Core ggplot-like WebGL layers

This vignette covers the core two-dimensional ggplot2-style layers and the renderer-ready specification workflow. The code examples construct ggplot2-style WebGL layers and, when evaluated, convert them into browser-side WebGL htmlwidgets with ggplot_webgl() or ggWebGL().

Code evaluation is disabled during CRAN, package checks, and CI unless explicitly enabled with GGWEBGL_EVAL_COVERAGE_VIGNETTE=true or NOT_CRAN=true. Live WebGL widget rendering is additionally disabled unless GGWEBGL_EVAL_LIVE_WIDGETS=true is set. Rich local or pkgdown builds should set both GGWEBGL_EVAL_COVERAGE_VIGNETTE=true and GGWEBGL_EVAL_LIVE_WIDGETS=true.

Two Workflows

Applet: Grammar-style points and lines

p <- ggplot(mtcars, aes(wt, mpg, colour = factor(cyl))) +
  geom_point_webgl() +
  geom_line_webgl(aes(group = cyl), alpha = 0.35) +
  labs(title = "Grammar-style points and lines") +
  theme_webgl(shader = "density_splat")

ggplot_webgl(p, height = 420)

Applet: Renderer-ready point specification

Renderer-ready specifications are useful when data have already been transformed into primitive payloads.

spec <- ggwebgl_spec(
  layers = list(
    ggwebgl_layer_points(mtcars, x = "wt", y = "mpg", colour = "#2563eb")
  ),
  labels = list(title = "Renderer-ready point specification"),
  webgl = webgl_spec(shader = "density_splat")
)

ggWebGL(spec)

Coverage Summary

Family	Public APIs	Status	Notes
Points	geom_point_webgl()	Stable	Core scatter and dense point rendering.
Lines and paths	geom_line_webgl(), geom_path_webgl(), geom_path3d_webgl()	Stable / Experimental	Two-dimensional line/path rendering is core; 3D paths are experimental.
Segments and vectors	geom_segment_webgl(), geom_vector_webgl()	Stable / Experimental	Segments are plain line segments; vectors add arrow-oriented metadata.
Rectangles and tiles	geom_rect_webgl(), geom_tile_webgl()	Stable	Uses ggplot2-built rectangle bounds.
Count and bin geoms	geom_bar_webgl(), geom_histogram_webgl(), geom_bin2d_webgl()	Experimental	Counts and bins are computed by ggplot2; WebGL serialization is newer than core point/line/raster paths.
Curves and contours	geom_freqpoly_webgl(), geom_density_webgl(), geom_density2d_webgl(), geom_contour_webgl()	Experimental	Rendered as line/path primitives; see the statistical coverage vignette.

Status labels reflect API maturity, test coverage, and rendering-contract stability; they are not simply an export list.

Core 2D Layers

Applet: Ordered 2D path with segments

trajectory <- data.frame(
  x = cos(seq(0, 2 * pi, length.out = 48)) * seq(0.2, 1, length.out = 48),
  y = sin(seq(0, 2 * pi, length.out = 48)) * seq(0.2, 1, length.out = 48),
  frame = seq_len(48),
  group = "spiral"
)

arrows <- data.frame(
  x = c(-0.8, -0.2, 0.4),
  y = c(-0.6, 0.1, 0.5),
  xend = c(-0.45, 0.15, 0.75),
  yend = c(-0.25, 0.35, 0.2)
)

p <- ggplot(trajectory, aes(x, y, group = group)) +
  geom_path_webgl(aes(frame = frame), colour = "#2563eb", linewidth = 1.2) +
  geom_point_webgl(aes(frame = frame), colour = "#0f766e", size = 1.8) +
  geom_segment_webgl(
    data = arrows,
    aes(x = x, y = y, xend = xend, yend = yend),
    inherit.aes = FALSE,
    colour = "#334155"
  ) +
  labs(title = "Ordered 2D path with segments")

ggplot_webgl(p, height = 420)

Applet: Line sorting versus path order

geom_line_webgl() keeps the usual line semantics, while geom_path_webgl() preserves row order within groups.

ordered <- data.frame(
  x = c(3, 1, 2, 4),
  y = c(1, 3, 2, 4),
  group = "ordered"
)

p <- ggplot(ordered, aes(x, y, group = group)) +
  geom_line_webgl(colour = "#64748b") +
  geom_path_webgl(colour = "#dc2626", linewidth = 1.2) +
  labs(title = "Line sorting versus path order")

ggplot_webgl(p, height = 420)

Rectangles, Tiles, and Bins

Rectangle-style geoms use boundaries computed by ggplot2::ggplot_build(). This keeps position adjustments and statistical transformations owned by ggplot2.

Applet: Tile grid

tile_grid <- expand.grid(
  x = seq_len(5),
  y = seq_len(4),
  KEEP.OUT.ATTRS = FALSE
)
tile_grid$value <- with(tile_grid, sin(x / 2) + cos(y / 2))

p <- ggplot(tile_grid, aes(x, y, fill = value)) +
  geom_tile_webgl(alpha = 0.85) +
  labs(title = "Tile grid")
ggplot_webgl(p, height = 420)

Applet: Stacked bar counts

p <- ggplot(mtcars, aes(factor(cyl), fill = factor(am))) +
  geom_bar_webgl(position = "stack") +
  labs(title = "Stacked bar counts")
ggplot_webgl(p, height = 420)

Applet: Histogram bins

p <- ggplot(mtcars, aes(mpg)) +
  geom_histogram_webgl(binwidth = 4) +
  labs(title = "Histogram bins")
ggplot_webgl(p, height = 420)

Applet: Two-dimensional bins

p <- ggplot(mtcars, aes(wt, mpg)) +
  geom_bin2d_webgl(bins = 8) +
  labs(title = "Two-dimensional bins")
ggplot_webgl(p, height = 420)

Applet: Explicit rectangles

rectangles <- data.frame(
  xmin = c(0.0, 1.2),
  xmax = c(1.0, 2.0),
  ymin = c(0.0, 0.4),
  ymax = c(0.8, 1.4),
  label = c("a", "b")
)

p <- ggplot(rectangles) +
  geom_rect_webgl(
    aes(xmin = xmin, xmax = xmax, ymin = ymin, ymax = ymax, fill = label),
    alpha = 0.75
  ) +
  labs(title = "Explicit rectangles")

ggplot_webgl(p, height = 420)

Curves and Contours

Curve and contour applets are in vignette("ggplot-coverage-summaries", package = "ggWebGL") so this page keeps its live widget count moderate.