introduce script to generate assembly animation. still needs cleanup

rack/assembly/screwXBarAndYBar.scad

@@ -0,0 +1,42 @@
+include <./common.scad>
+use <./attachXBarWithYBar.scad>
+
+$vpt = [103,90,20];
+$vpr = [68,0,36];
+$vpd = 500;
+$vpf = 22.50;
+
+screwXBarAndYBar(at=$t);
+
+module screwXBarAndYBar(at=0) {
+  screwExtension = lerp(a=16, b=0, t=at);
+
+  // in x bar space
+  function xBarYBarScrewTrans(extension) =
+    translate(v=[27,xBarSideThickness + extension,8]) * rotate(a=[270,0,0]);
+
+  attachXBarWithYBar(at=1);
+
+  multmatrix(xBarSpaceToYBarSpace)
+    union() {
+
+      if (!plasticMask) { xBar(); }
+
+      multmatrix(xBarYBarScrewTrans(screwExtension))
+        caseScrewB();
+
+      multmatrix(xBarMirrorOtherCornerTrans * xBarYBarScrewTrans(screwExtension))
+        caseScrewB();
+    }
+
+  multmatrix(yBarMirrorOtherCornerTrans*xBarSpaceToYBarSpace)
+    union() {
+      if (!plasticMask) { xBar(); }
+
+      multmatrix(xBarYBarScrewTrans(screwExtension))
+        caseScrewB();
+
+      multmatrix(xBarMirrorOtherCornerTrans * xBarYBarScrewTrans(screwExtension))
+        caseScrewB();
+    }
+}