ConstReadonlyBASE_ALPHA: (_r: number, _g: number, _b: number, a: number) => numberUse only alpha channel.
ReadonlyBASE_BLUE: (_r: number, _g: number, b: number, _a: number) => numberUse only blue channel.
ReadonlyBASE_GREEN: (_r: number, g: number, _b: number, _a: number) => numberUse only green channel.
ReadonlyBASE_RED: (r: number, _g: number, _b: number, _a: number) => numberUse only red channel.
ReadonlyCENTERED_AVERAGE: (r: number, g: number, b: number, _a: number) => numberAverage of RGB components normalized.
ReadonlyINVERTED_AVERAGE: (r: number, g: number, b: number, _a: number) => numberInverted average of RGB components.
Built-in terrain height strategies.