I was originally tempted to contact the creator or libdragon, since I noticed that it had no support for rendering triangles. I would love to see an unofficial library doing all the things the official ones can, and in my opinion, it's certainly not out of reach. Even when it comes to the RSP, there is documentation/code detailing the inner workings and architecture.
Anyway, I would love to see some home-brew triangles being rendered on the real N64. Rectangles are boring. Good luck.
Thanks. Sean's hard to get a hold of, but I've been slowly helping him improve the library. Things like not flushing the cache for the entire bitmap when just rendering a single tile (that's now optional under control of a cache control flag), a new timer system written by yours truly that uses the count/compare registers for highly accurate timing, two more resolutions in the display (256x240 and 512x480), and much improved audio. Up next on the block is C++ support (he hasn't added that in yet, though I sent him the changes and a sample C++ app).
Triangle support is the next BIG thing I want in the library. It's really all that keeps libdragon from being used in place of the leaked SDK for many things. Well, triangles and using the RSP for audio mixing and 3D math acceleration.