, p: &Value) -> Result<Value> {
+    let cmd = "sketch.edit_text";
+    let id = s.active_sketch.ok_or_else(|| bad(cmd, "no sketch is being edited"))?;
+    let mut doc = (*s.doc).clone();
+    let mut sk = doc.sketch(id)?.clone();
+    let l = match (str_(p, "link"), str_(p, "entity")) {
+        (Some(l), _) => l.to_string(),
+        (None, Some(e)) => sk.curves.iter().find(|c| c.id == e).and_then(|c| c.link.clone()).ok_or_else(|| bad(cmd, format!("`{e}` is not text")))?,
+        _ => return Err(bad(cmd, "give `link` or `entity`")),
+    };
+    let old = match sk.link(&l).map(|x| (x.kind, x.source.clone())) {
+        Some((LinkKind::Text, LinkSource::Text { text, at, height, angle })) => (text, at, height, angle),
+        _ => return Err(bad(cmd, format!("`{l}` is not text"))),
+    };
+    let src = text_source(p, cmd, Some(old))?;
+    let LinkSource::Text { text, at, height, angle } = &src else { return Err(bad(cmd, "text")) };
+    let geom = solvecraft_sketch::text_geometry(text, *at, *height, *angle)?;
+    sk.set_link_source(&l, src.clone());
+    sk.update_link(&l, &geom)?;
+    let curves = ids_of(&sk, &sk.link_curves(&l));
+    *doc.sketch_mut(id)? = sk;
+    *s.doc_mut() = doc;
+    Ok(json!({"link": l, "curves": curves}))
+}
+
 fn ellipse(s: &mut Session, p: &Value) -> Result<Value> {
     let cmd = "CircleElipse";
     let (c, m) = (req_vec2(cmd, p, "center")?, req_vec2(cmd, p, "major")?);

crates/engine/src/cmd/sketch_modify_tests.rs

@@ -260,3 +260,27 @@ fn ellipse_splines_conic() {
     let r = run(&mut s, "MirrorSketchCommand", json!({"entities": [eid, sid], "line": m}));
     assert_eq!(ids(&r["curves"]).len(), 2);
 }
+
+#[test]
+fn text_makes_profiles_that_extrude_and_edit() {
+    let mut s = new_sketch();
+    let r = run(&mut s, "MTextCmd", json!({"text": "SO", "at": [0, 0], "height": 10}));
+    let link = r["link"].as_str().unwrap().to_string();
+    let a = profiles(&s);
+    // S (one region) + O (ring = outer with a hole, plus the counter as its own region).
+    assert!(a.len() >= 2, "{a:?}");
+    let si = run(&mut s, "sketch.inspect", json!({}));
+    assert_eq!(si["dof"], 0);
+    // Edit the text: the outlines change, the link stays.
+    let r2 = run(&mut s, "sketch.edit_text", json!({"link": link, "text": "I", "height": 20}));
+    assert_eq!(r2["link"], json!(link));
+    let a = profiles(&s);
+    assert_eq!(a.len(), 1, "{a:?}");
+    run(&mut s, "SketchStop", json!({}));
+    run(&mut s, "Extrude", json!({"distance": 2}));
+    let m = run(&mut s, "MeasureCommand", json!({}));
+    let v = m["total"]["volume_mm3"].as_f64().unwrap();
+    // An "I" 20 mm tall is a bar a couple of mm wide.
+    assert!(v > 40.0 && v < 200.0, "{v}");
+    assert!(s.execute("MTextCmd", &json!({"text": "", "at": [0, 0]})).is_err());
+}

crates/engine/src/tests.rs

@@ -281,6 +281,7 @@ fn hostile_params_never_panic() {
         "minor_radius",
         "apex",
         "rho",
+        "text",
     ];
     let mut internal = Vec::new();
     for spec in command_specs() {

