WebGL SSR rendering

CSR is Client Side Render
- The content on the page is rendered by the JS file we loaded, which runs on the browser, and the server only returns an HTML template.
SSR is short for Server Side Render
- The content on the page is rendered by the server, and the browser simply displays the HTML returned by the server.
- Server-side rendering, where the rendering process is implemented on the server and then streamed to the front end as a video stream, is similar to Pixel Streaming in Unreal Engine 4.