Enable property functions for text-halo-color

js/data/bucket/symbol_bucket.js

@@ -43,7 +43,8 @@ const symbolInterfaces = {
         layoutVertexArrayType: layoutVertexArrayType,
         elementArrayType: elementArrayType,
         paintAttributes: [
-            {property: 'text-color', type: 'Uint8'}
+            {property: 'text-color', type: 'Uint8'},
+            {property: 'text-halo-color', type: 'Uint8'}
         ]
     },
     icon: {

js/render/draw_symbol.js

@@ -186,10 +186,12 @@ function drawTileSymbols(program, painter, layer, tile, buffers, isText, isSDF,
         if (haloWidth) { // Draw halo underneath the text.
             gl.uniform1f(program.u_gamma, (haloBlur * blurOffset / sdfPx + gamma) / gammaScale);
             gl.uniform1f(program.u_buffer, (haloOffset - haloWidth / fontScale) / sdfPx);
+            gl.uniform1f(program.u_is_halo, 1);
 
             drawSymbolElements(buffers, layer, gl, program);
         }
 
+        gl.uniform1f(program.u_is_halo, 0);
         gl.uniform1f(program.u_gamma, gamma / gammaScale);
         gl.uniform1f(program.u_buffer, (256 - 64) / 256);
     }

js/style-spec/reference/v8.json

@@ -2675,6 +2675,7 @@
       "default": "rgba(0, 0, 0, 0)",
       "function": "interpolated",
       "zoom-function": true,
+      "property-function": true,
       "transition": true,
       "doc": "The color of the text's halo, which helps it stand out from backgrounds.",
       "requires": [

shaders/symbol_sdf.fragment.glsl

@@ -1,24 +1,32 @@
 #pragma mapbox: define lowp vec4 color
+#pragma mapbox: define lowp vec4 halo_color
 
 uniform sampler2D u_texture;
 uniform sampler2D u_fadetexture;
 uniform lowp float u_opacity;
 uniform lowp float u_buffer;
 uniform lowp float u_gamma;
+uniform bool u_is_halo;
 
 varying vec2 v_tex;
 varying vec2 v_fade_tex;
 varying float v_gamma_scale;
 
 void main() {
     #pragma mapbox: initialize lowp vec4 color
+    #pragma mapbox: initialize lowp vec4 halo_color
+
+    lowp vec4 color_to_use = color;
+    if (u_is_halo) {
+        color_to_use = halo_color;
+    }
 
     lowp float dist = texture2D(u_texture, v_tex).a;
     lowp float fade_alpha = texture2D(u_fadetexture, v_fade_tex).a;
     lowp float gamma = u_gamma * v_gamma_scale;
     lowp float alpha = smoothstep(u_buffer - gamma, u_buffer + gamma, dist) * fade_alpha;
 
-    gl_FragColor = color * (alpha * u_opacity);
+    gl_FragColor = color_to_use * (alpha * u_opacity);
 
 #ifdef OVERDRAW_INSPECTOR
     gl_FragColor = vec4(1.0);

shaders/symbol_sdf.vertex.glsl

@@ -6,6 +6,7 @@ attribute vec2 a_texture_pos;
 attribute vec4 a_data;
 
 #pragma mapbox: define lowp vec4 color
+#pragma mapbox: define lowp vec4 halo_color
 
 // matrix is for the vertex position.
 uniform mat4 u_matrix;
@@ -26,6 +27,7 @@ varying float v_gamma_scale;
 
 void main() {
     #pragma mapbox: initialize lowp vec4 color
+    #pragma mapbox: initialize lowp vec4 halo_color
 
     vec2 a_tex = a_texture_pos.xy;
     mediump float a_labelminzoom = a_data[0];