feat(polyline): smooth per-segment taper for varying-width wide polylines

A wide polyline with per-vertex varying widths rendered at its widest edge
(uniform-width ones were already exact). Draw the true taper instead.

`WireModel.taper_widths` carries a per-point full band width. The wire
instance (native slim + web fat) gains per-endpoint `world_hw_a/b`, and both
wire shaders interpolate `mix(hw_a, hw_b, which_end)` so each segment's band
narrows/widens linearly — depth-tested, and the linetype dash still applies.

Alignment (widths must match the tessellated points) is solved by building
both together: a new `TruckObject::TaperedLines(points, widths)`, filled by
`common::tapered_band_points` (straight = endpoints, arc = 16 samples with the
width lerped along it). to_truck routes a varying-width polyline here —
LwPolyline before the PLINEGEN split, Polyline2D at its return — while a
uniform-width one keeps the constant-band Contour path unchanged. `world_width`
stays the widest edge as the PDF-stroke + zoom-floor fallback.

Blocks fall back to the constant-widest band (`LocalWire` carries no
taper_widths).

Co-Authored-By: Claude Opus 4.8 <[email protected]>

src/modules/annotate/aligned_dim.rs

@@ -186,6 +186,7 @@ impl CadCommand for AlignedDimensionCommand {
         let p1 = p1.as_vec3();
         let p2 = p2.as_vec3();
         Some(WireModel {
+            taper_widths: Vec::new(),
             world_width: 0.0,
             fill_is_3d: false,
             pick_tris: Vec::new(),
@@ -238,6 +239,7 @@ fn preview_aligned(p1: DVec3, p2: DVec3, dim_pt: DVec3) -> WireModel {
     let d1 = d1.as_vec3();
     let d2 = d2.as_vec3();
     WireModel {
+        taper_widths: Vec::new(),
         world_width: 0.0,
         fill_is_3d: false,
         pick_tris: Vec::new(),

src/modules/annotate/angular_dim.rs

@@ -130,6 +130,7 @@ fn v3(pt: DVec3) -> Vector3 {
 
 fn preview_wire(points: Vec<Vec3>) -> WireModel {
     WireModel {
+        taper_widths: Vec::new(),
         world_width: 0.0,
         fill_is_3d: false,
         pick_tris: Vec::new(),

src/modules/annotate/diameter_dim.rs

@@ -180,6 +180,7 @@ fn v3(p: DVec3) -> Vector3 {
 
 fn preview_line(a: Vec3, b: Vec3) -> WireModel {
     WireModel {
+        taper_widths: Vec::new(),
         world_width: 0.0,
         fill_is_3d: false,
         pick_tris: Vec::new(),

src/modules/annotate/dim_baseline.rs

@@ -179,6 +179,7 @@ impl CadCommand for DimBaselineCommand {
         let dim_line_pt2 = dim_line_pt2.as_vec3();
         let pt = pt.as_vec3();
         Some(WireModel {
+            taper_widths: Vec::new(),
             world_width: 0.0,
             fill_is_3d: false,
             pick_tris: Vec::new(),

src/modules/annotate/dim_continue.rs

@@ -159,6 +159,7 @@ impl CadCommand for DimContinueCommand {
         let dim_line_pt = p1 + perp * (dim_line_perp - p1.dot(perp));
         let dim_line_pt2 = pt + perp * (dim_line_perp - pt.dot(perp));
         Some(WireModel {
+            taper_widths: Vec::new(),
             world_width: 0.0,
             fill_is_3d: false,
             pick_tris: Vec::new(),

src/modules/annotate/dimjogline.rs

@@ -85,6 +85,7 @@ impl CadCommand for DimJogLineCommand {
         }
         let d = 0.3_f32;
         Some(WireModel {
+            taper_widths: Vec::new(),
             world_width: 0.0,
             fill_is_3d: false,
             pick_tris: Vec::new(),

src/modules/annotate/dimtedit.rs

@@ -100,6 +100,7 @@ impl CadCommand for DimTeditCommand {
         }
         let d = 0.2_f32;
         Some(WireModel {
+            taper_widths: Vec::new(),
             world_width: 0.0,
             fill_is_3d: false,
             pick_tris: Vec::new(),

src/modules/annotate/leader_cmd.rs

@@ -163,6 +163,7 @@ fn preview_wire(pts: &[Vec3]) -> WireModel {
         points.push([w2.x, w2.y, w2.z]);
     }
     WireModel {
+        taper_widths: Vec::new(),
         world_width: 0.0,
         fill_is_3d: false,
         pick_tris: Vec::new(),

