A 2D perspective-projected tunnel of triangular tile rings, flown through as they recede toward a vanishing point.
Each ring of triangles sits at a fixed depth (z) around a circular cross-section. Every frame, each vertex is perspective-divided (screen = center + (x,y)/z × focal length) onto the 2D canvas, so near rings spread wide and far rings shrink toward the vanishing point — the same projection math a 3D engine performs on the GPU, done by hand here for every vertex. The camera "flies" by shifting all ring depths forward each frame and wrapping any ring that passes the near plane back to the far end, producing an endless tunnel from a fixed strip of geometry.