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Pigment bleed between two overlapping wash regions

Source: R/core-watercolor.R
wash_bleed.Rd

Where two wet watercolour washes overlap the pigments diffuse and the colours mix - the "wet-on-wet" bleed. This approximates it without polygon clipping: it samples points lying inside both polygons (the overlap region) and returns soft translucent specks tinted with the blended colour. The grob layer paints the specks at low alpha over the two washes, so the shared area reads as mingled pigment. Pure geometry + colour math; reproduces on every device.

Usage

wash_bleed(
  ax,
  ay,
  bx,
  by,
  col_a,
  col_b,
  density = 0.5,
  bleed = NULL,
  seed = NULL
)

Arguments

ax, ay, bx, by

Vertices (inch space) of the two wash polygons.

col_a, col_b

The two wash colours (any R colour spec).

density

Fraction in [0, 1]: speck density in the overlap. Default 0.5.

bleed

Speck radius scale in inches. NULL (default) scales to ~2.5% of the overlap's bounding diagonal.

seed

Integer seed.

Value

A list(x, y, r, fill) of bleed specks (inch space), or NULL when the polygons' bounding boxes - or the sampled overlap - do not meet.

See also

Other sketch-core: arrowhead(), curve_fill(), engrave_fill(), engrave_ladder(), hachure_fill(), hachure_fill_multi(), leader_path(), repel_layout(), rough_arc(), rough_bezier(), rough_ellipse(), roughen_polyline(), sketch_arrowheads(), sketch_fill(), sketch_fill_multi(), spray_scatter(), stroke_profile(), stroke_ribbon(), treemap_layout(), watercolor_wash(), watercolor_wash_multi()