How does X2:Megablast parallax with all that colors?

[Tigerskunk]

Usually, it's completely obvious to me how Amiga games use their playfields (or not), but in this case, I am really wondering how it was done



Megablast does parallax with 4 colours in the background layer and 16 colours in the front out of a total of 16 colours palette.

Anyone any idea how they were able to accomplish this?

[Galahad/FLT]

Sacrifice of smoothness and speed. Xenon 2 doesnt remotely run close to 50frames a second at anytime, and suffers horrific slowdown when it gets busy.

[Tigerskunk]

So they were drawing all that stuff unto the screen all the time?

[Galahad/FLT]

Originally Posted by Steril707

So they were drawing all that stuff unto the screen all the time?

Looks like it.

The height of the actual gamescreen where all the action happens (not including the score line) is only 190 lines in height, so right away, a typical Atari ST screen height is 200, so thats 10 lines saved, and a usually typical Amiga screen should be 256 in height, so thats 66 horizontal lines Xenon 2 doesn't have to redraw.

Whilst the music in the Amiga version is better, the game is designed around what the Atari ST was able to do, and then minor improvements under the hood for the Amiga version.

It uses a double buffer setup, it doesn't simply add to the bitplane pointers to perform its scroll either, everything is being redrawn.

The starfield is curiously not a sprite starfield, its actually blitted objects, which seems remarkably wasteful.

Lots of black space is prevalent throughout the game, and it obviously never remotely gets close to being smooth scrolling either.

The background layer is also being redrawn every other frame, so that it appears to scroll at a different rate, which means every other frame, the game has less redrawing to do, other than restoring for when bullets an enemies cross over.

The crap collision detection can't be a mistake, i'm sure its by design as well.

Coupled with it being in only 16 colours, and doesn't sideways scroll, its why it can get away with so much redrawing, but its the design of the game that allows it to get away with so much.

For instance, play the first level and its quite busy, partway through and you get those worm enemies that have quite a lot of moving parts, noticeably there are now less 'foreground' graphics to plot whilst these are onscreen, and when theres less worms onscreen, then there is now more foreground graphics coming back into view again.

The weapons are also designed in such a way as to try and minimise the overheads. You start off with a smaller weapon but it fires lots of shots onscreen. As soon as you get the side rocket launcher, the fire rate is now noticeably slowed down, so when you upgrade that weapon, it then speeds upto the same as the initial weapon but without necessarily slowing the game down too much. A bit like the psychological effect of Super Hang On where you get the impression you're going faster because the bike engine noise says you are, but the actual game isn't moving any faster at all.

Xenon 2 still looks great inspite of its 16 colour graphics (a testament to Marc Colemans skills), but its not programmed with the Amiga in mind at all.

[rsn8887]

Thank you Galahad for a great analysis and OP for a great topic!

Personally, I could never stand the jerkiness of Xenon 2 on the Amiga. Even as a child it bothered me to no end.

Their later titles Gods and Chaos Engine are masterpieces though. I like how the jerkiness on those games actually makes them better (because slower).

[Minuous]

Doesn't even look great IMHO, it's all just different shades of brown and black. Horrible.

[roondar]

Thanks for that analysis!

I must admit I'm halfway surprised it actually uses the blitter, I was kind of expecting it not to do so because of the really slow screen updates.

[Tigerskunk]

Thanks for the indepth analysis.
Really weird that they went for drawing all stuff on the screen all the time.

On the other side, that gives that game a rather unique look.

[roondar]

Originally Posted by Steril707

Thanks for the indepth analysis.
Really weird that they went for drawing all stuff on the screen all the time.

On the other side, that gives that game a rather unique look.

Well, in some cases you might want to do so. If drawing the whole screen is faster than drawing all the separate parts, it is actually a good idea. Thing is though that the 16 bit home computers (Amiga & Atari ST) where not actually fast enough to do so at 50Hz (or even 25Hz) - especially when also having to deal with the rest of the game.