src/modules/annotate/linear_dim.rs

@@ -218,6 +218,7 @@ fn v3(pt: DVec3) -> Vector3 {
 
 fn preview_wire(points: Vec<DVec3>) -> WireModel {
     WireModel {
+        taper_widths: Vec::new(),
         world_width: 0.0,
         fill_is_3d: false,
         pick_tris: Vec::new(),

src/modules/annotate/mleader_cmd.rs

@@ -150,6 +150,7 @@ fn preview_wire(pts: &[Vec3]) -> WireModel {
         points.push([w2.x, w2.y, w2.z]);
     }
     WireModel {
+        taper_widths: Vec::new(),
         world_width: 0.0,
         fill_is_3d: false,
         pick_tris: Vec::new(),

src/modules/annotate/mleader_edit.rs

@@ -458,6 +458,7 @@ impl CadCommand for MLeaderCollectCommand {
 
 fn preview_wire(pts: &[Vec3]) -> WireModel {
     WireModel {
+        taper_widths: Vec::new(),
         world_width: 0.0,
         fill_is_3d: false,
         pick_tris: Vec::new(),

src/modules/annotate/ordinate_dim.rs

@@ -121,6 +121,7 @@ fn ordinate_elbow(feature: DVec3, leader: DVec3, is_x: bool) -> DVec3 {
 
 fn preview_wire(points: Vec<Vec3>) -> WireModel {
     WireModel {
+        taper_widths: Vec::new(),
         world_width: 0.0,
         fill_is_3d: false,
         pick_tris: Vec::new(),

src/modules/annotate/qdim.rs

@@ -90,6 +90,7 @@ impl CadCommand for QdimCommand {
         }
         let d = 0.5_f32;
         Some(WireModel {
+            taper_widths: Vec::new(),
             world_width: 0.0,
             fill_is_3d: false,
             pick_tris: Vec::new(),

src/modules/annotate/radius_dim.rs

@@ -185,6 +185,7 @@ fn v3(pt: DVec3) -> Vector3 {
 
 fn preview_wire(points: Vec<Vec3>) -> WireModel {
     WireModel {
+        taper_widths: Vec::new(),
         world_width: 0.0,
         fill_is_3d: false,
         pick_tris: Vec::new(),

src/modules/annotate/table_cmd.rs

@@ -139,6 +139,7 @@ impl CadCommand for TableCommand {
             let y = pt.y;
             let z = pt.z;
             Some(WireModel {
+                taper_widths: Vec::new(),
                 world_width: 0.0,
                 fill_is_3d: false,
                 pick_tris: Vec::new(),

src/modules/annotate/tolerance_cmd.rs

@@ -84,6 +84,7 @@ impl CadCommand for ToleranceCommand {
         }
         let d = 0.15_f32;
         Some(WireModel {
+            taper_widths: Vec::new(),
             world_width: 0.0,
             fill_is_3d: false,
             pick_tris: Vec::new(),

src/modules/draw/draw/attdef.rs

@@ -160,6 +160,7 @@ impl CadCommand for AttdefCommand {
         // Show a small cross at the insertion point.
         let d = 0.15_f32;
         Some(WireModel {
+            taper_widths: Vec::new(),
             world_width: 0.0,
             fill_is_3d: false,
             pick_tris: Vec::new(),

src/modules/draw/draw/mline.rs

@@ -136,6 +136,7 @@ impl CadCommand for MlineCommand {
             .collect();
         pts.push([pt.x, pt.y, pt.z]);
         Some(WireModel {
+            taper_widths: Vec::new(),
             world_width: 0.0,
             fill_is_3d: false,
             pick_tris: Vec::new(),

src/modules/draw/draw/raster_image.rs

@@ -108,6 +108,7 @@ impl CadCommand for ImageCommand {
         let p3 = [origin.x, origin.y + world_height, origin.z];
 
