From b377bbac5983a044b80b43adcb3d871eebee4d25 Mon Sep 17 00:00:00 2001
From: plex <344565768@qq.com>
Date: Wed, 18 Jul 2018 22:43:45 +0800
Subject: [PATCH] fix: change the start angle of the regular polygon to match
 the sketch

---
 src/ol/interaction/Draw.js | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/ol/interaction/Draw.js b/src/ol/interaction/Draw.js
index 52796f5e96..81f7f1fb91 100644
--- a/src/ol/interaction/Draw.js
+++ b/src/ol/interaction/Draw.js
@@ -956,8 +956,19 @@ export function createRegularPolygon(opt_sides, opt_angle) {
       squaredCoordinateDistance(center, end));
     const geometry = opt_geometry ? /** @type {module:ol/geom/Polygon} */ (opt_geometry) :
       fromCircle(new Circle(center), opt_sides);
-    const angle = opt_angle ? opt_angle :
+    let angle = opt_angle ? opt_angle :
       Math.atan((end[1] - center[1]) / (end[0] - center[0]));
+    let _angle = 180 * angle / Math.PI;
+    if (end[0] - center[0] >= 0 && end[1] - center[1] <= 0) {
+      _angle = _angle + 360;
+    } else if (end[0] - center[0] >= 0 && end[1] - center[1] >= 0) {
+      _angle = _angle;
+    } else if (end[0] - center[0] <= 0 && end[1] - center[1] >= 0) {
+      _angle = _angle + 180;
+    } else if (end[0] - center[0] <= 0 && end[1] - center[1] <= 0) {
+      _angle = _angle + 180;
+    }
+    angle = _angle * Math.PI / 180;
     makeRegular(geometry, center, radius, angle);
     return geometry;
   };