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3D line segments

Source: R/geom-segment-3d.R
geom_segment_3d.Rd

geom_segment_3d() and stat_segment_3d() draw line segments in 3D space with automatic depth-based linewidth scaling and proper depth sorting. Each segment is defined by start coordinates (x, y, z) and end coordinates (xend, yend, zend).

Usage

geom_segment_3d(
  mapping = NULL,
  data = NULL,
  stat = StatSegment3D,
  position = "identity",
  ...,
  sort_method = "painter",
  scale_depth = TRUE,
  arrow = NULL,
  lineend = "butt",
  na.rm = FALSE,
  show.legend = NA,
  inherit.aes = TRUE
)

stat_segment_3d(
  mapping = NULL,
  data = NULL,
  geom = GeomSegment3D,
  position = "identity",
  ...,
  sort_method = "painter",
  scale_depth = TRUE,
  arrow = NULL,
  lineend = "butt",
  na.rm = FALSE,
  show.legend = NA,
  inherit.aes = TRUE
)

Arguments

mapping

Set of aesthetic mappings created by aes(). Requires x, y, z for start coordinates and xend, yend, zend for end coordinates.

data

The data to be displayed in this layer.

stat

The statistical transformation to use on the data. Defaults to "segment_3d".

position

Position adjustment, defaults to "identity".

...

Other arguments passed on to ggplot2::layer().

sort_method

Character indicating algorithm used to determine the order in which elements are rendered. This controls depth sorting for all geometry types within a layer, including polygons, points, segments, and text. Default varies by geometry type.

  • "painter": Elements are sorted by the mean depth (distance from viewer after rotation) of their vertices. This is fast, but can give incorrect results when primitives overlap in screen space at different depths.

  • "pairwise": A more intensive sorting algorithm that compares every pair of elements to determine occlusion order. Uses type-specific geometric tests: polygon overlap detection for polygon-polygon pairs, point-in-polygon tests for polygon-point pairs, line clipping for polygon-segment pairs, and line intersection for segment-segment pairs. When elements are coplanar, smaller primitives (points, segments) render on top of larger ones (polygons). Slower but more accurate.

  • "auto": Uses pairwise if the data has fewer than 500 rows, and painter otherwise.

scale_depth

Logical indicating whether to apply depth-based scaling to linewidth. When TRUE (default), segments closer to the viewer appear thicker, and segments farther away appear thinner.

arrow

Specification for arrow heads, created by arrow().

lineend

Line end style, one of "round", "butt", "square".

na.rm

If FALSE, missing values are removed with a warning.

show.legend

Logical indicating whether this layer should be included in legends.

inherit.aes

If FALSE, overrides the default aesthetics.

geom

The geometric object used to display the data. Defaults to "segment_3d".

Value

A Layer object that can be added to a ggplot.

Aesthetics

geom_segment_3d() understands the following aesthetics:

  • x, y, z: Start coordinates (required)

  • xend, yend, zend: End coordinates (required)

  • colour: Line color

  • linewidth: Line width (gets depth-scaled when scale_depth = TRUE)

  • linetype: Line type

  • alpha: Transparency

See also

geom_path_3d() for connected paths.

Examples

# Basic 3D segments
ggplot(sphere_points,
      aes(x, y, z, xend = 0, yend = 0, zend = 0)) +
  geom_segment_3d() +
  coord_3d()


# 3D vector field
data <- expand.grid(x = -1:2, y = -1:2, z = -1:2)
data2 <- data + seq(-.5, .5, length.out = length(as.matrix(data)))
data <- cbind(data, setNames(data2, c("x2", "y2", "z2")))
ggplot(data, aes(x, y, z,
      xend = x2, yend = y2, zend = z2, color = x)) +
  geom_segment_3d(arrow = arrow(length = unit(0.1, "inches"),
                  type = "closed", angle = 15),
                  linewidth = .5) +
  coord_3d()