crates/engine/src/view.rs

@@ -69,7 +69,7 @@ pub fn grid_step(half_height: f64) -> (f64, f64) {
 pub fn sketch_lines(sk: &Sketch, plane: &Plane, active: bool, determined: &[bool]) -> Vec<(Vec<Vec3>, Rgb, bool)> {
     let mut out = Vec::new();
     for (i, c) in sk.curves.iter().enumerate() {
-        let col = if c.link.is_some() {
+        let col = if c.link.is_some() && !sk.is_text_curve(i) {
             if sk.is_lost_curve(i) { colors::SKETCH_LOST } else { colors::SKETCH_PROJECTED }
         } else if c.construction {
             colors::SKETCH_CONSTRUCTION

crates/sketch/Cargo.toml

@@ -12,6 +12,7 @@ workspace = true
 solvecraft-geom = { workspace = true }
 serde = { workspace = true }
 thiserror = { workspace = true }
+ttf-parser = { workspace = true }
 
 [dev-dependencies]
 serde_json = { workspace = true }

crates/sketch/fonts/OFL.txt

@@ -0,0 +1,97 @@
+Liberation Sans (crates/sketch/fonts/LiberationSans-Regular.ttf)
+
+Digitized data copyright (c) 2010 Google Corporation with Reserved Font Arimo, Tinos and Cousine.
+Copyright (c) 2012 Red Hat, Inc. with Reserved Font Name Liberation.
+
+This Font Software is licensed under the SIL Open Font License, Version 1.1.
+
+SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
+
+PREAMBLE The goals of the Open Font License (OFL) are to stimulate
+worldwide development of collaborative font projects, to support the font
+creation efforts of academic and linguistic communities, and to provide
+a free and open framework in which fonts may be shared and improved in
+partnership with others.
+
+The OFL allows the licensed fonts to be used, studied, modified and
+redistributed freely as long as they are not sold by themselves.
+The fonts, including any derivative works, can be bundled, embedded,
+redistributed and/or sold with any software provided that any reserved
+names are not used by derivative works.  The fonts and derivatives,
+however, cannot be released under any other type of license.  The
+requirement for fonts to remain under this license does not apply to
+any document created using the fonts or their derivatives.
+
+
+
+DEFINITIONS
+"Font Software" refers to the set of files released by the Copyright
+Holder(s) under this license and clearly marked as such.
+This may include source files, build scripts and documentation.
+
+"Reserved Font Name" refers to any names specified as such after the
+copyright statement(s).
+
+"Original Version" refers to the collection of Font Software components
+as distributed by the Copyright Holder(s).
+
+"Modified Version" refers to any derivative made by adding to, deleting,
+or substituting ? in part or in whole ?
+any of the components of the Original Version, by changing formats or
+by porting the Font Software to a new environment.
+
+"Author" refers to any designer, engineer, programmer, technical writer
+or other person who contributed to the Font Software.
+
+
+PERMISSION & CONDITIONS
+
+Permission is hereby granted, free of charge, to any person obtaining a
+copy of the Font Software, to use, study, copy, merge, embed, modify,
+redistribute, and sell modified and unmodified copies of the Font
+Software, subject to the following conditions:
+
+1) Neither the Font Software nor any of its individual components,in
+   Original or Modified Versions, may be sold by itself.
+
+2) Original or Modified Versions of the Font Software may be bundled,
+   redistributed and/or sold with any software, provided that each copy
+   contains the above copyright notice and this license. These can be
+   included either as stand-alone text files, human-readable headers or
+   in the appropriate machine-readable metadata fields within text or
+   binary files as long as those fields can be easily viewed by the user.
+
+3) No Modified Version of the Font Software may use the Reserved Font
+   Name(s) unless explicit written permission is granted by the
+   corresponding Copyright Holder. This restriction only applies to the
+   primary font name as presented to the users.
+
+4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
+   Software shall not be used to promote, endorse or advertise any
+   Modified Version, except to acknowledge the contribution(s) of the
+   Copyright Holder(s) and the Author(s) or with their explicit written
+   permission.
+
+5) The Font Software, modified or unmodified, in part or in whole, must
+   be distributed entirely under this license, and must not be distributed
+   under any other license. The requirement for fonts to remain under
+   this license does not apply to any document created using the Font
+   Software.
+
+
+
+TERMINATION
+This license becomes null and void if any of the above conditions are not met.
+
+
+
+DISCLAIMER
+THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
+OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT.  IN NO EVENT SHALL THE
+COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
+DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM OTHER
+DEALINGS IN THE FONT SOFTWARE.