         Some(WireModel {
+            taper_widths: Vec::new(),
             world_width: 0.0,
             fill_is_3d: false,
             pick_tris: Vec::new(),

src/modules/draw/draw/ray.rs

@@ -84,6 +84,7 @@ impl CadCommand for RayCommand {
         let dir = (pt - base).normalize_or_zero();
         let far = base + dir * DISPLAY_EXTENT;
         Some(WireModel {
+            taper_widths: Vec::new(),
             world_width: 0.0,
             fill_is_3d: false,
             pick_tris: Vec::new(),
@@ -180,6 +181,7 @@ impl CadCommand for XLineCommand {
         let far_pos = base + dir * DISPLAY_EXTENT;
         let far_neg = base - dir * DISPLAY_EXTENT;
         Some(WireModel {
+            taper_widths: Vec::new(),
             world_width: 0.0,
             fill_is_3d: false,
             pick_tris: Vec::new(),

src/modules/draw/draw/revcloud.rs

@@ -89,6 +89,7 @@ impl CadCommand for RevCloudCommand {
             self.points[0].z as f32,
         ]);
         Some(WireModel {
+            taper_widths: Vec::new(),
             world_width: 0.0,
             fill_is_3d: false,
             pick_tris: Vec::new(),

src/modules/draw/draw/wipeout.rs

@@ -114,6 +114,7 @@ impl CadCommand for WipeoutCommand {
                 let min = p1.min(pt);
                 let max = p1.max(pt);
                 Some(WireModel {
+                    taper_widths: Vec::new(),
                     world_width: 0.0,
                     fill_is_3d: false,
                     pick_tris: Vec::new(),
@@ -161,6 +162,7 @@ impl CadCommand for WipeoutCommand {
                     self.poly_pts[0].z as f32,
                 ]);
                 Some(WireModel {
+                    taper_widths: Vec::new(),
                     world_width: 0.0,
                     fill_is_3d: false,
                     pick_tris: Vec::new(),

src/modules/draw/inquiry/area.rs

@@ -69,6 +69,7 @@ impl CadCommand for AreaCommand {
         pts.push(f(pt));
         pts.push(f(self.points[0]));
         Some(WireModel {
+            taper_widths: Vec::new(),
             world_width: 0.0,
             fill_is_3d: false,
             pick_tris: Vec::new(),

src/modules/draw/inquiry/dist.rs

@@ -63,6 +63,7 @@ impl CadCommand for DistCommand {
         let p1 = self.first?;
         // The preview wire is purely visual, so f32 vertices are fine here.
         Some(WireModel {
+            taper_widths: Vec::new(),
             world_width: 0.0,
             fill_is_3d: false,
             pick_tris: Vec::new(),

src/modules/draw/inquiry/measuregeom.rs

@@ -67,6 +67,7 @@ impl MeasureGeomCommand {
     /// Build a cyan preview wire connecting the picked points and the cursor.
     fn preview_wire(name: &str, pts: Vec<[f32; 3]>) -> WireModel {
         WireModel {
+            taper_widths: Vec::new(),
             world_width: 0.0,
             fill_is_3d: false,
             pick_tris: Vec::new(),

src/modules/draw/modify/trim.rs

@@ -3059,6 +3059,7 @@ fn collect_runs(pts: &[[f64; 2]], take: &dyn Fn([f64; 2]) -> bool, out: &mut Vec
 /// Build a preview wire from a NaN-break point list.
 fn preview_wire(points: Vec<[f32; 3]>, color: [f32; 4], name: &str) -> WireModel {
     WireModel {
+        taper_widths: Vec::new(),
         world_width: 0.0,
         fill_is_3d: false,
         pick_tris: Vec::new(),

src/modules/layout/mview.rs

@@ -81,6 +81,7 @@ impl CadCommand for MviewCommand {
         let pt = pt.as_vec3();
         let c1 = self.corner1?;
         Some(WireModel {
+            taper_widths: Vec::new(),
             world_width: 0.0,
             fill_is_3d: false,
             pick_tris: Vec::new(),

src/modules/model/primitive_cmd.rs

@@ -305,6 +305,7 @@ inventory::submit!(crate::command::CommandRegistration {
 
 fn wire(name: &str, points: Vec<[f32; 3]>) -> WireModel {
     WireModel {
+        taper_widths: Vec::new(),
         world_width: 0.0,
         fill_is_3d: false,
         pick_tris: Vec::new(),

src/modules/view/plot_window.rs

@@ -48,6 +48,7 @@ impl CadCommand for PlotWindowCommand {
         let p1 = self.p1?.as_vec3();
         // Draw the selection rectangle.
         Some(WireModel {
+            taper_widths: Vec::new(),
             world_width: 0.0,
             fill_is_3d: false,
             pick_tris: Vec::new(),

src/modules/view/zoom_window.rs

@@ -65,6 +65,7 @@ impl CadCommand for ZoomWindowCommand {
         let max = p1.max(pt);
         // Draw a rectangle preview
         Some(WireModel {
+            taper_widths: Vec::new(),
             world_width: 0.0,
             fill_is_3d: false,
             pick_tris: Vec::new(),