SkillGrid - new AGA game in the works

[4pLaY]

Congrats, i might have to get this one when its released.

[saimo]

Originally Posted by 4pLaY

Congrats, i might have to get this one when its released.

Thanks, nice to hear

[vulture]

Great news! Can't wait to get my hands on it!

[saimo]

@vulture




@all

If you're curious about how the scrolling works, this video is for you:

[ Show youtube player ]

To fully appreciate it, please read the technical details below. Please note that some knowledge of the Amiga hardware is required.

Given that about 80% of the RAM that the standard Amiga 1200 and CD³² are equipped with is allocated for music (which is not standard tracker modules, but conceptually MP3-like as detailed in this article), SkillGrid uses a number of tricks to fit all the rest (code, graphics, and sound effects) in the remaining memory. Some of them are shown in this video.

The background is made of three parallax-scrolling layers:
* the bottom layer consists of a bitmap that is much taller than the screen;
* the other two layers are rendered dynamically by blitting graphic tiles as needed - this is necessary to have graphics change all the time and, at the same time, allows virtually endless layers at the small cost of the memory taken by the tiles graphics;
* the two layers are not buffered, but are just slightly taller than the screen: the incoming tiles are rendered in the out-of-screen areas, thus hiding the drawing process to the eye (with buffering, almost twice the RAM would have been needed, instead);
* all the layers are wrapped around in real time by the Copper (as explained in the next paragraph); this mechanism allows the layers to occupy exactly the amount of RAM needed by the graphics (i.e. no extra RAM is required for the twin copies otherwise necessary to smoothly restart scrolling when a layer has scrolled entirely).

The layers wrap-around trick is implemented like this:
* the line that a layer starts to display from at the top of the screen can be any (for exampe, if a layer is 300 lines tall, any line between 0 and 299 can be the line displayed at the very top of the screen); this is obtained by telling the Lisa chip (through the BPLxPT registers) that the bitplanes of the layer start at the addresses corresponding to the chosen line;
* if/when the bitplanes of the layer are entirely displayed but the screen has not been entirely redrawn yet, the Copper writes on the fly the addresses of line 0 to the BPLxPT registers (for example, if the topmost line was 280, when the 20th visible line of the screen has been drawn the bitplanes bottom has already been reached, but there are still 256-20 = 236 screen lines to draw, so the Copper brings the bitplanes addresses back to the very beginning; the result is that the bottom of the bitplanes is visually followed by their top);
* therefore, the Copper has to continuously wait for the screen line(s) where it is necessary to reset the BPLxPT registers and then perform the writes; normally only one layer per line needs to be wrapped around, but, depending on the position of the layers, occasionally two or even three layers end on the same line and thus have to be wrapped around at the same time;
* the Copper code (Copperlist) that performs such operations is generated by the CPU every frame after the screen has been drawn entirely, according to the current scrolling position.

In the first part of the video:
* the blue layer is the bottom layer (layer 0);
* the green layer is the middle layer (layer 1);
* the red layer is the top layer (layer 2);
* the lines marked with T0/T1/T2 indicate the top of layer 0/1/2;
* the lines marked with B0/B1/B2 indicate the bottom of layer 0/1/2.

It is worth noting that since the tiles of the top layer are hexagons, they are vertically shifted by half a hexagon every other column. As a consequence, the bottom row tiles in the odd columns actually need to have the upper half blitted at the bottom of the layer, and the bottom half at the top of the layer. Due to the fact that the layer is made of two bitplanes, up to four separate blits might be necessary to render a tile.
In the second part of the video, these tiles are those that are crossed by the horizontal line that marks where the layer wraps around.

[Puggsy]

That is very interesting, thanks for sharing!
But why is the music taking up such a big space? Can it not be optimized?

Just curious as to what else you could do to the game had you more memory to play with!

[saimo]

Originally Posted by Puggsy

That is very interesting, thanks for sharing!
But why is the music taking up such a big space? Can it not be optimized

The answer is in the post Music "is not standard tracker modules, but conceptually MP3-like as detailed in this article". Like for gameplay and graphics, I decided to do something totally different.

[saimo]

Little Christmas gift: preview of the inlay that will grace the RGCD package!


click to enlarge

The package will include a CD, a nice manual, a few surprises and, optionally, also two floppies. The CD can be used to play the game on the Amiga CD³² and also to install the game on the Amiga 1200/4000; moreover, it contains also the ADF images of the floppies.
To be released (hopefully) in Q1 2019.

https://www.retream.com/SkillGrid

[saimo]

One more little gift: this medley will let you enjoy the music that will rock your Amigas!

https://soundcloud.com/retream/skillgrid-medley

[saimo]

@Amigajay

You're welcome!


@all

The first draft of the manual is done! Now it's only a matter of fixing the errors (if any) and changing a name...


click to enlarge

The manual will consist in a 16 pages jewel case booklet, as the game CD will come in a jewel case inside a gorgeous clamshell box.

[saimo]

For the joy of all the AmigaCD³² consoles out there, here's the initial design of the CD:


click to enlarge

Actually, the CD contains also the ADF images of the floppies and a pre-installed copy of the game for A1200s and A4000s

[NeoHippie2016]

Cool!

[saimo]

@NeoHippie2016

Thanks!


@all

The design of the floppy labels has been kept intentionally simple. It might still change, but probably won't be much different from what shown in this mockup.


click to enlarge

[4pLaY]

The design looks nice saimo .

[saimo]

@4pLaY


Thanks



@all


The CD jewel case tray inlay is now done, too.


(click to enlarge)

[saimo]

Just a quick note to let you know that I've started posting the pages from the manual so that you can learn the game details even before it hits the shelves. Every day I'll post a new page on the Facebook, Twitter, Patreon, and itch.io pages of RETREAM - if you're curious, just head over there (they're all publicly accessible, even without account)

[saimo]

Here's a massive gameplay video that will let you see what you have read in the manual - and it shouldn't be too long until you can also experience it

[ Show youtube player ]

Don't think the game is crazy: you haven't played it yet to fully appreciate its madness

https://www.retream.com/SkillGrid

[vulture]

Oh man, looks and sounds fantastic!

[StingerHU]

Excellent work dude, i really love to see actual games like this one in Amiga Voted!

[saimo]

Thanks, guys!

[Neil79]