Image provided by: Rockin BRockin B has released a Dreamcast VMU demo showing a rotating 3D cube. Here are details:

This demo allows to select one simple 3d model out of 4, apply a couple of 3d transformations (translate, scale, rotate) and to change the CPU frequency (3 speeds).The Tiny 3d Engine itself is capable to draw points, lines and fast polylines, includes 16 bit fixed point arithmetics, a matrix stack, fast matrix multiplication, special transformation functions for translation, scale and rotation, uses a DDA rasterizer, supports clipping, uses a frame (double) buffer.The source code is available for use in other homebrew games.