feat(ucs): integrate coordinate systems

Route coordinate input, geometry creation, transforms, properties,\nviews, and viewport persistence through a shared working plane.\n\nRefs #484

src/app/document.rs

@@ -257,11 +257,22 @@ impl DocumentTab {
     /// is identity (plain WCS).
     pub(super) fn model_ucs_from_header(&self) -> Option<Ucs> {
         let h = &self.scene.document.header;
-        let mut u = Ucs::new(h.model_space_ucs_name.clone());
+        let mut u = if h.model_space_ucs_name.is_empty() {
+            Ucs::new("*ACTIVE*")
+        } else {
+            self.scene
+                .document
+                .ucss
+                .get(&h.model_space_ucs_name)
+                .cloned()
+                .unwrap_or_else(|| Ucs::new(h.model_space_ucs_name.clone()))
+        };
         u.origin = h.model_space_ucs_origin;
         u.x_axis = h.model_space_ucs_x_axis;
         u.y_axis = h.model_space_ucs_y_axis;
-        if super::helpers::UcsXform::from_ucs(&u).is_identity() {
+        if h.model_space_ucs_name.is_empty()
+            && super::helpers::UcsXform::from_ucs(&u).is_identity()
+        {
             None
         } else {
             Some(u)
@@ -278,11 +289,21 @@ impl DocumentTab {
         if !vp.ucs_per_viewport {
             return None;
         }
-        let mut u = Ucs::new("*VPUCS*");
+        let mut u = if vp.ucs_handle.is_null() {
+            Ucs::new("*VPUCS*")
+        } else {
+            self.scene
+                .document
+                .ucss
+                .iter()
+                .find(|ucs| ucs.handle == vp.ucs_handle)
+                .cloned()
+                .unwrap_or_else(|| Ucs::new("*VPUCS*"))
+        };
         u.origin = vp.ucs_origin;
         u.x_axis = vp.ucs_x_axis;
         u.y_axis = vp.ucs_y_axis;
-        if super::helpers::UcsXform::from_ucs(&u).is_identity() {
+        if vp.ucs_handle.is_null() && super::helpers::UcsXform::from_ucs(&u).is_identity() {
             None
         } else {
             Some(u)
@@ -369,34 +390,6 @@ impl DocumentTab {
         self.scene.viewcube_ucs = self.ucs_xform().rotation_mat();
     }
 
-    /// UCS→render(wire)-space affine for commands that build axis-aligned
-    /// geometry. Columns are the UCS axes; translation is the UCS origin in wire
-    /// space. Identity outside model space (no UCS there).
-    pub(super) fn ucs_wire_affine(&self) -> glam::Mat4 {
-        if !self.editing_model_space() {
-            return glam::Mat4::IDENTITY;
-        }
-        let (o, x, y, z) = self.ucs_xform().axes();
-        let origin = glam::Vec3::new(o.x as f32, o.y as f32, o.z as f32);
-        glam::Mat4::from_cols(
-            x.as_vec3().extend(0.0),
-            y.as_vec3().extend(0.0),
-            z.as_vec3().extend(0.0),
-            origin.extend(1.0),
-        )
-    }
-
-    /// World-space rotation angle (radians) of the active UCS X axis — the
-    /// default rotation for new text-bearing objects so their text aligns to
-    /// the user's coordinate system. Zero outside model space / with no UCS.
-    pub(super) fn ucs_rotation_angle(&self) -> f64 {
-        if !self.editing_model_space() {
-            return 0.0;
-        }
-        let (_, x, ..) = self.ucs_xform().axes();
-        (x.y as f64).atan2(x.x as f64)
-    }
-
     /// Grid origin (render/wire space) and UCS→world rotation for grid snap and
     /// the grid overlay. Identity / origin-at-zero outside model space.
     pub(super) fn ucs_grid_basis(&self) -> (glam::Vec3, glam::Mat4) {