Rewrite ProgramConfiguration

[jfirebaugh]

• Expand #pragmas to #ifndefs early on. This is written in such a way that it can be reused by gl-native's generate-shaders.js. It also avoids generating unnecessary varyings (Reduce number of varyings for line_sdf shader #4542).
• Binder interface for paint properties, with a concrete implementation for each binding strategy.
• Always use floats for paint property attributes, without a multiplication factor. (Fixes DDS extrusion-heights get Math.floor'ed #4438. Fixes Support extrusion heights over 65km #3954.)
• When binding composite functions, interpolate between two stop values only: zoom and zoom + 1.

benchmark	master 83fb52d	rewrite-program-configuration 96e5fb8
map-load	99 ms	83 ms
style-load	67 ms	60 ms
buffer	1,002 ms	945 ms
fps	60 fps	60 fps
frame-duration	5.1 ms, 0% > 16ms	5.4 ms, 0% > 16ms
query-point	0.78 ms	0.87 ms
query-box	50.73 ms	50.52 ms
geojson-setdata-small	4 ms	4 ms
geojson-setdata-large	129 ms	130 ms

Launch Checklist

• briefly describe the changes in this PR
• post benchmark scores
• manually test the debug page

[mourner]

Awesome! Do you know if there's a performance impact from the float type change? Would it cause more data to be uploaded?

[anandthakker]

🍏 (notwithstanding two minor suggestions)

[anandthakker]

I think the return type here should be [number, number].

[anandthakker]

I'd favor the more explicit if (operation === 'define') ... else if (operation === 'initialize') (or the equivalent switch) here and below, so as to (re-)articulate how our custom #pragma syntax works.

[jfirebaugh]

Do you know if there's a performance impact from the float type change? Would it cause more data to be uploaded?

Yes, in some cases -- I believe the majority -- the buffers for data-driven properties will be larger. For source functions, non-color data-driven properties that were previously typed as Uint8 will use 4x space; Uint16 and color properties, 2x. For composite functions, it depends on how many stops the function uses and the type of the property. Color properties will generally use less space. Functions with four or more stops will generally use less space. Other composite functions will generally use the same amount of space or more space. The space for non-data-driven property values is unchanged.

Overall, I expect the space increase to have a minor impact, and I think it's worth it to simplify the implementation, make gl-js consistent with gl-native, and eliminate bugs like #3954 and #4438 where using a 16-bit integer results in truncation and limited range.