scenario

type CartPt struct {
	X float64
	Y float64
}

type CellPoint struct {
	IsoPt
	Z int
}

type IsoPt struct {
	X float64
	Y float64
}

type Scenario struct {

	// All these must be modified by user actions somehow.
	// TODO: extract into the idea of a viewport passed to Update / Draw somehow?
	// Or have a separater Drawer for the Scenario?
	Viewpoint image.Point // Top-left of the screen
	ZIdx      int         // Currently-viewed Z index
	Zoom      float64     // Zoom level to set
	// contains filtered or unexported fields
}