full regeneration

docs/chapters/pointvectors3d/projection.js

@@ -1,23 +1,25 @@
 /**
- * A cabinet projection utility
+ * A cabinet projection utility library
  */
 
-// Universal projector function
+// Universal projector function:
+
 function project(point3d, offset = { x: 0, y: 0 }, phi = -Math.PI / 6) {
   // what they rarely tell you: if you want Z to "go up",
   // X to "come out of the screen", and Y to be the "left/right",
   // we need to switch some coordinates around:
-  const x = point3d.y,
-    y = -point3d.z,
-    z = -point3d.x;
+  const a = point3d.y,
+    b = -point3d.z,
+    c = -point3d.x / 2;
 
   return {
-    x: offset.x + x + (z / 2) * Math.cos(phi),
-    y: offset.y + y + (z / 2) * Math.sin(phi),
+    x: offset.x + a + c * Math.cos(phi),
+    y: offset.y + b + c * Math.sin(phi),
   };
 }
 
-// and some rebuilt planar projectors
+// and some planar projectors:
+
 function projectXY(p, offset, phi) {
   return project({ x: p.x, y: p.y, z: 0 }, offset, phi);
 }
@@ -30,6 +32,4 @@ function projectYZ(p, offset, phi) {
   return project({ x: 0, y: p.y, z: p.z }, offset, phi);
 }
 
-
-export { project, projectXY, projectXZ, projectYZ }
-
+export { project, projectXY, projectXZ, projectYZ };