The Legend of Zelda: Ocarina of Time was a genre-defining release, and it was also a showcase for the graphical power of the Nintendo 64; this was a time when 3D games were incredibly new and exciting. Naturally the project, and Nintendo's work in producing the game engine, was a long time in the works before we got our hands on it. Most famously there's the Shoshinkai 1995 demo, which showed early efforts to create a 3D Link in combat.
Giles Goddard, famous for moving to Tokyo alongside Dylan Cuthbert to assist Nintendo and produce games like Star Fox, did some notable work on visual technology in the N64 era. He created the Mario face that can be manipulated in Super Mario 64, and was also involved in the aforementioned Zelda 64 tech demo that was shown in 1995.
Speaking to MinnMaxShow, he talked a little about source code for the demo that he found in his archives. Intriguingly, he outlines Portal-style effects that he developed on N64, in which Link could view an area through a portal, step through and be transported. Goddard admits that when he saw Portal he recognised an idea he'd had running years earlier, joking he 'should have released it then'.
He explains that the nature of R&D for a project like Ocarina of Time meant the main development team may never have seen the technology in action, or indeed wouldn't have been able to implement it. It's fascinating nevertheless, you can see the interview excerpt below.
It's worth remembering that Giles Goddard and his team at Chuhai Labs are working on an interesting project in the here-and-now, too. He's aiming to create a 'new' 1080° Snowboarding, producing Carve Snowboarding for Oculus VR; it'll be worth keeping an eye on that if you're a VR aficionado.
So, would you have liked to see this portal idea in Ocarina of Time or even Majora's Mask?