crates/sketch/src/curves.rs

@@ -34,7 +34,10 @@ pub fn conic_point(a: Vec2, apex: Vec2, b: Vec2, rho: f64, t: f64) -> Vec2 {
 }
 
 pub fn conic_polyline(a: Vec2, apex: Vec2, b: Vec2, rho: f64) -> Vec<Vec2> {
-    let n = SPAN_SAMPLES * 2;
+    // Samples by how far the curve bows from its chord (small text curves need few).
+    let chord = b - a;
+    let bow = chord.cross(apex - a).abs() / chord.len().max(1e-12);
+    let n = ((bow / 2e-3).sqrt().ceil() as usize).clamp(2, SPAN_SAMPLES * 2);
     (0..=n).map(|i| conic_point(a, apex, b, rho, i as f64 / n as f64)).collect()
 }
 

crates/sketch/src/lib.rs

@@ -15,6 +15,7 @@ mod model;
 mod profiles;
 mod shape;
 mod solver;
+mod text;
 
 pub use curves::{MAX_SPLINE_POINTS, conic_point, ellipse_point, spline_end_tangent, spline_polyline};
 pub use link::{Link, LinkGeom, LinkKind, LinkSource, MAX_LINK_ENTITIES};
@@ -22,6 +23,7 @@ pub use model::{Constraint, ConstraintKind, Curve, CurveKind, SPoint, Sketch, Sk
 pub use profiles::{Profile, find_drawn_profiles, find_profiles, merge_regions};
 pub use shape::{Shape, intersections};
 pub use solver::{SolveReport, SolveStatus, solve};
+pub use text::{MAX_TEXT_CHARS, text_geometry};
 
 #[cfg(test)]
 mod tests;

crates/sketch/src/link.rs

@@ -27,6 +27,8 @@ pub enum LinkKind {
     Include,
     /// Section curves of a body or face with the sketch plane.
     Intersect,
+    /// Text outlines (drawn like normal geometry; edit the text to change them).
+    Text,
 }
 
 /// What a link refers to. Model geometry is referenced by a point on it plus the body name and
@@ -53,6 +55,14 @@ pub enum LinkSource {
     /// An origin plane (`XY`, `XZ`, `YZ`) or a construction plane (by name): its trace on the
     /// sketch plane.
     Plane { name: String },
+    /// Text: baseline start `at` (sketch coordinates), capital height and angle (radians).
+    Text {
+        text: String,
+        at: Vec2,
+        height: f64,
+        #[serde(default)]
+        angle: f64,
+    },
 }
 
 impl LinkSource {
@@ -68,6 +78,7 @@ impl LinkSource {
             LinkSource::Origin => "origin".into(),
             LinkSource::Axis { name } => format!("{name} axis"),
             LinkSource::Plane { name } => format!("{name} plane"),
+            LinkSource::Text { text, .. } => format!("text \"{}\"", text.chars().take(20).collect::<String>()),
         }
     }
 }
@@ -96,6 +107,13 @@ pub enum LinkGeom {
         a: Vec2,
         b: Vec2,
     },
+    /// Conic from `a` to `b` with control `apex` (rho 0.5: a quadratic Bézier).
+    Conic {
+        a: Vec2,
+        apex: Vec2,
+        b: Vec2,
+        rho: f64,
+    },
 }
 
