negative space spar

src/main.rs

@@ -45,8 +45,6 @@ fn main() {
     }
 
     // spars
-    // main wing
-    scad_file.add_object(spar(WINGSPAN+FUSELAGE_GAP*2.0, true));
 
     // "fuselage"
     scad_file.add_object(scad!(Rotate(-90.0, vec3(0.0, 0.0, 1.0));
@@ -100,6 +98,35 @@ fn strut(airfoil: &Airfoil, chord: f32, width: f32) -> ScadObject {
     let aerofoil = scad::PolygonParameters::new(airfoil.get_points().clone());
     let shape = scad!(Polygon(aerofoil));
 
+    let strut_hole = {
+        let points = &airfoil.get_points()[0..80];
+        let perimeter = span_length(points);
+        let span = points_in_range(&Vec::from(points), perimeter * 0.4.. perimeter);
+
+        let mut mask = scad!(Union);
+
+        let mut last: Option<ScadObject> = None;
+        for point in span {
+            let mut current = scad!(Square(vec2(0.001/ chord, CARDBOARD_WIDTH / chord)));
+            current = scad!(Translate2d(point.clone() - vec2(0.0, CARDBOARD_WIDTH/chord)); current);
+            if let Some(last_mask) = last {
+                let mut hull = scad!(Hull);
+                hull.add_child(current.clone());
+                hull.add_child(last_mask);
+                mask.add_child(hull);
+            }
+            last = Some(current);
+        }
+        register_part(mask.clone());
+        mask
+    };
+
+    let mut strut_shape = scad!(Difference);
+    strut_shape.add_child(shape);
+    strut_shape.add_child(strut_hole);
+
+    let shape = strut_shape;
+
     let extrude = LinExtrudeParams {
         height: width,
         center: true,