From badca0446d79701fc5545fe84261456f76f85ca8 Mon Sep 17 00:00:00 2001
From: "yuqi.pyq" <yuqi.pyq@antfin.com>
Date: Mon, 17 Jun 2019 16:55:18 +0800
Subject: [PATCH] =?UTF-8?q?fix(line-layer):=20=E4=BF=AE=E5=A4=8D=E7=9B=B8?=
 =?UTF-8?q?=E9=82=BB=E7=BA=BF=E6=AE=B5=E9=87=8D=E5=8F=A0=E6=83=85=E5=86=B5?=
 =?UTF-8?q?=E4=B8=8B=E7=9A=84=E6=8E=A5=E5=A4=B4=E5=A4=84=E7=90=86?=
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---
 src/util/polyline-normals.js | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/src/util/polyline-normals.js b/src/util/polyline-normals.js
index 4a104dcb06..dc6f2452ba 100644
--- a/src/util/polyline-normals.js
+++ b/src/util/polyline-normals.js
@@ -88,7 +88,28 @@ export default function(points, closed, indexOffset) {
 
       // get orientation
       let flip = (dot(tangent, _normal) < 0) ? -1 : 1;
-      const bevel = miterLen > miterLimit;
+      const bevel = Math.abs(miterLen) > miterLimit;
+
+      // 处理前后两条线段重合的情况，这种情况不需要使用任何接头（miter/bevel）。
+      // 理论上这种情况下 miterLen = Infinity，本应通过 isFinite(miterLen) 判断，
+      // 但是 AMap 投影变换后丢失精度，只能通过一个阈值（1000）判断。
+      if (Math.abs(miterLen) > 1000) {
+        normal(_normal, lineA);
+        extrusions(attrPos, out, cur, _normal, 1);
+        attrDistance.push(d, d);
+        attrIndex.push(
+          _lastFlip === 1 ? [ index + 1, index + 3, index + 2 ]
+          : [ index, index + 2, index + 3 ]
+        );
+
+        // 避免在 Material 中使用 THREE.DoubleSide
+        attrIndex.push([ index + 2, index + 3, index + 4 ]);
+
+        count += 2;
+        _lastFlip = -1;
+        continue;
+      }
+
       if (bevel) {
         miterLen = miterLimit;