Swarm Art in the Browser

This article documents an optional downstream bridge from boids4R into ggWebGL. The creative use case is generative browser art: compact schools, predator avoidance, obstacle corridors, murmurations, and mixed-species swarms become animated point/vector timelines that can be panned, zoomed, scrubbed, and inspected in WebGL.

The CRAN-built vignette is documentation-only. It does not load boids4R, does not execute GitHub-only package code, and does not require optional ecosystem packages to be installed. The runnable bridge remains in the package example script named below.

Boundary

The ownership split is deliberately narrow:

• boids4R owns simulation semantics: flocking state, rules, scenarios, and frame export.
• The optional downstream bridge translates simulation frames into renderer primitives when boids4R is installed separately.
• ggWebGL owns WebGL rendering: the htmlwidget, point and vector primitives, shader choice, timeline controls, hover, pan, zoom, and 3D orbit interaction.

This keeps the core ggWebGL package self-contained for CRAN while preserving a clear optional integration path for development installations.

Runnable Optional Demo

The optional example script is:

inst/examples/htmlwidget/downstream-boids4r-animation.R

When boids4R is installed separately, the script builds two widgets:

• a 2D schooling scene rendered as exact-frame animated points and vectors
• a 3D murmuration scene rendered with the structured 3D view path

To run it in a development checkout or installed package, use:

source(system.file("examples", "htmlwidget", "downstream-boids4r-animation.R", package = "ggWebGL"))
widgets <- downstream_boids4r_widgets()
widgets$schooling_2d
widgets$murmuration_3d

The script is guarded: if boids4R is absent, it reports that the optional demo was skipped instead of failing package checks.

What To Inspect

The optional widgets are intended to demonstrate renderer capabilities rather than package-specific simulation interpretation:

• point primitives carry boid positions for each frame
• vector primitives show local velocity direction
• exact timeline filtering makes each scrubbed frame visually distinct
• 3D view metadata enables the murmuration scene to use browser camera controls
• shader settings remain owned by ggWebGL, not by the simulation package

CRAN Position

boids4R is an optional development ecosystem package. It is not listed in ggWebGL dependencies and is not required for installation, examples, tests, or vignettes. This article is retained as a documentation entry so downstream packages can see the intended adapter boundary without making CRAN checks depend on GitHub-only packages.