Tweak a brush specification

Usage

tweak_brush(
  brush,
  normalize = "all",
  opaque,
  opaque_multiply,
  opaque_linearize,
  radius_logarithmic,
  hardness,
  anti_aliasing,
  dabs_per_basic_radius,
  dabs_per_actual_radius,
  dabs_per_second,
  radius_by_random,
  speed1_slowness,
  speed2_slowness,
  speed1_gamma,
  speed2_gamma,
  offset_by_random,
  offset_by_speed,
  offset_by_speed_slowness,
  slow_tracking,
  slow_tracking_per_dab,
  tracking_noise,
  color_h,
  color_s,
  color_v,
  restore_color,
  change_color_h,
  change_color_l,
  change_color_hsl_s,
  change_color_v,
  change_color_hsv_s,
  smudge,
  smudge_length,
  smudge_radius_log,
  eraser,
  stroke_threshold,
  stroke_duration_logarithmic,
  stroke_holdtime,
  custom_input,
  custom_input_slowness,
  elliptical_dab_ratio,
  elliptical_dab_angle,
  direction_filter,
  lock_alpha,
  colorize,
  snap_to_pixel,
  pressure_gain_log,
  gridmap_scale,
  gridmap_scale_x,
  gridmap_scale_y,
  smudge_length_log,
  smudge_bucket,
  smudge_transparency,
  offset_y,
  offset_x,
  offset_angle,
  offset_angle_asc,
  offset_angle_view,
  offset_angle_2,
  offset_angle_2_asc,
  offset_angle_2_view,
  offset_angle_adj,
  offset_multiplier,
  posterize,
  posterize_num,
  paint_mode
)

