Link to a topic with its ID

[-FP]

In 3.x IP.Content, I had a custom field for my articles where I stored a topic ID, and then in the article's display template, I set a link to the topic simply adding the ID and a dash, like so "www.site.com/topic/666-", and it would automatically find the topic.

That doesn't work in 4.x, so with the topic ID I have stored, I'm looking for a way to generate the full URL to the topic in the article's display template.

Edit,

I found that I can use ?showtopic=ID... but that doesn't look pretty, how can I generate the actual friendly URL?