Quote:Original post by hstubbs3
It was a camera "trick" of sorts - the Super NES had "mode 7" to handle the character sprites, scaling and what-not...

Mode 7 was a pseudo-3D thing. You could take a flat map and angle it, turn it, etc. The sprites had to be handled separately - Mode 7 only handled the flat map. At least, as far as I understood it from when we were making games for that platform back then. And I'm not a technical guy.

More accurately, the SNES had several modes in which it could interpret its sprite memory. The machine had a hardware-based tilemap sampler which, given a 3x3 matrix, could transform one graphics layer by said matrix in real-time. The matrix could be changed at each scanline, making things like Axelay's curved perspective possible. This hardware was used by setting the layering mode to "mode 7".

In practice, the hardware probably implement a simple raycaster which calculated the vertical sample coordinates and w only on the first and last vertical line, and interpolated them along each scanline to arrive to final sampling positions.

The SNES emulators Snes9X and ZSnes both implement a very accurate emulation of the aforementioned functionality. Snes9X has source code available, so you can see what they've done.