Arguments

brush: Installed brush name, .myb file path, JSON brush string, or another tweak_brush() object.
normalize: One of "all", "size", "tracking", or "none".
opaque: 0 means brush is transparent, 1 fully visible (also known as alpha or opacity)
opaque_multiply: This gets multiplied with opaque. You should only change the pressure input of this setting. Use 'opaque' instead to make opacity depend on speed. This setting is responsible to stop painting when there is zero pressure. This is just a convention, the behaviour is identical to 'opaque'.
opaque_linearize: Correct the nonlinearity introduced by blending multiple dabs on top of each other. This correction should get you a linear ("natural") pressure response when pressure is mapped to opaque_multiply, as it is usually done. 0.9 is good for standard strokes, set it smaller if your brush scatters a lot, or higher if you use dabs_per_second. 0.0 the opaque value above is for the individual dabs 1.0 the opaque value above is for the final brush stroke, assuming each pixel gets (dabs_per_radius*2) brushdabs on average during a stroke
radius_logarithmic: Basic brush radius (logarithmic) 0.7 means 2 pixels 3.0 means 20 pixels
hardness: Hard brush-circle borders (setting to zero will draw nothing). To reach the maximum hardness, you need to disable Pixel feather.
anti_aliasing: This setting decreases the hardness when necessary to prevent a pixel staircase effect (aliasing) by making the dab more blurred. 0.0 disable (for very strong erasers and pixel brushes) 1.0 blur one pixel (good value) 5.0 notable blur, thin strokes will disappear
dabs_per_basic_radius: How many dabs to draw while the pointer moves a distance of one brush radius (more precise: the base value of the radius)
dabs_per_actual_radius: Same as above, but the radius actually drawn is used, which can change dynamically
dabs_per_second: Dabs to draw each second, no matter how far the pointer moves
radius_by_random: Alter the radius randomly each dab. You can also do this with the by_random input on the radius setting. If you do it here, there are two differences: 1) the opaque value will be corrected such that a big-radius dabs is more transparent 2) it will not change the actual radius seen by dabs_per_actual_radius
speed1_slowness: How slow the input fine speed is following the real speed 0.0 change immediately as your speed changes (not recommended, but try it)
speed2_slowness: Same as 'fine speed filter', but note that the range is different
speed1_gamma: This changes the reaction of the 'fine speed' input to extreme physical speed. You will see the difference best if 'fine speed' is mapped to the radius. -8.0 very fast speed does not increase 'fine speed' much more +8.0 very fast speed increases 'fine speed' a lot For very slow speed the opposite happens.
speed2_gamma: Same as 'fine speed gamma' for gross speed
offset_by_random: Add a random offset to the position where each dab is drawn 0.0 disabled 1.0 standard deviation is one basic radius away <0.0 negative values produce no jitter
offset_by_speed: Change position depending on pointer speed = 0 disable > 0 draw where the pointer moves to < 0 draw where the pointer comes from
offset_by_speed_slowness: How slow the offset goes back to zero when the cursor stops moving
slow_tracking: Slowdown pointer tracking speed. 0 disables it, higher values remove more jitter in cursor movements. Useful for drawing smooth, comic-like outlines.
slow_tracking_per_dab: Similar as above but at brushdab level (ignoring how much time has passed if brushdabs do not depend on time)
tracking_noise: Add randomness to the mouse pointer; this usually generates many small lines in random directions; maybe try this together with 'slow tracking'
color_h: Color hue
color_s: Color saturation
color_v: Color value (brightness, intensity)
restore_color: When selecting a brush, the color can be restored to the color that the brush was saved with. 0.0 do not modify the active color when selecting this brush 0.5 change active color towards brush color 1.0 set the active color to the brush color when selected
change_color_h: Change color hue. -0.1 small clockwise color hue shift 0.0 disable 0.5 counterclockwise hue shift by 180 degrees
change_color_l: Change the color lightness using the HSL color model. -1.0 blacker 0.0 disable 1.0 whiter
change_color_hsl_s: Change the color saturation using the HSL color model. -1.0 more grayish 0.0 disable 1.0 more saturated
change_color_v: Change the color value (brightness, intensity) using the HSV color model. HSV changes are applied before HSL. -1.0 darker 0.0 disable 1.0 brigher
change_color_hsv_s: Change the color saturation using the HSV color model. HSV changes are applied before HSL. -1.0 more grayish 0.0 disable 1.0 more saturated
smudge: Paint with the smudge color instead of the brush color. The smudge color is slowly changed to the color you are painting on. 0.0 do not use the smudge color 0.5 mix the smudge color with the brush color 1.0 use only the smudge color
smudge_length: This controls how fast the smudge color becomes the color you are painting on. 0.0 immediately update the smudge color (requires more CPU cycles because of the frequent color checks) 0.5 change the smudge color steadily towards the canvas color 1.0 never change the smudge color
smudge_radius_log: This modifies the radius of the circle where color is picked up for smudging. 0.0 use the brush radius -0.7 half the brush radius (fast, but not always intuitive) +0.7 twice the brush radius +1.6 five times the brush radius (slow performance)
