Contact Sets (EnableContactSetsCmd, EnableAllContactCmd, DisableAllContactCmd, ContactSetCmd, contact.edit/list/check): driving a joint stops where bodies of one set would pass through each other (bisection to the touch; penetration found by ray parity and depth on the tessellations); Motion Study (FusionMotionStudyCommand: joint values keyed along a timeline, motion.play, motion.export of occurrence poses per step as JSON or CSV without changing the design, contact-aware); Exploded views (explode.create automatic or by hand, explode.show without changing placements)

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01AS5Tn3xieewUSg3uxrMVdL

crates/doc/src/joints.rs

@@ -148,11 +148,30 @@ pub struct Assembly {
     pub origins: Vec<NamedOrigin>,
     #[serde(default, skip_serializing_if = "Vec::is_empty")]
     pub links: Vec<MotionLink>,
+    #[serde(default, skip_serializing_if = "Vec::is_empty")]
+    pub contact_sets: Vec<crate::motion::ContactSet>,
+    /// Contact sets take effect.
+    #[serde(default, skip_serializing_if = "std::ops::Not::not")]
+    pub contact_enabled: bool,
+    /// Every occurrence is in contact with every other (Enable All Contact).
+    #[serde(default, skip_serializing_if = "std::ops::Not::not")]
+    pub contact_all: bool,
+    #[serde(default, skip_serializing_if = "Vec::is_empty")]
+    pub studies: Vec<crate::motion::MotionStudy>,
+    #[serde(default, skip_serializing_if = "Vec::is_empty")]
+    pub exploded: Vec<crate::motion::ExplodedView>,
 }
 
 impl Assembly {
     pub fn is_empty(&self) -> bool {
-        self.joints.is_empty() && self.origins.is_empty() && self.links.is_empty()
+        self.joints.is_empty()
+            && self.origins.is_empty()
+            && self.links.is_empty()
+            && self.contact_sets.is_empty()
+            && !self.contact_enabled
+            && !self.contact_all
+            && self.studies.is_empty()
+            && self.exploded.is_empty()
     }
 }
 

crates/doc/src/lib.rs

@@ -14,6 +14,7 @@ mod eval;
 pub mod expr;
 pub mod format;
 pub mod joints;
+pub mod motion;
 mod params;
 pub mod plastic;
 pub mod project;

crates/doc/src/motion.rs

@@ -0,0 +1,76 @@
+//! Assembly extras: contact sets (occurrences that stop each other when joints are driven),
+//! motion studies (joint values keyed along a timeline) and exploded views (occurrence moves
+//! shown without changing the design).
+
+use serde::{Deserialize, Serialize};
+use solvecraft_geom::Vec3;
+
+/// Occurrences whose bodies may touch but not pass through each other while joints move.
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
+pub struct ContactSet {
+    pub id: u64,
+    pub name: String,
+    pub occurrences: Vec<u64>,
+    #[serde(default, skip_serializing_if = "std::ops::Not::not")]
+    pub suppressed: bool,
+}
+
+/// One joint value along a motion study: (step, value) points, values in internal units
+/// (radians, mm), linear in between and held before the first and after the last.
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
+pub struct StudyKey {
+    pub joint: u64,
+    #[serde(default)]
+    pub index: usize,
+    pub points: Vec<(f64, f64)>,
+}
+
+impl StudyKey {
+    pub fn value_at(&self, step: f64) -> Option<f64> {
+        let first = self.points.first()?;
+        let last = self.points.last()?;
+        if step <= first.0 {
+            return Some(first.1);
+        }
+        if step >= last.0 {
+            return Some(last.1);
+        }
+        self.points.windows(2).find_map(|w| {
+            let (a, b) = (w.first()?, w.get(1)?);
+            (step >= a.0 && step <= b.0).then(|| if b.0 - a.0 < 1e-12 { b.1 } else { a.1 + (b.1 - a.1) * (step - a.0) / (b.0 - a.0) })
+        })
+    }
+}
+
+/// A motion study: a timeline of `steps` steps along which joints follow their keys.
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
+pub struct MotionStudy {
+    pub id: u64,
+    pub name: String,
+    pub steps: u32,
+    pub keys: Vec<StudyKey>,
+}
+
+/// An exploded view: occurrences moved apart (shown only; the design keeps its placements).
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
+pub struct ExplodedView {
+    pub id: u64,
+    pub name: String,
+    /// (occurrence, world translation)
+    pub moves: Vec<(u64, Vec3)>,
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn keys_interpolate_and_hold() {
+        let k = StudyKey { joint: 1, index: 0, points: vec![(0.0, 0.0), (10.0, 1.0), (20.0, -1.0)] };
+        assert_eq!(k.value_at(-5.0), Some(0.0));
+        assert_eq!(k.value_at(5.0), Some(0.5));
+        assert_eq!(k.value_at(15.0), Some(0.0));
+        assert_eq!(k.value_at(99.0), Some(-1.0));
+        assert_eq!(StudyKey { joint: 1, index: 0, points: vec![] }.value_at(1.0), None);
+    }
+}