[icon-layer] use sin to get 180-360 degree ranges (visgl#780)

kujon · Jul 12, 2017 · 1b83d02 · 1b83d02
1 parent a137a0e
commit 1b83d02
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/src/layers/core/icon-layer/icon-layer-vertex.glsl.js b/src/layers/core/icon-layer/icon-layer-vertex.glsl.js
@@ -44,7 +44,7 @@ varying vec2 vTextureCoords;
 vec2 rotate_by_angle(vec2 vertex, float angle) {
   float angle_radian = angle * PI / 180.0;
   float cos_angle = cos(angle_radian);
-  float sin_angle = sqrt(1.0 - cos_angle * cos_angle);
+  float sin_angle = sin(angle_radian);
   mat2 rotationMatrix = mat2(cos_angle, -sin_angle, sin_angle, cos_angle);
   return rotationMatrix * vertex;
 }