wip for dovetail join for x-y bar

helper/dovetail.scad

@@ -0,0 +1,61 @@
+include <./common.scad>
+
+// centered on z axis
+module dovetail(
+  topWidth,
+  bottomWidth,
+  height,
+  length,
+  headExtension=0,
+  baseExtension=0,
+  frontFaceLength = 0,
+  frontFaceScale = 0,
+  backFaceLength = 0,
+  backFaceScale = 0,
+) {
+
+  translate(v=[0,0,frontFaceLength])
+  linear_extrude(length-(frontFaceLength+backFaceLength))
+  dovetailFace(topWidth,bottomWidth,height,headExtension,baseExtension);
+
+  translate(v=[0,0,frontFaceLength])
+  mirror(v=[0,0,1])
+  linear_extrude(frontFaceLength, scale=[frontFaceScale, frontFaceScale])
+  dovetailFace(topWidth,bottomWidth,height,headExtension,baseExtension);
+
+  translate(v=[0,0,length-backFaceLength])
+  linear_extrude(backFaceLength, scale=[backFaceScale,1])
+  dovetailFace(topWidth,bottomWidth,height,headExtension,baseExtension);
+
+
+
+  module dovetailFace(topWidth, bottomWidth, height, headExtension, baseExtension) {
+
+    union() {
+      // base
+      polygon(points =
+        [[-bottomWidth/2, 0],
+          [-topWidth/2, height],
+          [topWidth/2, height],
+          [bottomWidth/2, 0]]
+      );
+
+      polygon(points =
+        [[-bottomWidth/2, -baseExtension],
+          [-bottomWidth/2,0 ],
+          [bottomWidth/2, 0],
+          [bottomWidth/2, -baseExtension]]
+      );
+
+      translate(v=[0,height])
+      polygon(points =
+        [[-topWidth/2, headExtension],
+          [-topWidth/2,0 ],
+          [topWidth/2, 0],
+          [topWidth/2, headExtension]]
+      );
+    }
+  }
+
+
+}

helper/math.scad

@@ -24,6 +24,7 @@ module mirror4XY(p, dx, dy) {
     children(0);
 }
 
+// TODO: rename to simple align
 module align(a,b) {
 
     rot_axis = cross(a,b);