refactor(wire): add WireModel.points_low parallel buffer (empty default)

Foundation for double-single positions: WireModel now carries an
index-paired f32 residual buffer (`points_low`) next to the existing
`points` high half. Empty means "all-zero residual", so every existing
constructor (interactive draw, previews) is unchanged in behaviour;
tessellation from CAD f64 will fill it in the next steps so vertex
precision survives at UTM-scale coordinates.

Co-Authored-By: Claude Opus 4.7 <[email protected]>

src/app/update.rs

@@ -3055,6 +3055,7 @@ impl OpenCADStudio {
                                         [far_neg.x, far_neg.y, far_neg.z],
                                         [far_pos.x, far_pos.y, far_pos.z],
                                     ],
+                                    points_low: Vec::new(),
                                     color: [0.2, 0.7, 0.9, 0.6],
                                     selected: false,
                                     aci: 0,
@@ -3086,6 +3087,7 @@ impl OpenCADStudio {
                                     [far_neg.x, far_neg.y, far_neg.z],
                                     [far_pos.x, far_pos.y, far_pos.z],
                                 ],
+                                points_low: Vec::new(),
                                 color: [0.2, 0.9, 0.5, 0.6],
                                 selected: false,
                                 aci: 0,

src/entities/dimension.rs

@@ -1158,6 +1158,7 @@ fn tessellate_dimension_inner(
                 wires.push(WireModel {
                     name: name.clone(),
                     points: ext1,
+                    points_low: Vec::new(),
                     color: ext_color,
                     selected,
                     aci: 0,
@@ -1177,6 +1178,7 @@ fn tessellate_dimension_inner(
                 wires.push(WireModel {
                     name: name.clone(),
                     points: ext2,
+                    points_low: Vec::new(),
                     color: ext_color,
                     selected,
                     aci: 0,
@@ -1196,6 +1198,7 @@ fn tessellate_dimension_inner(
             wires.push(WireModel {
                 name: name.clone(),
                 points: geom.ext_lines,
+                points_low: Vec::new(),
                 color: ext_color,
                 selected,
                 aci: 0,
@@ -1216,6 +1219,7 @@ fn tessellate_dimension_inner(
     wires.push(WireModel {
         name: name.clone(),
         points: geom.dim_lines,
+        points_low: Vec::new(),
         color: dim_color,
         selected,
         aci: 0,
@@ -1247,6 +1251,7 @@ fn tessellate_dimension_inner(
                 wires.push(WireModel {
                     name: name.clone(),
                     points: vec![],
+                    points_low: Vec::new(),
                     color: fill_color,
                     selected,
                     aci: 0,

src/entities/leader.rs

@@ -603,6 +603,7 @@ impl LeaderTess for Leader {
             return WireModel {
                 name,
                 points: vec![],
+                points_low: Vec::new(),
                 color,
                 selected,
                 aci: 0,
@@ -701,6 +702,7 @@ impl LeaderTess for Leader {
         WireModel {
             name,
             points,
+            points_low: Vec::new(),
             color,
             selected,
             aci: 0,

src/entities/multileader.rs

@@ -1295,6 +1295,7 @@ impl MultiLeaderTess for MultiLeader {
         wires.push(WireModel {
             name: name.clone(),
             points,
+            points_low: Vec::new(),
             color: line_color,
             selected,
             aci: 0,
@@ -1541,6 +1542,7 @@ impl MultiLeaderTess for MultiLeader {
                     wires.push(WireModel {
                         name: name.clone(),
                         points: vec![p0, p1],
+                        points_low: Vec::new(),
                         color: text_color,
                         selected,
                         aci: 0,
@@ -1581,6 +1583,7 @@ impl MultiLeaderTess for MultiLeader {
                     wires.push(WireModel {
                         name: name.clone(),
                         points: vec![],
+                        points_low: Vec::new(),
                         color: text_color,
                         selected,
                         aci: 0,
@@ -1619,6 +1622,7 @@ impl MultiLeaderTess for MultiLeader {
                     wires.push(WireModel {
                         name: name.clone(),
                         points: text_points,
+                        points_low: Vec::new(),
                         color: text_color,
                         selected,
                         aci: 0,
@@ -1676,6 +1680,7 @@ impl MultiLeaderTess for MultiLeader {
                     wires.push(WireModel {
                         name: name.clone(),
                         points: vec![],
+                        points_low: Vec::new(),
                         color: fill_color,
                         selected,
                         aci: 0,
@@ -1704,6 +1709,7 @@ impl MultiLeaderTess for MultiLeader {
                     wires.push(WireModel {
                         name,
                         points: frame_points,
+                        points_low: Vec::new(),
                         color: text_color,
                         selected,
                         aci: 0,