 impl LinkGeom {
@@ -106,6 +124,7 @@ impl LinkGeom {
             LinkGeom::Line(a, b) => ok(a) && ok(b) && a.dist(*b) > MERGE_TOL,
             LinkGeom::Circle(c, r) => ok(c) && r.is_finite() && *r > 1e-9 && *r < 1e9,
             LinkGeom::Arc { c, a, b } => ok(c) && ok(a) && ok(b) && c.dist(*a) > 1e-9 && a.dist(*b) > MERGE_TOL,
+            LinkGeom::Conic { a, apex, b, rho } => ok(a) && ok(apex) && ok(b) && a.dist(*b) > MERGE_TOL && *rho > 1e-6 && *rho < 1.0 - 1e-6,
         }
     }
 }
@@ -123,6 +142,7 @@ enum LCurve {
     Line(usize, usize),
     Circle(usize, f64),
     Arc(usize, usize, usize),
+    Conic(usize, usize, usize, f64),
 }
 
 fn layout(geom: &[LinkGeom]) -> Result<Layout> {
@@ -163,6 +183,12 @@ fn layout(geom: &[LinkGeom]) -> Result<Layout> {
                     l.curves.push(LCurve::Arc(c, a, b));
                 }
             }
+            LinkGeom::Conic { a, apex, b, rho } => {
+                let (a, b, x) = (pt(&mut l.pts, a), pt(&mut l.pts, b), pt(&mut l.pts, apex));
+                if a != b && x != a && x != b {
+                    l.curves.push(LCurve::Conic(a, b, x, rho));
+                }
+            }
         }
     }
     // Lone points that a curve also uses are not lone.
@@ -171,6 +197,7 @@ fn layout(geom: &[LinkGeom]) -> Result<Layout> {
             LCurve::Line(a, b) => a == i || b == i,
             LCurve::Circle(c, _) => c == i,
             LCurve::Arc(c, a, b) => c == i || a == i || b == i,
+            LCurve::Conic(a, b, x, _) => a == i || b == i || x == i,
         })
     };
     let curves = l.curves.clone();
@@ -179,7 +206,13 @@ fn layout(geom: &[LinkGeom]) -> Result<Layout> {
 }
 
 fn same_shape(a: &LCurve, b: &LCurve) -> bool {
-    matches!((a, b), (LCurve::Line(..), LCurve::Line(..)) | (LCurve::Circle(..), LCurve::Circle(..)) | (LCurve::Arc(..), LCurve::Arc(..)))
+    matches!(
+        (a, b),
+        (LCurve::Line(..), LCurve::Line(..))
+            | (LCurve::Circle(..), LCurve::Circle(..))
+            | (LCurve::Arc(..), LCurve::Arc(..))
+            | (LCurve::Conic(..), LCurve::Conic(..))
+    )
 }
 
 impl Sketch {
@@ -202,6 +235,11 @@ impl Sketch {
         self.curves.get(ci).is_some_and(|c| c.link.is_some())
     }
 
