A 2D point defining a corner vertex of a stage zone, in normalized image space (0..1 on both
axes, matching the background art's own pixel grid -- u=0 left edge, v=0 top edge).
Uniform character scale at this corner (default: 1.0). Used for forced-perspective
shrinking as the character "recedes" into the painted background -- see getScaleAt.
A 2D point defining a corner vertex of a stage zone, in normalized image space (0..1 on both axes, matching the background art's own pixel grid -- u=0 left edge, v=0 top edge).