src/entities/table.rs

@@ -702,6 +702,7 @@ pub fn tessellate_table(
             WireModel {
                 name: name.clone(),
                 points,
+                points_low: Vec::new(),
                 color,
                 selected,
                 pattern_length: 0.0,

src/modules/annotate/aligned_dim.rs

@@ -94,6 +94,7 @@ impl CadCommand for AlignedDimensionCommand {
         Some(WireModel {
             name: "dimaligned_preview".into(),
             points: vec![[p1.x, p1.y, p1.z], [p2.x, p2.y, p2.z]],
+            points_low: Vec::new(),
             color: WireModel::CYAN,
             selected: false,
             pattern_length: 0.0,
@@ -134,6 +135,7 @@ fn preview_aligned(p1: Vec3, p2: Vec3, dim_pt: Vec3) -> WireModel {
             [d1.x, d1.y, d1.z],
             [d2.x, d2.y, d2.z],
         ],
+        points_low: Vec::new(),
         color: WireModel::CYAN,
         selected: false,
         pattern_length: 0.0,

src/modules/annotate/angular_dim.rs

@@ -126,6 +126,7 @@ fn preview_wire(points: Vec<Vec3>) -> WireModel {
     WireModel {
         name: "dimangular_preview".to_string(),
         points: points.into_iter().map(|p| [p.x, p.y, p.z]).collect(),
+        points_low: Vec::new(),
         color: WireModel::CYAN,
         selected: false,
         pattern_length: 0.0,

src/modules/annotate/diameter_dim.rs

@@ -97,6 +97,7 @@ fn preview_line(a: Vec3, b: Vec3) -> WireModel {
     WireModel {
         name: "dimdia_preview".into(),
         points: vec![[a.x, a.y, a.z], [b.x, b.y, b.z]],
+        points_low: Vec::new(),
         color: WireModel::CYAN,
         selected: false,
         pattern_length: 0.0,

src/modules/annotate/dim_baseline.rs

@@ -155,6 +155,7 @@ impl CadCommand for DimBaselineCommand {
                 [dim_line_pt.x, dim_line_pt.y, dim_line_pt.z],
                 [dim_line_pt2.x, dim_line_pt2.y, dim_line_pt2.z],
             ],
+            points_low: Vec::new(),
             color: WireModel::CYAN,
             selected: false,
             pattern_length: 0.0,

src/modules/annotate/dim_continue.rs

@@ -135,6 +135,7 @@ impl CadCommand for DimContinueCommand {
                 [dim_line_pt.x, dim_line_pt.y, dim_line_pt.z],
                 [dim_line_pt2.x, dim_line_pt2.y, dim_line_pt2.z],
             ],
+            points_low: Vec::new(),
             color: WireModel::CYAN,
             selected: false,
             pattern_length: 0.0,

src/modules/annotate/dimjogline.rs

@@ -92,6 +92,7 @@ impl CadCommand for DimJogLineCommand {
                 [pt.x + d * 0.3, pt.y, pt.z - d],
                 [pt.x + d, pt.y, pt.z],
             ],
+            points_low: Vec::new(),
             color: WireModel::CYAN,
             selected: false,
             pattern_length: 0.0,

src/modules/annotate/dimtedit.rs

@@ -106,6 +106,7 @@ impl CadCommand for DimTeditCommand {
                 [pt.x - d, pt.y, pt.z + d],
                 [pt.x - d, pt.y, pt.z - d],
             ],
+            points_low: Vec::new(),
             color: WireModel::CYAN,
             selected: false,
             pattern_length: 0.0,

src/modules/annotate/leader_cmd.rs

@@ -165,6 +165,7 @@ fn preview_wire(pts: &[Vec3]) -> WireModel {
     WireModel {
         name: "leader_preview".into(),
         points,
+        points_low: Vec::new(),
         color: WireModel::CYAN,
         selected: false,
         pattern_length: 0.0,

src/modules/annotate/linear_dim.rs

@@ -133,6 +133,7 @@ fn preview_wire(points: Vec<Vec3>) -> WireModel {
     WireModel {
         name: "dimlinear_preview".to_string(),
         points: points.into_iter().map(|p| [p.x, p.y, p.z]).collect(),
+        points_low: Vec::new(),
         color: WireModel::CYAN,
         selected: false,
         pattern_length: 0.0,

