Wt

Thank you for the test case. Indeed I can reproduce this error.

The reason is that Wt did not perform the test to confirm the presence of webgl. You'd need to pass this manually, or Wt will fall-back to server side rendering.

The attached html file sets the webgl flag for widget set mode.

We use this code to detect WebGL presence in the client:

if (window.WebGLRenderingContext) {
    var canvas = document.createElement("canvas");
    var ctx = null;
    try {
        ctx = canvas.getContext('webgl', {antialias: true});
    } catch (e) {}
    if (ctx == null) {
        try {
            ctx = canvas.getContext('experimental-webgl');
        } catch (e) {}
    }
    if (ctx != null) {
        otherInfo += "&webGL=true";
    }
}

Best regards,

Wim.