this rename is absolutely stupid

docs/chapters/pointvectors3d/projection.js

@@ -0,0 +1,35 @@
+/**
+ * A cabinet projection utility
+ */
+
+// 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;
+
+  return {
+    x: offset.x + x + (z / 2) * Math.cos(phi),
+    y: offset.y + y + (z / 2) * Math.sin(phi),
+  };
+}
+
+// and some rebuilt planar projectors
+function projectXY(p, offset, phi) {
+  return project({ x: p.x, y: p.y, z: 0 }, offset, phi);
+}
+
+function projectXZ(p, offset, phi) {
+  return project({ x: p.x, y: 0, z: p.z }, offset, phi);
+}
+
+function projectYZ(p, offset, phi) {
+  return project({ x: 0, y: p.y, z: p.z }, offset, phi);
+}
+
+
+export { project, projectXY, projectXZ, projectYZ }
+