src/modules/annotate/mleader_cmd.rs

@@ -151,6 +151,7 @@ fn preview_wire(pts: &[Vec3]) -> WireModel {
     WireModel {
         name: "mleader_preview".into(),
         points,
+        points_low: Vec::new(),
         color: WireModel::CYAN,
         selected: false,
         pattern_length: 0.0,

src/modules/annotate/mleader_edit.rs

@@ -458,6 +458,7 @@ fn preview_wire(pts: &[Vec3]) -> WireModel {
     WireModel {
         name: "mleader_edit_preview".into(),
         points: pts.iter().map(|p| [p.x, p.y, p.z]).collect(),
+        points_low: Vec::new(),
         color: WireModel::CYAN,
         selected: false,
         pattern_length: 0.0,

src/modules/annotate/qdim.rs

@@ -90,6 +90,7 @@ impl CadCommand for QdimCommand {
         Some(WireModel {
             name: "qdim_preview".into(),
             points: vec![[pt.x - d * 3.0, pt.y, pt.z], [pt.x + d * 3.0, pt.y, pt.z]],
+            points_low: Vec::new(),
             color: WireModel::CYAN,
             selected: false,
             pattern_length: 0.0,

src/modules/annotate/radius_dim.rs

@@ -102,6 +102,7 @@ fn preview_wire(points: Vec<Vec3>) -> WireModel {
     WireModel {
         name: "dimradius_preview".to_string(),
         points: points.into_iter().map(|p| [p.x, p.y, p.z]).collect(),
+        points_low: Vec::new(),
         color: WireModel::CYAN,
         selected: false,
         pattern_length: 0.0,

src/modules/annotate/table_cmd.rs

@@ -150,6 +150,7 @@ impl CadCommand for TableCommand {
                     [x, y, z - h],
                     [x, y, z],
                 ],
+                points_low: Vec::new(),
                 color: WireModel::CYAN,
                 selected: false,
                 pattern_length: 0.0,

src/modules/annotate/tolerance_cmd.rs

@@ -92,6 +92,7 @@ impl CadCommand for ToleranceCommand {
                 [pt.x, pt.y, pt.z - d],
                 [pt.x, pt.y, pt.z + d],
             ],
+            points_low: Vec::new(),
             color: WireModel::CYAN,
             selected: false,
             pattern_length: 0.0,

src/modules/draw/draw/attdef.rs

@@ -168,6 +168,7 @@ impl CadCommand for AttdefCommand {
                 [pt.x, pt.y, pt.z - d],
                 [pt.x, pt.y, pt.z + d],
             ],
+            points_low: Vec::new(),
             color: WireModel::CYAN,
             selected: false,
             pattern_length: 0.0,

src/modules/draw/draw/ellipse.rs

@@ -613,6 +613,7 @@ fn line_wire(from: Vec3, to: Vec3) -> WireModel {
     WireModel {
         name: "rubber_band".into(),
         points: vec![[from.x, from.y, from.z], [to.x, to.y, to.z]],
+        points_low: Vec::new(),
         color: WireModel::CYAN,
         selected: false,
         pattern_length: 0.0,

src/modules/draw/draw/line.rs

@@ -78,6 +78,7 @@ impl CadCommand for LineCommand {
         Some(WireModel {
             name: "rubber_band".to_string(),
             points: vec![[last.x, last.y, last.z], [pt.x, pt.y, pt.z]],
+            points_low: Vec::new(),
             color: WireModel::CYAN,
             selected: false,
             pattern_length: 0.0,

src/modules/draw/draw/mline.rs

@@ -133,6 +133,7 @@ impl CadCommand for MlineCommand {
         Some(WireModel {
             name: "mline_preview".into(),
             points: pts,
+            points_low: Vec::new(),
             color: WireModel::CYAN,
             selected: false,
             pattern_length: 0.0,

src/modules/draw/draw/raster_image.rs

@@ -110,6 +110,7 @@ impl CadCommand for ImageCommand {
         Some(WireModel {
             name: "image_preview".into(),
             points: vec![p0, p1, p2, p3, p0],
+            points_low: Vec::new(),
             color: WireModel::CYAN,
             selected: false,
             pattern_length: 0.0,

