[core] improve text-max-angle check

Instead of using the absolute value of the sum of angles, use the sum of
the absolute values of angles.

This helps avoid labels on lines with sharp zig zags.

for example, the "Central Campus Mall" label in issue #2998

1 files changed, 2 insertions, 2 deletions

diff --git a/src/mbgl/text/check_max_angle.cpp b/src/mbgl/text/check_max_angle.cpp
index 6e94c2ec17..bb32e4235e 100644
--- a/src/mbgl/text/check_max_angle.cpp
+++ b/src/mbgl/text/check_max_angle.cpp
@@ -51,7 +51,7 @@ bool checkMaxAngle(const std::vector<Coordinate> &line, Anchor &anchor, const fl
 
         float angleDelta = util::angle_to(prev, current) - util::angle_to(current, next);
         // restrict angle to -pi..pi range
-        angleDelta = std::fmod(angleDelta + 3 * M_PI, M_PI * 2) - M_PI;
+        angleDelta = std::fabs(std::fmod(angleDelta + 3 * M_PI, M_PI * 2) - M_PI);
 
         recentCorners.emplace(anchorDistance, angleDelta);
         recentAngleDelta += angleDelta;
@@ -63,7 +63,7 @@ bool checkMaxAngle(const std::vector<Coordinate> &line, Anchor &anchor, const fl
         }
 
         // the sum of angles within the window area exceeds the maximum allowed value. check fails.
-        if (std::fabs(recentAngleDelta) > maxAngle) return false;
+        if (recentAngleDelta > maxAngle) return false;
 
         index++;
         anchorDistance += util::dist<float>(current, next);