eraser: how much this tool behaves like an eraser 0.0 normal painting 1.0 standard eraser 0.5 pixels go towards 50% transparency
stroke_threshold: How much pressure is needed to start a stroke. This affects the stroke input only. MyPaint does not need a minimum pressure to start drawing.
stroke_duration_logarithmic: How far you have to move until the stroke input reaches 1.0. This value is logarithmic (negative values will not invert the process).
stroke_holdtime: This defines how long the stroke input stays at 1.0. After that it will reset to 0.0 and start growing again, even if the stroke is not yet finished. 2.0 means twice as long as it takes to go from 0.0 to 1.0 9.9 or higher stands for infinite
custom_input: Set the custom input to this value. If it is slowed down, move it towards this value (see below). The idea is that you make this input depend on a mixture of pressure/speed/whatever, and then make other settings depend on this 'custom input' instead of repeating this combination everywhere you need it. If you make it change 'by random' you can generate a slow (smooth) random input.
custom_input_slowness: How slow the custom input actually follows the desired value (the one above). This happens at brushdab level (ignoring how much time has passed, if brushdabs do not depend on time). 0.0 no slowdown (changes apply instantly)
elliptical_dab_ratio: Aspect ratio of the dabs; must be >= 1.0, where 1.0 means a perfectly round dab.
elliptical_dab_angle: Angle by which elliptical dabs are tilted 0.0 horizontal dabs 45.0 45 degrees, turned clockwise 180.0 horizontal again
direction_filter: A low value will make the direction input adapt more quickly, a high value will make it smoother
lock_alpha: Do not modify the alpha channel of the layer (paint only where there is paint already) 0.0 normal painting 0.5 half of the paint gets applied normally 1.0 alpha channel fully locked
colorize: Colorize the target layer, setting its hue and saturation from the active brush color while retaining its value and alpha.
snap_to_pixel: Snap brush dab's center and its radius to pixels. Set this to 1.0 for a thin pixel brush.
pressure_gain_log: This changes how hard you have to press. It multiplies tablet pressure by a constant factor.
gridmap_scale: Changes the overall scale that the GridMap brush input operates on. Logarithmic (same scale as brush radius). A scale of 0 will make the grid 256x256 pixels.
gridmap_scale_x: Changes the scale that the GridMap brush input operates on - affects X axis only. The range is 0-5x. This allows you to stretch or compress the GridMap pattern.
gridmap_scale_y: Changes the scale that the GridMap brush input operates on - affects Y axis only. The range is 0-5x. This allows you to stretch or compress the GridMap pattern.
smudge_length_log: Logarithmic multiplier for the "Smudge length" value. Useful to correct for high-definition/large brushes with lots of dabs. The longer the smudge length the more a color will spread and will also boost performance dramatically, as the canvas is sampled less often
smudge_bucket: There are 256 buckets that each can hold a color picked up from the canvas. You can control which bucket to use to improve variability and realism of the brush. Especially useful with the "Custom input" setting to correlate buckets with other settings such as offsets.
smudge_transparency: Control how much transparency is picked up and smudged, similar to lock alpha. 1.0 will not move any transparency. 0.5 will move only 50% transparency and above. 0.0 will have no effect. Negative values do the reverse
offset_y: Moves the dabs up or down based on canvas coordinates.
offset_x: Moves the dabs left or right based on canvas coordinates.
offset_angle: Follows the stroke direction to offset the dabs to one side.
offset_angle_asc: Follows the tilt direction to offset the dabs to one side. Requires Tilt.
offset_angle_view: Follows the view orientation to offset the dabs to one side.
offset_angle_2: Follows the stroke direction to offset the dabs, but to both sides of the stroke.
offset_angle_2_asc: Follows the tilt direction to offset the dabs, but to both sides of the stroke. Requires Tilt.
offset_angle_2_view: Follows the view orientation to offset the dabs, but to both sides of the stroke.
offset_angle_adj: Change the Angular Offset angle from the default, which is 90 degrees.
offset_multiplier: Logarithmic multiplier for X, Y, and Angular Offset settings.
posterize: Strength of posterization, reducing number of colors based on the "Posterization levels" setting, while retaining alpha.
posterize_num: Number of posterization levels (divided by 100). 0.05 = 5 levels, 0.2 = 20 levels, etc. Values above 0.5 may not be noticeable.
paint_mode: Subtractive spectral color mixing mode. 0.0 no spectral mixing 1.0 only spectral mixing

Value

A reusable brush specification object.

Examples

ex_file <- tempfile(fileext = ".png")
mypaint_device(ex_file)

plot.new()
plot.window(c(0, 10), c(0, 10))
rect(2, 0, 4, 10, col = "orange")
pen <- load_brush("classic/pen")
set_brush(pen)
abline(h = 9, lwd = 3)
set_brush(tweak_brush(pen, dabs_per_actual_radius = 0.5))
abline(h = 7, lwd = 3)
set_brush(tweak_brush(pen, radius_logarithmic = 1.5))
abline(h = 5, lwd = 3)
set_brush(tweak_brush(pen, opaque = 0.5))
abline(h = 3, lwd = 3)
set_brush(tweak_brush(pen, radius_by_random = 0.2))
abline(h = 1, lwd = 3)

dev.off()
#> agg_record_1d95a79c08c 
#>                      2 
img <- png::readPNG(ex_file)
grid::grid.raster(img)

Tweak a brush specification

Usage

Arguments

Value

See also

Examples