Work on closed sliced surfaces

package-lock.json

@@ -8,6 +8,7 @@
       "name": "3d-viewer",
       "version": "0.1.0",
       "dependencies": {
+        "earcut": "^3.0.1",
         "next": "15.1.7",
         "proj4": "^2.15.0",
         "react": "^19.0.0",
@@ -16,6 +17,7 @@
       },
       "devDependencies": {
         "@eslint/eslintrc": "^3",
+        "@types/earcut": "^3.0.0",
         "@types/node": "^20",
         "@types/react": "^19",
         "@types/react-dom": "^19",
@@ -854,6 +856,12 @@
       "integrity": "sha512-vJmvvwFxYuGnF2axRtPYocag6Clbb5YS7kLL+SO/TeVFzHqDIWrNKYtcsPMibjDx9O+bu+psAy9NKfWklassUA==",
       "dev": true
     },
+    "node_modules/@types/earcut": {
+      "version": "3.0.0",
+      "resolved": "https://registry.npmjs.org/@types/earcut/-/earcut-3.0.0.tgz",
+      "integrity": "sha512-k/9fOUGO39yd2sCjrbAJvGDEQvRwRnQIZlBz43roGwUZo5SHAmyVvSFyaVVZkicRVCaDXPKlbxrUcBuJoSWunQ==",
+      "dev": true
+    },
     "node_modules/@types/estree": {
       "version": "1.0.6",
       "resolved": "https://registry.npmjs.org/@types/estree/-/estree-1.0.6.tgz",
@@ -1897,6 +1905,11 @@
         "node": ">= 0.4"
       }
     },
+    "node_modules/earcut": {
+      "version": "3.0.1",
+      "resolved": "https://registry.npmjs.org/earcut/-/earcut-3.0.1.tgz",
+      "integrity": "sha512-0l1/0gOjESMeQyYaK5IDiPNvFeu93Z/cO0TjZh9eZ1vyCtZnA7KMZ8rQggpsJHIbGSdrqYq9OhuveadOVHCshw=="
+    },
     "node_modules/eastasianwidth": {
       "version": "0.2.0",
       "resolved": "https://registry.npmjs.org/eastasianwidth/-/eastasianwidth-0.2.0.tgz",