The examples guard against building if their dependencies are not met. If that example is important, yes, you’ll need to enable the VTK::RenderingContextOpenGL2 and VTK::RenderingGL2PSOpenGL2 modules in your build and rebuild VTK. However, that issue indicates that the required module doesn’t work with Emscripten, so it just isn’t available for 9.0.3. If it gets resolved in time for 9.1, then that’s when it will be available again.