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Cube viewer invariants

The cube coordinate convention (the invariant)

All cube-attached features use the same coordinate convention. This is the single most important rule for avoiding frustration.

  • The cube is centered at the origin of its transform space.
  • Cube edge length is S = var(--cd-cube-size) (fallback --cube-size).
  • Half size is H = 0.5 * S.

We refer to corners using front/back, left/right, bottom/top.

  • Front is the face closest to the viewer at the default view.
  • Back is the opposite face.
  • Left/Right are from the viewer’s perspective at the default view.
  • Bottom/Top are vertical.

Axis rig placement

We anchor axes at two corners:

  • Origin XY = front-bottom-left corner
  • Origin T = front-bottom-right corner

Axis directions:

  • Longitude (X axis): along the front-bottom edge, left → right
  • Latitude (Y axis): along the front-left edge, bottom → top
  • Time (T axis): along the bottom-right edge, front → back (“depth”)

Time ordering:

  • Newest time (tN) is at the front where time meets the longitude corner.
  • Oldest time (t0) is at the back end of the time axis.

If you change these conventions, update all axis placement math and tick placement logic together.