[core] Implement data-driven styling for {text,icon}-{color,opacity,halo-color,halo-blur,halo-width} (#7939)

* Add symbol dds attributes and adapt style code generation

* Update to mapbox-gl-js/master

* Refactor SymbolFeature as a subclass of GeometryTileFeature

Prepares for enabling DDS on symbol paint properties by allowing the
SymbolFeatures, which we keep around after constructing SymbolLayout,
to be used in evaluating data-driven paint properties later in the
layout process.

* Draft approach for splitting icon/text paint properties

The `Program` types are set up to bind GL attributes to each of the
data-driven paint properties specified in the `PaintProperties` type
provided.  Since `SymbolPaintProperties` specifies both `Text*` and
`Icon*` properties, the symbolIcon, symbolIconSDF, and symbolGlyph
programs each attempt to bind roughly double the number of attributes
that they actually need.

This change addresses this by:
- Adding the more specific `IconPaintProperties` and `TextPaintProperties` types, which are subsets of the full `SymbolPaintProperties`.
- The symbol layer continues to use its `SymbolPaintProperties paint` member to track layer property state, but it provides helpers that construct objects of each the specific `{Icon,Text}PaintProperties::Evaluated` type, for use by the painter.
- The three symbol programs instantiate `Program<>` using the appropriate `{Icon,Text}PaintProperties` type.

* check in generated style code

* Populate paint buffers for symbol DDS properties

* Address first round of review comments

* Refactor VectorTile{Layer,Feature} to explicitly share data

* Update submodule

1 files changed, 52 insertions, 25 deletions

diff --git a/src/mbgl/programs/symbol_program.hpp b/src/mbgl/programs/symbol_program.hpp
index e0e90f0fa4..0537c25a2c 100644
--- a/src/mbgl/programs/symbol_program.hpp
+++ b/src/mbgl/programs/symbol_program.hpp
@@ -8,6 +8,7 @@
 #include <mbgl/util/geometry.hpp>
 #include <mbgl/util/size.hpp>
 #include <mbgl/style/layers/symbol_layer_properties.hpp>
+#include <mbgl/style/layers/symbol_layer_impl.hpp>
 
 #include <cmath>
 #include <array>
@@ -27,9 +28,10 @@ MBGL_DEFINE_UNIFORM_SCALAR(bool, u_rotate_with_map);
 MBGL_DEFINE_UNIFORM_SCALAR(bool, u_pitch_with_map);
 MBGL_DEFINE_UNIFORM_SCALAR(gl::TextureUnit, u_texture);
 MBGL_DEFINE_UNIFORM_SCALAR(gl::TextureUnit, u_fadetexture);
-MBGL_DEFINE_UNIFORM_SCALAR(float, u_buffer);
-MBGL_DEFINE_UNIFORM_SCALAR(float, u_gamma);
 MBGL_DEFINE_UNIFORM_SCALAR(float, u_aspect_ratio);
+MBGL_DEFINE_UNIFORM_SCALAR(bool, u_is_halo);
+MBGL_DEFINE_UNIFORM_SCALAR(float, u_font_scale);
+MBGL_DEFINE_UNIFORM_SCALAR(float, u_gamma_scale);
 } // namespace uniforms
 
 struct SymbolLayoutAttributes : gl::Attributes<
@@ -75,14 +77,13 @@ class SymbolIconProgram : public Program<
     SymbolLayoutAttributes,
     gl::Uniforms<
         uniforms::u_matrix,
-        uniforms::u_opacity,
         uniforms::u_extrude_scale,
         uniforms::u_texsize,
         uniforms::u_zoom,
         uniforms::u_rotate_with_map,
         uniforms::u_texture,
         uniforms::u_fadetexture>,
-    style::SymbolPaintProperties>
+    style::IconPaintProperties>
 {
 public:
     using Program::Program;
@@ -94,47 +95,73 @@ public:
                                        const TransformState&);
 };
 
+enum class SymbolSDFPart {
+    Fill = 1,
+    Halo = 0
+};
+
+template <class PaintProperties>
 class SymbolSDFProgram : public Program<
     shaders::symbol_sdf,
     gl::Triangle,
     SymbolLayoutAttributes,
     gl::Uniforms<
         uniforms::u_matrix,
-        uniforms::u_opacity,
         uniforms::u_extrude_scale,
         uniforms::u_texsize,
         uniforms::u_zoom,
         uniforms::u_rotate_with_map,
         uniforms::u_texture,
         uniforms::u_fadetexture,
-        uniforms::u_color,
-        uniforms::u_buffer,
-        uniforms::u_gamma,
+        uniforms::u_font_scale,
+        uniforms::u_gamma_scale,
         uniforms::u_pitch,
         uniforms::u_bearing,
         uniforms::u_aspect_ratio,
-        uniforms::u_pitch_with_map>,
-    style::SymbolPaintProperties>
+        uniforms::u_pitch_with_map,
+        uniforms::u_is_halo>,
+    PaintProperties>
 {
 public:
-    using Program::Program;
+    using BaseProgram = Program<shaders::symbol_sdf,
+        gl::Triangle,
+        SymbolLayoutAttributes,
+        gl::Uniforms<
+            uniforms::u_matrix,
+            uniforms::u_extrude_scale,
+            uniforms::u_texsize,
+            uniforms::u_zoom,
+            uniforms::u_rotate_with_map,
+            uniforms::u_texture,
+            uniforms::u_fadetexture,
+            uniforms::u_font_scale,
+            uniforms::u_gamma_scale,
+            uniforms::u_pitch,
+            uniforms::u_bearing,
+            uniforms::u_aspect_ratio,
+            uniforms::u_pitch_with_map,
+            uniforms::u_is_halo>,
+        PaintProperties>;
+    
+    using UniformValues = typename BaseProgram::UniformValues;
+    
 
-    static UniformValues haloUniformValues(const style::SymbolPropertyValues&,
-                                           const Size& texsize,
-                                           const std::array<float, 2>& pixelsToGLUnits,
-                                           const RenderTile&,
-                                           const TransformState&,
-                                           float pixelRatio);
-
-    static UniformValues foregroundUniformValues(const style::SymbolPropertyValues&,
-                                                 const Size& texsize,
-                                                 const std::array<float, 2>& pixelsToGLUnits,
-                                                 const RenderTile&,
-                                                 const TransformState&,
-                                                 float pixelRatio);
+    
+    using BaseProgram::BaseProgram;
+
+    static UniformValues uniformValues(const style::SymbolPropertyValues&,
+                                       const Size& texsize,
+                                       const std::array<float, 2>& pixelsToGLUnits,
+                                       const RenderTile&,
+                                       const TransformState&,
+                                       const SymbolSDFPart);
 };
 
+using SymbolSDFIconProgram = SymbolSDFProgram<style::IconPaintProperties>;
+using SymbolSDFTextProgram = SymbolSDFProgram<style::TextPaintProperties>;
+
 using SymbolLayoutVertex = SymbolLayoutAttributes::Vertex;
-using SymbolAttributes = SymbolIconProgram::Attributes;
+using SymbolIconAttributes = SymbolIconProgram::Attributes;
+using SymbolTextAttributes = SymbolSDFTextProgram::Attributes;
 
 } // namespace mbgl