Draw board game pieces with ggplot2

geom_piece() creates a ggplot2 geom. aes_piece() takes a data frame and generates an appropriate ggplot2::aes() mapping.

Usage

geom_piece(
  mapping = NULL,
  data = NULL,
  stat = "identity",
  position = "identity",
  ...,
  envir = getOption("piecepackr.envir", piecepackr::game_systems()),
  op_scale = getOption("piecepackr.op_scale", 0),
  op_angle = getOption("piecepackr.op_angle", 45),
  inherit.aes = TRUE
)

aes_piece(df)

Arguments

mapping

Set of aesthetic mappings created by aes(). If specified and inherit.aes = TRUE (the default), it is combined with the default mapping at the top level of the plot. You must supply mapping if there is no plot mapping.

data

The data to be displayed in this layer. There are three options:

If NULL, the default, the data is inherited from the plot data as specified in the call to ggplot().

A data.frame, or other object, will override the plot data. All objects will be fortified to produce a data frame. See fortify() for which variables will be created.

A function will be called with a single argument, the plot data. The return value must be a data.frame, and will be used as the layer data. A function can be created from a formula (e.g. ~ head(.x, 10)).

stat

The statistical transformation to use on the data for this layer. When using a geom_*() function to construct a layer, the stat argument can be used to override the default coupling between geoms and stats. The stat argument accepts the following:

• A Stat ggproto subclass, for example StatCount.

• A string naming the stat. To give the stat as a string, strip the function name of the stat_ prefix. For example, to use stat_count(), give the stat as "count".

• For more information and other ways to specify the stat, see the layer stat documentation.

position

A position adjustment to use on the data for this layer. This can be used in various ways, including to prevent overplotting and improving the display. The position argument accepts the following:

• The result of calling a position function, such as position_jitter(). This method allows for passing extra arguments to the position.

• A string naming the position adjustment. To give the position as a string, strip the function name of the position_ prefix. For example, to use position_jitter(), give the position as "jitter".

• For more information and other ways to specify the position, see the layer position documentation.

...

Aesthetics, used to set an aesthetic to a fixed value.

envir

Environment (or named list) containing configuration list(s).

op_scale

How much to scale the depth of the piece in the oblique projection (viewed from the top of the board). 0 (the default) leads to an “orthographic” projection, 0.5 is the most common scale used in the “cabinet” projection, and 1.0 is the scale used in the “cavalier” projection.

op_angle

What is the angle of the oblique projection? Has no effect if op_scale is 0.

inherit.aes

If FALSE, overrides the default aesthetics, rather than combining with them. This is most useful for helper functions that define both data and aesthetics and shouldn't inherit behaviour from the default plot specification, e.g. annotation_borders().

df

A data frame of game piece information with (at least) the named columns “piece_side”, “x”, and “y”.

Details

geom_piece() requires a fixed scale coordinate system with an aspect ratio of 1 as provided by ggplot2::coord_fixed(). geom_piece() also requires that cfg is a character vector (and not a pp_cfg() object). In particular if using op_transform() one should set its argument cfg_class = "character" if intending for use with geom_piece().

Aesthetics

geom_piece() understands the following aesthetics (required aesthetics are in bold). See pieceGrob() for more details.

• x

• y

• z

• piece_side

• rank

• suit

• cfg

• width

• height

• depth

• angle

• scale

• type

See also

geom_piece() is a wrapper around pieceGrob(). scale_x_piece() and scale_y_piece() are wrappers around ggplot2::scale_x_continuous() and ggplot2::scale_y_continuous() with better defaults for board game diagrams.

Examples

if (require("ggplot2", quietly = TRUE) && require("tibble", quietly = TRUE)) {
  envir <- game_systems("sans")
  df_board <- tibble(piece_side = "board_face", suit = 3, rank = 8,
                 x = 4.5, y = 4.5)
  df_w <- tibble(piece_side = "bit_back", suit = 6, rank = 1,
                 x = rep(1:8, 2), y = rep(1:2, each=8))
  df_b <- tibble(piece_side = "bit_back", suit = 1, rank = 1,
                 x = rep(1:8, 2), y = rep(7:8, each=8))
  df <- rbind(df_board, df_w, df_b)
  # 2D example
  # `cfg` must be a character vector for `geom_piece()`
  ggplot(df, aes_piece(df)) +
      geom_piece(cfg = "checkers1", envir = envir) +
      coord_fixed() +
      scale_x_piece() +
      scale_y_piece() +
      theme_minimal(28) +
      theme(panel.grid = element_blank())
}

if (require("ggplot2", quietly = TRUE) && require("tibble", quietly = TRUE)) {
  # 3D "oblique" projection example
  # `cfg_class` must be "character" when using with `geom_piece()`
  df3d <- op_transform(df, cfg = "checkers1", envir = envir,
                       op_angle = 45, cfg_class = "character")
  ggplot(df3d, aes_piece(df3d)) +
      geom_piece(cfg = "checkers1", envir = envir,
                 op_angle = 45, op_scale = 0.5) +
      coord_fixed() +
      theme_void()
}