src/modules/draw/draw/ray.rs

@@ -76,6 +76,7 @@ impl CadCommand for RayCommand {
         Some(WireModel {
             name: "ray_preview".into(),
             points: vec![[base.x, base.y, base.z], [far.x, far.y, far.z]],
+            points_low: Vec::new(),
             color: WireModel::CYAN,
             selected: false,
             pattern_length: 0.0,
@@ -157,6 +158,7 @@ impl CadCommand for XLineCommand {
                 [far_neg.x, far_neg.y, far_neg.z],
                 [far_pos.x, far_pos.y, far_pos.z],
             ],
+            points_low: Vec::new(),
             color: WireModel::CYAN,
             selected: false,
             pattern_length: 0.0,

src/modules/draw/draw/revcloud.rs

@@ -82,6 +82,7 @@ impl CadCommand for RevCloudCommand {
         Some(WireModel {
             name: "revcloud_preview".into(),
             points: preview_pts,
+            points_low: Vec::new(),
             color: WireModel::CYAN,
             selected: false,
             pattern_length: 0.0,

src/modules/draw/draw/wipeout.rs

@@ -122,6 +122,7 @@ impl CadCommand for WipeoutCommand {
                         [min.x, max.y, max.z],
                         [min.x, min.y, min.z],
                     ],
+                    points_low: Vec::new(),
                     color: WireModel::CYAN,
                     selected: false,
                     pattern_length: 0.0,
@@ -148,6 +149,7 @@ impl CadCommand for WipeoutCommand {
                 Some(WireModel {
                     name: "wipeout_poly_preview".into(),
                     points: pts,
+                    points_low: Vec::new(),
                     color: WireModel::CYAN,
                     selected: false,
                     pattern_length: 0.0,

src/modules/draw/inquiry/area.rs

@@ -66,6 +66,7 @@ impl CadCommand for AreaCommand {
         Some(WireModel {
             name: "area_preview".into(),
             points: pts,
+            points_low: Vec::new(),
             color: WireModel::CYAN,
             selected: false,
             pattern_length: 0.0,

src/modules/draw/inquiry/dist.rs

@@ -61,6 +61,7 @@ impl CadCommand for DistCommand {
         Some(WireModel {
             name: "dist_preview".into(),
             points: vec![[p1.x, p1.y, p1.z], [pt.x, pt.y, pt.z]],
+            points_low: Vec::new(),
             color: WireModel::CYAN,
             selected: false,
             pattern_length: 0.0,

src/modules/layout/mview.rs

@@ -88,6 +88,7 @@ impl CadCommand for MviewCommand {
                 [c1.x, pt.y, c1.z],
                 [c1.x, c1.y, c1.z],
             ],
+            points_low: Vec::new(),
             color: WireModel::CYAN,
             selected: false,
             pattern_length: 0.0,

src/modules/model/primitive_cmd.rs

@@ -307,6 +307,7 @@ fn wire(name: &str, points: Vec<[f32; 3]>) -> WireModel {
     WireModel {
         name: name.into(),
         points,
+        points_low: Vec::new(),
         color: WireModel::CYAN,
         selected: false,
         pattern_length: 0.0,

src/modules/view/plot_window.rs

@@ -59,6 +59,7 @@ impl CadCommand for PlotWindowCommand {
                 [p1.x, pt.y, pt.z],
                 [p1.x, p1.y, p1.z],
             ],
+            points_low: Vec::new(),
             color: WireModel::CYAN,
             selected: false,
             pattern_length: 0.0,

src/modules/view/zoom_window.rs

@@ -59,6 +59,7 @@ impl CadCommand for ZoomWindowCommand {
                 [min.x, max.y, 0.0],
                 [min.x, min.y, 0.0],
             ],
+            points_low: Vec::new(),
             color: WireModel::CYAN,
             selected: false,
             pattern_length: 0.0,

src/scene/cache/block_cache.rs

@@ -1106,6 +1106,7 @@ impl Batches {
                 WireModel {
                     name: name.to_string(),
                     points: b.points,
+                    points_low: Vec::new(),
                     color,
                     selected,
                     pattern_length: b.pattern_length,

