1 files changed, 25 insertions, 0 deletions
diff --git a/src/mbgl/shader/line.fragment.glsl b/src/mbgl/shader/line.fragment.glsl
new file mode 100644
index 0000000000..f4ac1458b3
--- /dev/null
+++ b/src/mbgl/shader/line.fragment.glsl
@@ -0,0 +1,25 @@
+uniform vec2 u_linewidth;
+uniform vec4 u_color;
+uniform float u_blur;
+
+uniform vec2 u_dasharray;
+
+varying vec2 v_normal;
+varying float v_linesofar;
+
+void main() {
+    // Calculate the distance of the pixel from the line in pixels.
+    float dist = length(v_normal) * u_linewidth.s;
+
+    // Calculate the antialiasing fade factor. This is either when fading in
+    // the line in case of an offset line (v_linewidth.t) or when fading out
+    // (v_linewidth.s)
+    float alpha = clamp(min(dist - (u_linewidth.t - u_blur), u_linewidth.s - dist) / u_blur, 0.0, 1.0);
+
+    // Calculate the antialiasing fade factor based on distance to the dash.
+    // Only affects alpha when line is dashed
+    float pos = mod(v_linesofar, u_dasharray.x + u_dasharray.y);
+    alpha *= max(step(0.0, -u_dasharray.y), clamp(min(pos, u_dasharray.x - pos), 0.0, 1.0));
+
+    gl_FragColor = u_color * alpha;
+}