+    /// Is this curve text outline (linked, but drawn like normal geometry)?
+    pub fn is_text_curve(&self, ci: usize) -> bool {
+        self.curves.get(ci).and_then(|c| c.link.as_deref()).and_then(|l| self.link(l)).is_some_and(|l| l.kind == LinkKind::Text)
+    }
+
     /// Is the curve's link lost (its reference no longer found)?
     pub fn is_lost_curve(&self, ci: usize) -> bool {
         self.curves.get(ci).and_then(|c| c.link.as_deref()).and_then(|l| self.link(l)).is_some_and(|l| l.lost)
@@ -245,6 +283,7 @@ impl Sketch {
                 LCurve::Line(a, b) => (CurveKind::Line { a: point(self, a)?, b: point(self, b)? }, "l"),
                 LCurve::Circle(c, r) => (CurveKind::Circle { c: point(self, c)?, r }, "c"),
                 LCurve::Arc(c, a, b) => (CurveKind::Arc { c: point(self, c)?, a: point(self, a)?, b: point(self, b)? }, "a"),
+                LCurve::Conic(a, b, x, rho) => (CurveKind::Conic { a: point(self, a)?, b: point(self, b)?, apex: point(self, x)?, rho }, "k"),
             };
             let cid = self.fresh(prefix);
             self.curves.push(Curve { id: cid, kind, construction: false, reversed: false, link: Some(id.to_string()) });
@@ -274,6 +313,7 @@ impl Sketch {
                 Some(CurveKind::Line { a, b }) => Some(LCurve::Line(local(*a)?, local(*b)?)),
                 Some(CurveKind::Circle { c, r }) => Some(LCurve::Circle(local(*c)?, *r)),
                 Some(CurveKind::Arc { c, a, b }) => Some(LCurve::Arc(local(*c)?, local(*a)?, local(*b)?)),
+                Some(CurveKind::Conic { a, b, apex, rho }) => Some(LCurve::Conic(local(*a)?, local(*b)?, local(*apex)?, *rho)),
                 _ => None,
             })
             .collect();
@@ -297,6 +337,11 @@ impl Sketch {
                     visit(a);
                     visit(b);
                 }
+                LCurve::Conic(a, b, x, _) => {
+                    visit(a);
+                    visit(b);
+                    visit(x);
+                }
             }
         }
         for i in &lay.lone {
@@ -310,6 +355,7 @@ impl Sketch {
                 LCurve::Line(a, b) => LCurve::Line(renum(a), renum(b)),
                 LCurve::Circle(c, r) => LCurve::Circle(renum(c), r),
                 LCurve::Arc(c, a, b) => LCurve::Arc(renum(c), renum(a), renum(b)),
+                LCurve::Conic(a, b, x, r) => LCurve::Conic(renum(a), renum(b), renum(x), r),
             })
             .collect();
         let same = match &cur {
@@ -322,6 +368,7 @@ impl Sketch {
                                 (LCurve::Line(a0, a1), LCurve::Line(b0, b1)) => a0 == b0 && a1 == b1,
                                 (LCurve::Circle(a0, _), LCurve::Circle(b0, _)) => a0 == b0,
                                 (LCurve::Arc(a0, a1, a2), LCurve::Arc(b0, b1, b2)) => a0 == b0 && a1 == b1 && a2 == b2,
+                                (LCurve::Conic(a0, a1, a2, _), LCurve::Conic(b0, b1, b2, _)) => a0 == b0 && a1 == b1 && a2 == b2,
                                 _ => false,
                             }
                     })
@@ -342,6 +389,9 @@ impl Sketch {
                 if let (LCurve::Circle(_, r), Some(Curve { kind: CurveKind::Circle { r: slot, .. }, .. })) = (c, self.curves.get_mut(*ci)) {
                     *slot = *r;
                 }
+                if let (LCurve::Conic(.., r), Some(Curve { kind: CurveKind::Conic { rho, .. }, .. })) = (c, self.curves.get_mut(*ci)) {
+                    *rho = *r;
+                }
             }
             return Ok(false);
         }

