fix rotation range check in text shader

fixes #215

src/map/tile_parser.cpp

@@ -142,7 +142,6 @@ std::unique_ptr<Bucket> TileParser::createIconBucket(const VectorTileLayer& laye
 }
 
 std::unique_ptr<Bucket> TileParser::createTextBucket(const VectorTileLayer& layer, const BucketDescription& bucket_desc) {
-    return nullptr;
 
     // Determine the correct text stack.
     if (!layer.shaping.size()) {

src/shader/text.vertex.glsl

@@ -62,7 +62,7 @@ void main() {
 
     // all the angles are 0..256 representing 0..2PI
     // hide if (angle >= a_rangeend && angle < rangestart)
-    z += (1.0 - step(a_range[0], u_angle)) * step(a_range[1], u_angle);
+    z += step(a_range[0], u_angle) * (1.0 - step(a_range[1], u_angle));
 
     gl_Position = u_matrix * vec4(a_pos, 0, 1) + u_exmatrix * vec4(a_offset / 64.0, z, 0);
     v_tex = a_tex * 4.0 / u_texsize;