in modules/layers/src/mode-handlers/extrude-handler.ts [227:244]
getPointForPositionIndexes(positionIndexes: number[], featureIndex: number) {
let p1;
const feature = this.getImmutableFeatureCollection().getObject().features[featureIndex];
const coordinates: any = feature.geometry.coordinates;
// for Multi polygons, length will be 3
if (positionIndexes.length === 3) {
const [a, b, c] = positionIndexes;
if (coordinates.length && coordinates[a].length) {
p1 = coordinates[a][b][c];
}
} else {
const [b, c] = positionIndexes;
if (coordinates.length && coordinates[b].length) {
p1 = coordinates[b][c];
}
}
return p1;
}