A recreation of the Amiga Boing! demo for NES, and also the Atari ST BOINK.
More info about this project: Patreon article
Download ROM: Releases
- Left - decrease spin rate
- Right - increase spin rate
- Up - increase bounce height
- Down - decrease bounce height
- Select - toggle Atari ST BOINK / Amiga Boing! mode
- Start - credits
- B - TV pixel aspect ratio
- A - square pixel aspect ratio
Download cc65 (Windows Snapshot) and place it in a cc65 folder in this directory.
Run build.bat to build the ROM to temp/boing.nes.
This program uses a reduced subset of the cc65 C runtime library. This is pre-built, but if you wish to rebuild it, download the libsrc folder from the cc65 source code and place it in this directory, and run build_runtime.bat. This will rebuild temp/runtime.lib. (See batch file for more information.)
The graphics data can be rebuilt with build_gfx.py. This converts several PNG images in the gfx folder into data for the build, placed in the temp folder. This script requires Python 3 with PIL.
These tools can also be run on other operating systems, but you would have to duplicate the batch scripts in a format suitable for your OS.
This project was partly intended as a simple C example for NES development, and something I might use as a starting point for later projects. It's sort of a continuation of my earlier NESert Golfing project, but trying to provide for more "normal" NES needs.
It contains an assembly framework for normal NES operations which can be accessed from C. You can see the contents of this library declared at the top of boing.c. The assembly implementation appears in boing.s.
For the most part, all code related to the Boing demo was in C, contained in boing.c and the assembly file boing.s is almost entirely just the NES library code, except for a little bit of data layout stuff.
Basic NES library functions:
- NES ROM and header generation
- Tools for generating nametable and sprite data (build_gfx.py)
- Rendering control and PPU data uploading
- Sprite drawing
- Simple sound effect engine
- Gamepad input
The C runtime library provided is very minimal. It contains only what is needed to support cc65's generated C code. The C standard library is not included, so including most C library headers (e.g. string.h) will probably not be useful here.
The sprite generator looks for redundant horizontal and vertical flipped tiles and tries to reuse them. For this demo it also has an additional redundancy check that swaps the red-white ball tiles for white-red, but for a more generic use this should be removed. Look for "palette shifted" in the comments of build_gfx.py to find the adjustment.
This project used a CNROM mapper configuration, just so it could fit the ball graphics in two aspect ratios, but boing.cfg can be modified for other mappers. In particular the CHR memory regions and TILES segments, and possibly the DPCM segment could be removed or relocated if you need more space for sound samples. The NES header will also need a small edit, found at the bottom of boing.s.
There is a test of NES library features that weren't otherwise used in boing.nes accessed by pressing Select + Start.
This source code is provided under the Creative Commons Attribution license. (CC BY 4.0)
Full details of this license are available here: https://creativecommons.org/licenses/by/4.0/
This approximately means that you are free to reuse this source code for your own purposes, provided that you include an attribution to me (Brad Smith) in documentation and accessible credits for the work it is used in.
