If you want to do SVGs, snap.js is a modern SVG library by the author of raphaël.js.
See plotting on the web.
3D seem the browser is convenient and somewhat performant. More convenient, than Processing. And you can do 3d dance parties in the browser, which is a pretty thorough test.
Two common options use OpenGL ES, the mobile- and browser- friendly option.
- Scenejs seems to specialise in loading up geometries and shapes and physics for realistic scene modelling
- three.js does the same things, but does more abstract stuff with them
- shadertoy support writing raw GSL shaders in the browser.
Everything supports lense flare, which is the main thing.
For desktop apps and a larger OpenGL subset there is a desktop option, Plask which seems to be some kind of particle-system-friendly, macOS app, with spurty development but nifty potential.
- Threefab designs THREE.js scenes.
- Nunustudio does too (source code )
- Livecodelab (source)