fix(render): render wide polyline segments as flat 2D rectangles instead of rounded pill shapes

src/scene/pipeline/wire_gpu.rs

@@ -1464,4 +1464,30 @@ mod block_wire_storage_tests {
         };
         assert_eq!(names(&packed), names(&storage));
     }
+
+    #[test]
+    fn wire_shader_validates_with_naga() {
+        let source = include_str!("../../shaders/wire.wgsl");
+        let module = naga::front::wgsl::parse_str(source).expect("wire.wgsl parses cleanly");
+        let mut validator = naga::valid::Validator::new(
+            naga::valid::ValidationFlags::all(),
+            naga::valid::Capabilities::all(),
+        );
+        validator
+            .validate(&module)
+            .expect("wire.wgsl validates cleanly with naga");
+    }
+
+    #[test]
+    fn wire_indexed_shader_validates_with_naga() {
+        let source = include_str!("../../shaders/wire_indexed.wgsl");
+        let module = naga::front::wgsl::parse_str(source).expect("wire_indexed.wgsl parses cleanly");
+        let mut validator = naga::valid::Validator::new(
+            naga::valid::ValidationFlags::all(),
+            naga::valid::Capabilities::all(),
+        );
+        validator
+            .validate(&module)
+            .expect("wire_indexed.wgsl validates cleanly with naga");
+    }
 }

src/shaders/block_wire.wgsl

@@ -144,7 +144,8 @@ fn vs_main(@builtin(vertex_index) vertex_index: u32, in: VertexIn) -> VertexOut
         wire_const.half_width,
     );
     let half_width = mix(half_width_a, half_width_b, which_end);
-    let extension = which_end * 2.0 - 1.0;
+    let is_world = wire_const.world_half_width > 0.0 || in.taper_ratio.x > 0.0 || in.taper_ratio.y > 0.0;
+    let extension = select(which_end * 2.0 - 1.0, 0.0, is_world);
     let offset_px = perpendicular * half_width * side
         + direction * half_width * extension;
     let ndc_offset = offset_px / (u.viewport_size * 0.5);

src/shaders/block_wire_storage.wgsl

@@ -175,7 +175,8 @@ fn vs_main(@builtin(vertex_index) vertex_index: u32, in: VertexIn) -> VertexOut
         wire_const.half_width,
     );
     let half_width = mix(half_width_a, half_width_b, which_end);
-    let extension = which_end * 2.0 - 1.0;
+    let is_world = wire_const.world_half_width > 0.0 || seg_taper_ratio.x > 0.0 || seg_taper_ratio.y > 0.0;
+    let extension = select(which_end * 2.0 - 1.0, 0.0, is_world);
     let offset_px = perpendicular * half_width * side
         + direction * half_width * extension;
     let ndc_offset = offset_px / (u.viewport_size * 0.5);

src/shaders/wire.wgsl

@@ -196,7 +196,11 @@ fn marker_relative(position_high: vec3<f32>, position_low: vec3<f32>, instance:
     // fragment stage round the overhang off: adjoining segments then meet in
     // overlapping round joints, closing the wedge gaps a perpendicular-only
     // expansion leaves on the outside of corners and along tessellated arcs.
-    let ext = which_end * 2.0 - 1.0; // -1 at the A end, +1 at the B end
+    // Wide polylines have physical world-unit width (in.misc.w or in.taper > 0);
+    // in CAD, wide polyline segments are flat/square-ended 2D rectangles (or
+    // trapezoids), not rounded pill shapes.
+    let is_world = in.misc.w > 0.0 || in.taper.x > 0.0 || in.taper.y > 0.0;
+    let ext = select(which_end * 2.0 - 1.0, 0.0, is_world);
     let offset_px = perp * hw * side + dir * hw * ext;
     let ndc_offset = offset_px / (u.viewport_size * 0.5);
     let final_clip = clip_pos + vec4<f32>(ndc_offset * clip_pos.w, 0.0, 0.0);

src/shaders/wire_indexed.wgsl

@@ -165,7 +165,11 @@ fn marker_relative(position_high: vec3<f32>, position_low: vec3<f32>, c: WireCon
     // fragment stage round the overhang off: adjoining segments then meet in
     // overlapping round joints, closing the wedge gaps a perpendicular-only
     // expansion leaves on the outside of corners and along tessellated arcs.
-    let ext = which_end * 2.0 - 1.0; // -1 at the A end, +1 at the B end
+    // Wide polylines have physical world-unit width (world_half_width or taper > 0);
+    // in CAD, wide polyline segments are flat/square-ended 2D rectangles (or
+    // trapezoids), not rounded pill shapes.
+    let is_world = c.world_half_width > 0.0 || in.taper_ratio.x > 0.0 || in.taper_ratio.y > 0.0;
+    let ext = select(which_end * 2.0 - 1.0, 0.0, is_world);
     let offset_px = perp * hw * side + dir * hw * ext;
     let ndc_offset = offset_px / (u.viewport_size * 0.5);
     let final_clip = clip_pos + vec4<f32>(ndc_offset * clip_pos.w, 0.0, 0.0);