The WebGLPointsLayer class has been around for a while and seems to be used quite a bit. We have been working on the more generic vector layer renderer for a while, but there hasn't been any proper easy-to-use class yet for that renderer.

Now that the generic vector renderer is working well, we propose to:

• Deprecate the WebGLPointsLayer class: it won't be maintained and will be removed in the n+1 major version; it should work moslty the same until then
• Introduce the WebGLVectorLayer class
• Introduce a way to specify style variables through this class API

The usage of the WebGLVectorLayer class would look like this:

const layer = new WebGLVectorLayer({
	source: …,
	style: [{
		'stroke-color': ['var', 'lineColor']
	}],
	styleVariables: {
		lineColor: 'yellow'
	}
})

The ['var'] operator will still be supported but target the styleVariables property instad of the variables property in the style object. The layer API will also offer an updateStyleVariables function, similarly to the WebGLPointsLayer class.

This addresses at least partly #15146.

This proposal should result in a more easy-to-use and optimized WebGL-based layer. The generic vector layer is also better optimized and should offer better performance.

This proposal will also pave the way for the following improvements:

• implement style variables and ['var'] in a similar way for canvas-based layers
• get rid of the webgl-specific style format and use the flat style format everywhere
• implement cascading style variables on the Map and LayerGroup objects (to be discussed further)

Please share any opinion/questions!

Done in cooperation with @romprokop