src/scene/convert/tessellate.rs

@@ -169,6 +169,7 @@ pub fn tessellate(
                     return vec![WireModel {
                         name,
                         points: Vec::new(),
+                        points_low: Vec::new(),
                         color,
                         selected,
                         pattern_length: 0.0,
@@ -207,6 +208,7 @@ pub fn tessellate(
                     out.push(WireModel {
                         name: name.clone(),
                         points: pts,
+                        points_low: Vec::new(),
                         color: wire_color,
                         selected,
                         pattern_length: 0.0,
@@ -248,6 +250,7 @@ pub fn tessellate(
                                 [x, y - s, z],
                                 [x, y + s, z],
                             ],
+                            points_low: Vec::new(),
                             color,
                             selected,
                             pattern_length: 0.0,
@@ -279,6 +282,7 @@ pub fn tessellate(
                     return vec![WireModel {
                         name,
                         points,
+                        points_low: Vec::new(),
                         color,
                         selected,
                         pattern_length,
@@ -308,6 +312,7 @@ pub fn tessellate(
                     return vec![WireModel {
                         name,
                         points,
+                        points_low: Vec::new(),
                         color,
                         selected,
                         pattern_length,
@@ -355,6 +360,7 @@ pub fn tessellate(
                 return vec![WireModel {
                     name,
                     points: local_pts,
+                    points_low: Vec::new(),
                     color,
                     selected,
                     pattern_length: 0.0,
@@ -392,6 +398,7 @@ pub fn tessellate(
                 return vec![WireModel {
                     name,
                     points: local_pts,
+                    points_low: Vec::new(),
                     color,
                     selected,
                     pattern_length,
@@ -432,6 +439,7 @@ pub fn tessellate(
     vec![WireModel {
         name,
         points,
+        points_low: Vec::new(),
         color,
         selected,
         aci: 0,

src/scene/mod.rs

@@ -8196,6 +8196,7 @@ fn tessellate_entity(
         let marker = WireModel {
             name: h.value().to_string(),
             points: vec![],
+            points_low: Vec::new(),
             color: entity_color,
             selected: sel,
             aci: 0,
@@ -8407,6 +8408,7 @@ fn tessellate_entity(
                 return vec![WireModel {
                     name: h.value().to_string(),
                     points: pts,
+                    points_low: Vec::new(),
                     color: entity_color,
                     selected: sel,
                     aci,
@@ -8444,6 +8446,7 @@ fn tessellate_entity(
                 return vec![WireModel {
                     name: h.value().to_string(),
                     points: vec![],
+                    points_low: Vec::new(),
                     color: fill_color,
                     selected: sel,
                     aci,
@@ -8552,6 +8555,7 @@ fn lod_stub_wire(
         // different elevation. 2D entities (text fallbacks) pass
         // z_min = z_max = 0 to keep the historical behaviour.
         points: vec![[ax, ay, z_min], [bx, by, z_max]],
+        points_low: Vec::new(),
         color: stored_color,
         selected,
         aci,
@@ -8607,6 +8611,7 @@ fn lod_stub_wire_3d(
     WireModel {
         name,
         points,
+        points_low: Vec::new(),
         color: stored_color,
         selected,
         aci,

src/scene/model/wire_model.rs

@@ -34,8 +34,14 @@ pub enum TangentGeom {
 pub struct WireModel {
     /// Unique identifier — the handle value as a decimal string.
     pub name: String,
-    /// Ordered world-space positions forming a strip of quads.
+    /// Ordered world-space positions forming a strip of quads. Each entry is
+    /// the "high" half of a double-single f32 pair; [`points_low`] carries the
+    /// matching residual so the shader can reconstruct the f64 source.
     pub points: Vec<[f32; 3]>,
+    /// Low-bit residual paired index-for-index with [`points`]. Empty means
+    /// "all-zero residual" (interactive draw / preview wires whose coordinates
+    /// don't need sub-f32 precision). Tessellation from CAD f64 fills it.
+    pub points_low: Vec<[f32; 3]>,
     /// RGBA colour in [0, 1].
     pub color: [f32; 4],
     /// Whether this wire is currently selected.
@@ -94,6 +100,7 @@ impl WireModel {
         Self {
             name,
             points,
+            points_low: Vec::new(),
             color,
             selected,
             aci: 0,
@@ -216,6 +223,7 @@ impl Default for WireModel {
         Self {
             name: String::new(),
             points: Vec::new(),
+            points_low: Vec::new(),
             color: Self::WHITE,
             selected: false,
             pattern_length: 0.0,

src/scene/text/complex_lt.rs

@@ -210,6 +210,7 @@ pub fn apply_along(
         .map(|pts| WireModel {
             name: name.to_string(),
             points: pts,
+            points_low: Vec::new(),
             color,
             selected,
             pattern_length: 0.0,