Introducing two new attributes to enable property functions for line-width (#9250) pushed the attribute count over GL_MAX_VERTEX_ATTRIBS on some devices. Now we selectively bind only attributes that are used, making it unlikely to surpass GL_MAX_VERTEX_ATTRIBS.
* Update gl-js and generate style code
* Factor out packUint8Pair() helper function
* Draft implementation of DDS for {text,icon}-size
Ports https://github.com/mapbox/mapbox-gl-js/pull/4455
* Fix text-size/composite-function-line-placement test
* Refactor to PaintPropertyBinders-like strategy
* Dedupe gl::Program construction
* Use exponential function base for interpolation
* Dedupe coveringZoomStops method
* Fixup tests
* Fix CI errors (hidden within #if block)
Two reasons to prefer explicit sequential location assignment, rather than relying on the GLSL linker to assign locations:
* For data-driven properties, we want to have the option to use glDisableVertexAttribArray plus glVertexAttrib*. In order to use glDisableVertexAttribArray, we must avoid using attribute location 0, which cannot be disabled.
* We want to use the same VAO in cases where, say, a fill layer might be rendered with FillProgram at first, and then FillPatternProgram later. VAOs do not store the program binding, only the attribute bindings, so as long as the two programs have the same attributes and attribute locations, only a single VAO (per segment) is needed.
* Extract `ignore` util to separate header.
* `Segment` now tracks offset and length of indices, rather than primitives. This is more natural.
* Introduce `VertexVector` and `IndexVector` types. These types carry information about the intended draw mode (`Triangles`, `LineStrip`, etc.), and ensure that elements are always appended in a group size appropriate for that draw mode, for both indexed and unindexed rendering.
* `Program`, rather than `Drawable`, is now the unifying object for draw calls. `Program` is the best place to type check the draw call, because it is typed to carry information about the intended primitive, vertex type, attributes, and uniforms.
* Use the debug shaders for debug tile rendering, like gl-js.
* Fix the draw mode for background. It was drawing triangle strips with a triangles array. Surprised this didn’t cause issues. Now it’s type checked.
