OL-Cesium error

Question

I'm trying to implement my map using OL-Cesium / CesiumJS.

var layer2 = new ol.layer.Tile({
      source: new ol.source.TileWMS({
        url: 'https://demo.boundlessgeo.com/geoserver/wms',
        params: {
          'LAYERS': 'opengeo:countries'
        }
      })
});

var map = new ol.Map({
    layers: [
        layer2
    ],
    target: 'world-map',
    view: new ol.View({
        center: [-99.816397,43.2843246],
        zoom: 4,
        projection: 'EPSG:4326'
    })
}); 

var ol3d = new olcs.OLCesium({map: map});
var scene = ol3d.getCesiumScene();
ol3d.setEnabled(true);

This is working well and I can see my map as a globe. But when I change the layer to my local OpenStreetMap Geoserver ...

var osm = new ol.layer.Tile({
    source: new ol.source.TileWMS({
      url: 'http://my.local.osm/geoserver/wms',
      params: {
          'LAYERS': 'osm:worldlayer',

      },
    })
}); 

... I can see only a white globe. Inspecting the "network traffic" in my browser I can see all tiles are comming fine.

This is one of the tile URL in my local geosever (from the browser traffic inspector) :

http://my.local.osm/geoserver/osmope/wms?SERVICE=WMS&VERSION=1.3.0&REQUEST=GetMap&FORMAT=image%2Fpng&TRANSPARENT=true&LAYERS=osm%3Aworldlayer&WIDTH=256&HEIGHT=256&CRS=EPSG%3A4326&STYLES=&BBOX=39.375%2C-123.75%2C45%2C-118.125

and this is one of the tiles URL from working Boundless demo geoserver

https://demo.boundlessgeo.com/geoserver/wms?SERVICE=WMS&VERSION=1.3.0&REQUEST=GetMap&FORMAT=image%2Fpng&TRANSPARENT=true&LAYERS=opengeo%3Acountries&WIDTH=256&HEIGHT=256&CRS=EPSG%3A4326&STYLES=&BBOX=22.5%2C-135%2C45%2C-112.5

Both cases I can see the image thumbnail in the browser network inspector and the HTTP result is 200. The error (is not a CORS error):

An error occurred in "mf": Failed to obtain image tile X: 4 Y: 2 Level: 3. Cesium.js:459:3692

I'm using OL-Cesium v1.37 from GitHub

There is no proxy between me and my OSM geoserver. There is a proxy between me and Internet.

Answer 1

Well this is a CORS error at all.

Solved (at least at my own server) editing the web.xml of my Tomcat at <TOMCAT_DIR>/conf/web.xml and added this:

<filter>
  <filter-name>CorsFilter</filter-name>
  <filter-class>org.apache.catalina.filters.CorsFilter</filter-class>
</filter>
<filter-mapping>
  <filter-name>CorsFilter</filter-name>
  <url-pattern>/*</url-pattern>
</filter-mapping>

... but I think OL-Cesium is not very useful when using external layers from Geoserver. OpenLayers can show any WMS layer with easy. Most of my user's layers I can't show in Cesium globe because CORS.