crates/sketch/src/text.rs

@@ -0,0 +1,129 @@
+//! Sketch text: glyph outlines of an embedded open font (Liberation Sans, SIL OFL 1.1; see
+//! `fonts/OFL.txt` and ATTRIBUTION.md) as lines and conics (TrueType quadratic Béziers are
+//! conics with rho = 0.5), so text closes into profiles that can be extruded.
+
+use solvecraft_geom::Vec2;
+
+use crate::link::LinkGeom;
+use crate::model::{Result, SketchError};
+
+static FONT: &[u8] = include_bytes!("../fonts/LiberationSans-Regular.ttf");
+
+/// Most characters in one text.
+pub const MAX_TEXT_CHARS: usize = 1000;
+
+struct Outline {
+    out: Vec<LinkGeom>,
+    start: Vec2,
+    cur: Vec2,
+    map: Box<dyn Fn(f32, f32) -> Vec2>,
+}
+
+impl Outline {
+    fn line(&mut self, to: Vec2) {
+        if self.cur.dist(to) > 1e-9 {
+            self.out.push(LinkGeom::Line(self.cur, to));
+        }
+        self.cur = to;
+    }
+    fn quad(&mut self, apex: Vec2, to: Vec2) {
+        let (a, b) = (self.cur, to);
+        let chord = b - a;
+        let off = chord.cross(apex - a).abs() / chord.len().max(1e-12);
+        if off < 1e-6 || a.dist(b) < 1e-9 {
+            self.line(to);
+            return;
+        }
+        self.out.push(LinkGeom::Conic { a, apex, b, rho: 0.5 });
+        self.cur = to;
+    }
+}
+
+impl ttf_parser::OutlineBuilder for Outline {
+    fn move_to(&mut self, x: f32, y: f32) {
+        let p = (self.map)(x, y);
+        self.start = p;
+        self.cur = p;
+    }
+    fn line_to(&mut self, x: f32, y: f32) {
+        let p = (self.map)(x, y);
+        self.line(p);
+    }
+    fn quad_to(&mut self, x1: f32, y1: f32, x: f32, y: f32) {
+        let (c, p) = ((self.map)(x1, y1), (self.map)(x, y));
+        self.quad(c, p);
+    }
+    fn curve_to(&mut self, x1: f32, y1: f32, x2: f32, y2: f32, x: f32, y: f32) {
+        // A cubic as two quadratics (split at the middle).
+        let (p0, c1, c2, p3) = (self.cur, (self.map)(x1, y1), (self.map)(x2, y2), (self.map)(x, y));
+        let mid = (p0 + c1 * 3.0 + c2 * 3.0 + p3) / 8.0;
+        let q1 = p0 + (c1 - p0) * 0.75;
+        let q2 = p3 + (c2 - p3) * 0.75;
+        self.quad(q1, mid);
+        self.quad(q2, p3);
+    }
+    fn close(&mut self) {
+        let s = self.start;
+        self.line(s);
+    }
+}
+
+/// Outline geometry of `text` with its baseline starting at `at`, capital height `height`
+/// (mm), rotated by `angle` (radians) about `at`. Lines break at `\n`.
+pub fn text_geometry(text: &str, at: Vec2, height: f64, angle: f64) -> Result<Vec<LinkGeom>> {
+    if text.chars().count() > MAX_TEXT_CHARS {
+        return Err(SketchError::TooLarge);
+    }
+    if !(height.is_finite() && height > 1e-6 && height < 1e6) || !angle.is_finite() || !at.is_finite() {
+        return Err(SketchError::Invalid("text height must be positive".into()));
+    }
+    let face = ttf_parser::Face::parse(FONT, 0).map_err(|e| SketchError::Invalid(format!("font: {e}")))?;
+    let cap = face.capital_height().map(f64::from).filter(|c| *c > 0.0).unwrap_or(f64::from(face.units_per_em()) * 0.7);
+    let k = height / cap;
+    let line_gap = f64::from(face.ascender() - face.descender() + face.line_gap()) * k;
+    let (s, c) = angle.sin_cos();
+    let mut out = Vec::new();
+    for (row, line) in text.split('\n').enumerate() {
+        let mut pen = 0.0f64;
+        let base_y = -(row as f64) * line_gap;
+        for ch in line.chars() {
+            let Some(gid) = face.glyph_index(ch).or_else(|| face.glyph_index('?')) else { continue };
+            let x0 = pen;
+            let map = Box::new(move |x: f32, y: f32| {
+                let (lx, ly) = (x0 + f64::from(x) * k, base_y + f64::from(y) * k);
+                at + Vec2::new(lx * c - ly * s, lx * s + ly * c)
+            });
+            let mut ob = Outline { out: Vec::new(), start: at, cur: at, map };
+            let _ = face.outline_glyph(gid, &mut ob);
+            out.extend(ob.out);
+            pen += f64::from(face.glyph_hor_advance(gid).unwrap_or(0)) * k;
+        }
+    }
+    Ok(out)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn letters_have_closed_outlines_at_the_cap_height() {
+        let g = text_geometry("HO", Vec2::new(5.0, 0.0), 10.0, 0.0).unwrap();
+        assert!(!g.is_empty());
+        let ys: Vec<f64> = g
+            .iter()
+            .flat_map(|x| match *x {
+                LinkGeom::Line(a, b) => vec![a.y, b.y],
+                LinkGeom::Conic { a, b, .. } => vec![a.y, b.y],
+                _ => vec![],
+            })
+            .collect();
+        let top = ys.iter().cloned().fold(f64::MIN, f64::max);
+        assert!((top - 10.0).abs() < 0.3, "{top}");
+        assert!(g.iter().any(|x| matches!(x, LinkGeom::Conic { .. })), "O has curves");
+        assert!(text_geometry("x", Vec2::ZERO, -1.0, 0.0).is_err());
+        assert!(text_geometry(&"x".repeat(2000), Vec2::ZERO, 1.0, 0.0).is_err());
+        // Empty text makes nothing (not an error here; the command rejects it).
+        assert!(text_geometry("", Vec2::ZERO, 1.0, 0.0).unwrap().is_empty());
+    }
+}

