fix(Feature2Mesh): fix wrong computing of clockwise polygon.

Compute clockwise in parser

src/Converter/Feature2Mesh.js

@@ -302,10 +302,10 @@ function featureToPolygon(feature, options) {
 
 function area(contour, offset, count) {
     offset *= 3;
-    const n = count * 3;
+    const n = offset + count * 3;
     let a = 0.0;
 
-    for (let p = n + offset - 3, q = offset; q < n; p = q, q += 3) {
+    for (let p = n - 3, q = offset; q < n; p = q, q += 3) {
         a += contour[p] * contour[q + 1] - contour[q] * contour[p + 1];
     }
 
@@ -315,9 +315,6 @@ function area(contour, offset, count) {
 const bottomColor = new THREE.Color();
 function featureToExtrudedPolygon(feature, options) {
     const ptsIn = feature.vertices;
-    const offset = feature.geometries[0].indices[0].offset;
-    const count = feature.geometries[0].indices[0].count;
-    const isClockWise = area(ptsIn, offset, count) < 0;
 
     const normals = feature.normals;
     const vertices = new Float32Array(ptsIn.length * 2);
@@ -345,6 +342,7 @@ function featureToExtrudedPolygon(feature, options) {
         const lastIndice = geometry.indices.slice(-1)[0];
         const end = lastIndice.offset + lastIndice.count;
         const count = end - start;
+        const isClockWise = geometry.indices[0].ccw ?? (area(ptsIn, start, count) < 0);
 
         coordinatesToVertices(ptsIn, normals, vertices, z, start, count);
         fillColorArray(colors, count, bottomColor, start);
@@ -365,13 +363,23 @@ function featureToExtrudedPolygon(feature, options) {
             indices[startIndice + i] = triangles[i] + startTop;
         }
 
-        for (const indice of geometry.indices) {
+        // add extruded contour
+        addExtrudedPolygonSideFaces(
+            indices,
+            totalVertices,
+            geometry.indices[0].offset,
+            geometry.indices[0].count,
+            isClockWise);
+
+        // add extruded holes
+        for (let i = 1; i < geometry.indices.length; i++) {
+            const indice = geometry.indices[i];
             addExtrudedPolygonSideFaces(
                 indices,
                 totalVertices,
                 indice.offset,
                 indice.count,
-                isClockWise);
+                !(indice.ccw ?? isClockWise));
         }
 
         if (batchIds) {

src/Parser/GeoJsonParser.js

@@ -25,6 +25,9 @@ function readCRS(json) {
 }
 
 const coord = new Coordinates('EPSG:4978', 0, 0, 0);
+const last = new Coordinates('EPSG:4978', 0, 0, 0);
+const first = new Coordinates('EPSG:4978', 0, 0, 0);
+
 // filter with the first point
 const firstPtIsOut = (extent, aCoords, crs) => {
     coord.crs = crs;
@@ -43,6 +46,24 @@ const toFeature = {
         }
         geometry.updateExtent();
     },
+    // compute clockwise polygon
+    populateGeometryWithCCW(crsIn, coordinates, geometry, feature) {
+        geometry.startSubGeometry(coordinates.length, feature);
+        coord.crs = crsIn;
+
+        let sum = 0;
+        first.setFromValues(coordinates[0][0], coordinates[0][1], coordinates[0][2]);
+        last.copy(first);
+        for (var i = 0; i < coordinates.length; i++) {
+            coord.setFromValues(coordinates[i][0], coordinates[i][1], coordinates[i][2]);
+            sum += (last.x - coord.x) * (last.y + coord.y);
+            last.copy(coord);
+            geometry.pushCoordinates(coord, feature);
+        }
+        sum += (last.x - first.x) * (last.y + first.y);
+        geometry.getLastSubGeometry().ccw = sum < 0;
+        geometry.updateExtent();
+    },
     point(feature, crsIn, coordsIn, collection, properties) {
         this.default(feature, crsIn, [coordsIn], collection, properties);
     },
@@ -68,7 +89,7 @@ const toFeature = {
 
         // Then read contour and holes
         for (let i = 0; i < coordsIn.length; i++) {
-            this.populateGeometry(crsIn, coordsIn[i], geometry, feature);
+            this.populateGeometryWithCCW(crsIn, coordsIn[i], geometry, feature);
         }
         feature.updateExtent(geometry);
     },