Masks

Wrap a grob (or list of grobs) as a mask for vl_viewport(mask = ...). The mask content is rendered to an isolated layer; its coverage then modulates the visibility of the viewport's contents.

Usage

as_mask(grob, type = c("alpha", "luminance"))

Arguments

grob

A grob, or a list of grobs, drawn in the masked viewport's coordinate system.

type

"alpha" (default) uses the mask's opacity as coverage; "luminance" uses its brightness (white shows, black hides).

Value

A vellum_mask object.

Examples

as_mask(circle_grob(r = 0.4, gp = vl_gpar(fill = "white", col = NA)))
#> <vellum_mask> type = "alpha", 1 grob