OrangeCrab Game Console pt. 4 - Sprites

RE: OrangeCrab Game Console pt. 4 - Sprites

javagoza — Mon, 05 Jun 2023 14:24:28 GMT

Nice blog series! Very well explained. I'm looking forward to doing something similar. Thanks!

RE: OrangeCrab Game Console pt. 4 - Sprites

genebren — Thu, 01 Jun 2023 22:36:41 GMT

Sprites are very a very useful tool simplifying motion but a royal pain when you want to have more of a bit mapped memory. Back in the 1990's I wanted to develop a cartridge approach to convert a GameBoy into a handheld instrument. I was eventually able to get my hands on a GameBoy development system and documentation. My attempt to implement a digital scope was thwarted when I learned that the GameBoy utilized a tile and sprite based graphic processor. I eventually built a translation layer that would look like a memory mapped graphics, where writes where translated into tiles, and the tiles were managed to share tiles and release tiles as writes and erases occurred. To test the process, I constructed an etch-a-sketch program to exercise the translation layer. Alas, it took some much time and energy to get this working, that I ran out of time to actually build the handheld instrument. Still it was a blast to play with the systems and it was great learning experience.

Keep up the good work

RE: OrangeCrab Game Console pt. 4 - Sprites

jc2048 — Thu, 01 Jun 2023 10:35:34 GMT

This is good fun. Didn't you want to include the collision detection, or is that still to come?

"Sprites are copied to line buffers!!!"

I didn't know that, though it makes sense for the time that they were originally developed. A full framestore would still have been very expensive on memory, but there was also a limit on the complexity and speed of the logic that could be used in a chip, so doing it on-the-fly without the buffer wouldn't have been possible. The people doing this were probably also familiar with various line-scan methods, like converting vector to line.

Where the balance lies now would depend on the capabilities of the FPGA you were using. Since FPGAs usually have some form of dual-porting on the block RAM, it might be more efficient to have a partial framestore, perhaps a couple of sprites high, and do a 'just-ahead' approach where the sprites get written just ahead of where the scan line is being drawn from.

RE: OrangeCrab Game Console pt. 4 - Sprites

wolfgangfriedrich — Wed, 31 May 2023 17:24:41 GMT

Is one of the colours used as 'transparent flag' to make the non-black background/tile visible instead of the full 16x16 pixel^2 square array of the sprite?

RE: OrangeCrab Game Console pt. 4 - Sprites

michaelkellett — Wed, 31 May 2023 10:12:28 GMT

Great blog - but I can't see the videos.