Simple object 3D calculations

    -- Create in 3D
    local sourcePoints = self.points
    local z            = viewScale / ( z - zOffset )
    local leftPoint    = ( xOffset - self.halfWidth + x ) * z
    local rightPoint   = ( xOffset + self.halfWidth + x ) * z

    -- Create the front
    local top        = ( y - self.y - self.height ) * z
    local bottom     = ( y - self.y ) * z