Okay, Can someone explain how Rescue On Fractalus was done on the 7800?

[fultonbot]

How could Rescue On Fractalus be created on purely bitmapped engine?  

What am I missing?

 

AtariProtos.com - All Your Protos Are Belong To Us!

Atari 7800 Rescue On Fractalus - YouTube

[+SmittyB]

The 7800 can be made to draw a bitmap quite easily compared to other consoles and some microcomputers thanks to the way it doesn't have a traditional tilemap+sprites display. Essentially you just draw a couple of wide objects and tell them to get their graphics data from some place in RAM instead of ROM, but the limiting factor is that the 7800 doesn't have much RAM so requires extra on the cartridge.

 

If you look at the graphics in the 3D section there are only ever 4 colours - the background sky, the light brown, dark brown, and the green for the alien guns. All that fits in a single 160A mode palette.

 

As for how the rendering is actually done I can only guess. I think the game takes a semi-randomised grid specifying a height at each vertex, works out how far along the closest gridline a given column of pixels represents, then to draw it it writes to the bitmap with the dark brown colour from the bottom upwards until it hits the height as specified based on the grid and the camera then draws a light bit, then moves onto the section of grid behind it.

I think it's basically a low-resolution voxel engine with a lot of interpolation and some controlled randomisation to create the jagged mountains.

[RevEng]

One more wrinkle worth mentioning... RoF uses a half-vertical resolution bitmap (i.e. squarish 160 mode pixels) which cuts down on number of pixels it needs to thrown on the screen. The 7800 doesn't have such a mode, but the on-cart ram has an address line pulled down permanently, so that each odd graphics memory page maps to the prior even page. (aka "mirror ram") Thanks to the way 7800 graphics blocks are laid out, this turns the higher res mode into half-resolution.

[John Stamos Mullet]

Short answer:

 

It wasn't. It never made it to production.

[+Karl G]

13 hours ago, John Stamos Mullet said:

Short answer:

 

It wasn't. It never made it to production.

I'm not sure how this is relevant? It's an existing prototype, and figuring out how it was coded is certainly a worthwhile topic, IMO.

[John Stamos Mullet]

1 hour ago, Karl G said:

I'm not sure how this is relevant? It's an existing prototype, and figuring out how it was coded is certainly a worthwhile topic, IMO.

I didn't say the subject wasn't a worthwhile topic to discuss. I was not trying to dissuade people from discussing it, at all.

 

I just noted that what does exist is a very incomplete proto, and was never a game that was released; so asking "how it was done" is a bit of a misnomer, since it wasn't ever really "done", in the literal sense.

 

While it might be neat to investigate how certain functions were performed in the code (if the code exists, I don't know), I would think this might fall under examples of what not to do, since they never really got far enough to make a working beta.

 

[R_Leo_1]

Very pedantic response but okay.

[RevEng]

On 9/14/2021 at 11:59 AM, John Stamos Mullet said:

While it might be neat to investigate how certain functions were performed in the code (if the code exists, I don't know), I would think this might fall under examples of what not to do, since they never really got far enough to make a working beta.

It's not playable beyond steering the ship, but it works very well to show off the tech proof-of-concept. Spectacularly well, in my estimation. 

 

What lesson do you think it can teach developers, as far as "what not to do"?

 

[Trebor]

The "what not to do" lesson to be learned from this prototype is work for a company that lacks the ability to provide the resources needed to develop the requested game.

 

RoF used 2KB of cart RAM when development was first started in '84.  It was shelved along with the console.  When things picked up again for the 7800 in the later 80's, it wasn't given the go ahead to finish development.

 

In comparison, the games Jinks and Impossible Mission were provided 8KB RAM.  Summer and Winter Games were provided 16KB.

 

Considering what was pulled off with as little as 2KB RAM, this game would have been more than "done" with 16 or even 8KB.

[John Stamos Mullet]

7 hours ago, RevEng said:

It's not playable beyond steering the ship, but it works very well to show off the tech proof-of-concept. Spectacularly well, in my estimation. 

 

What lesson do you think it can teach developers, as far as "what not to do"?

 

I mean - most of the graphics are just being displayed in random or cycling order. They aren't tied to any interactive game logic. Someone with enough time on their hands could look into how to write text and graphics to the display for a 7800 and put something similar together. There's a chasm of difference between repeated cycling of the same graphics
 and text, and actually tying that to working game logic that functions smoothly. I'm not trying to say what was produced here was "easy" by any means. But looking at what was done with games like f-18 hornet, and Super Huey, its' not like it was some "wow" technological achievement for the platform either. Just a bummer that it's another abandoned project on an underutilized console.

15 hours ago, R_Leo_1 said:

Very pedantic response but okay.

Edited September 16, 2021 by John Stamos Mullet

[RevEng]

7 hours ago, John Stamos Mullet said:

I mean - most of the graphics are just being displayed in random or cycling order. They aren't tied to any interactive game logic. Someone with enough time on their hands could look into how to write text and graphics to the display for a 7800 and put something similar together. There's a chasm of difference between repeated cycling of the same graphics
 and text, and actually tying that to working game logic that functions smoothly. I'm not trying to say what was produced here was "easy" by any means. But looking at what was done with games like f-18 hornet, and Super Huey, its' not like it was some "wow" technological achievement for the platform either. Just a bummer that it's another abandoned project on an underutilized console.

By random graphics, I'm assuming you're talking about the cockpit display here. It's best practice to rough-in everything you need to display, to ensure you won't actually blow the dma budget. Actually making the displays do something, even random or cycling, prior to a fleshed out game is a good way to fire-up people's imaginations for show-and-tell. I see a whole lot of "what to do" in your critique choice here.

 

On your broader point about it not being finished, it's a proto. We all know what that means. As Trebor already highlighted, the only lesson in "what not to do" is not have Jack Tramiel calling the shots on your project, if it requires anything more than base hardware.

[John Stamos Mullet]

1 hour ago, RevEng said:

By random graphics, I'm assuming you're talking about the cockpit display here. It's best practice to rough-in everything you need to display, to ensure you won't actually blow the dma budget. Actually making the displays do something, even random or cycling, prior to a fleshed out game is a good way to fire-up people's imaginations for show-and-tell. I see a whole lot of "what to do" in your critique choice here.

 

On your broader point about it not being finished, it's a proto. We all know what that means. As Trebor already highlighted, the only lesson in "what not to do" is not have Jack Tramiel calling the shots on your project, if it requires anything more than base hardware.

No disagreement on Tramiel, for sure. As much as I love the 7800, both nostaligia-wise, and for the homebrew resurgence of it, I still have deep seated trauma from all the games we were promised that never showed up. This one, Skyfox, etc. Hell - by the time One on One arrived in a store anywhere near me, I was already playing other consoles.

[fultonbot]

On 9/14/2021 at 8:59 AM, John Stamos Mullet said:

 

I just noted that what does exist is a very incomplete proto, and was never a game that was released; so asking "how it was done" is a bit of a misnomer, since it wasn't ever really "done", in the literal sense.

 

"done" as in the fractal landscape.