docs/parity.md

@@ -2,7 +2,7 @@
 
 Generated by `cargo xtask parity` from `xtask/data/fusion-catalog.tsv` (the toolbar commands of Fusion's Design workspace, ids and names only) and the live command registry (`solvecraft-cli commands`). A command counts as live when SolveCraft registers the same command id. This measures breadth, not depth; see ROADMAP.md and docs/oracle.md for depth.
 
-**SOLID + SKETCH: 89 / 291 commands live (31%).** All Design tabs: 182 / 1175 (15%). Registered commands: 115.
+**SOLID + SKETCH: 90 / 291 commands live (31%).** All Design tabs: 183 / 1175 (16%). Registered commands: 117.
 
 | Tab | Panel | Live | Total | % |
 |---|---|---:|---:|---:|
@@ -15,7 +15,7 @@ Generated by `cargo xtask parity` from `xtask/data/fusion-catalog.tsv` (the tool
 | SOLID | INSERT | 1 | 11 | 9% |
 | SOLID | SELECT | 0 | 15 | 0% |
 | SOLID | POSITION | 0 | 2 | 0% |
-| SKETCH | CREATE | 34 | 41 | 83% |
+| SKETCH | CREATE | 35 | 41 | 85% |
 | SKETCH | MODIFY | 11 | 12 | 92% |
 | SKETCH | CONSTRAINTS | 11 | 15 | 73% |
 | SKETCH | CONFIGURE | 0 | 3 | 0% |
@@ -158,6 +158,7 @@ Generated by `cargo xtask parity` from `xtask/data/fusion-catalog.tsv` (the tool
 - SKETCH › CREATE › Control Point Spline (`DrawCVMSpline5D`)
 - SKETCH › CREATE › Conic Curve (`ConicCurveCmd`)
 - SKETCH › CREATE › Point (`DrawPoint`)
+- SKETCH › CREATE › Text (`MTextCmd`)
 - SKETCH › CREATE › Mirror (`MirrorSketchCommand`)
 - SKETCH › CREATE › Circular Pattern (`CircularSketchPatternCommand`)
 - SKETCH › CREATE › Rectangular Pattern (`RectangularSketchPatternCommand`)
@@ -330,7 +331,6 @@ Generated by `cargo xtask parity` from `xtask/data/fusion-catalog.tsv` (the tool
 - SOLID › POSITION › Capture Position (`SnapshotCmd`)
 - SOLID › POSITION › Revert Position (`AsBuiltPositionsCmd`)
 - SKETCH › CREATE › SketchConstrainer (`SketchConstrainer`)
-- SKETCH › CREATE › Text (`MTextCmd`)
 - SKETCH › CREATE › Fit Curves to Mesh Section (`FitCurvesToSectionCommand`)
 - SKETCH › CREATE › Spun Profile (`SpunProfileCmd`)
 - SKETCH › CREATE › Project To Surface (`ProjectToSurface`)