A good example of the same technique - though without parallax scrolling - can be found in Blood Money, it updates the screen every three frames (if I read what the developer wrote about this correctly anyway). It does this to allow for bigger and more enemies on screen.

This, however, does not change that IMHO Xenon 2 is overrated for it's technical achievements, it runs very slow indeed and that detracts from the gameplay.

[Thorham]

Originally Posted by Minuous

Doesn't even look great IMHO, it's all just different shades of brown and black. Horrible.

Really? I must be colorblind then

[s2325]

In old times I thought slowdowns in Xenon 2 are for less skilled gamers as there was so much sh*t on screen.

[Amigajay]

Originally Posted by roondar

This, however, does not change that IMHO Xenon 2 is overrated for it's technical achievements, it runs very slow indeed and that detracts from the gameplay.

Bitmap games were more technical marvels on the Atari ST compared to the Amiga as most of them were designed with the ST hardware in mind then enhanced for the Amiga, bar the Chaos Engine which was designed for the Amiga first and foremost if i remember.

The music on Xenon II was a technical marvel on the Amiga at the time, the game not so much!

[Tigerskunk]

Originally Posted by roondar

A good example of the same technique - though without parallax scrolling - can be found in Blood Money, it updates the screen every three frames (if I read what the developer wrote about this correctly anyway). It does this to allow for bigger and more enemies on screen.

Interesting. I read somewhere, though, that they also employed that "double screen scrolling technique". Why would they need that then, if they redraw everything all the time?

Blood Money always looked weird to me. Something that was off that I couldn't grasp. Guess that was the jerky scrolling, then (and, looking at a long play on youtube right now, the player sprite looks like out of a different game, style wise. )...

[DanScott]

Originally Posted by Amigajay

The music on Xenon II was a technical marvel on the Amiga at the time, the game not so much!

Nahh, it was pretty poor... just a few samples strung together.. nothing special at all

Overall Xenon 2 was a pretty poor game... some of the graphics were nice, but technically it was nothing special..

[Amigajay]

Originally Posted by DanScott

Nahh, it was pretty poor... just a few samples strung together.. nothing special at all

Overall Xenon 2 was a pretty poor game... some of the graphics were nice, but technically it was nothing special..

Well all Amiga music is samples strung together! But the fact they got the quality of samples and length of song into the game was what it made it great.

[Tigerskunk]

I think the awesome thing about it was that it was a Bomb The Bass track (with that famous Carpenter "Assault"-theme) when BtB was the hottest shit.

As an Amiga track generally, it's not really that special.

[nogginthenog]

Indeed. I think it one of the first games to use a commercial 'pop' track.

[Master484]

I remember the days when Xenon 2 was released, Finnish game magazines praised it, and called it the best shooter for the Amiga.

I think it was the combination of the music + all the powerups that allowed you to fill the screen with bullets + the talking space alien in the weapon shop, that together created the "wow effect". The somewhat jerky 17 fps screen update rate didn't seem to bother people so much, because the game itself was so "badass". I think one reviewer wrote that the powerups give you a feeling of power, that was missing from most other shooters.

Also it's good to remember that back then in 1989 many people were still using the C64 and other 8-bit computers, and any Amiga game that was released was also compared to the best games that the C64 had to offer. And a game like Xenon 2 really instantly showed what the Amiga can do, and C64 can't: screen full of bullets, big, good looking graphics, 3 layers of parallax, and "real" music from a real band.

Games like these were a good reason to buy an Amiga. Imagine being a C64 owner, and seeing Xenon 2 on a friends house, and then going back to your C64...all those great C64 shmups like Armalyte and Sanxion suddenly didn't feel so good anymore.

---

And even today, technically Xenon 2 is still quite interesting. If it indeed blits all the gfx to the screen every frame, and doesn't use hardware scrolling or sprites, then this means that it does a huge number of blits, both big and small, actually reaching "bullet hell" object amounts with maximum powerups, and still maintains a reasonable smooth update rate of 17 fps ( = display updated every 3rd frame ), or at least tries to maintain it.

Also it shows that a two layer parallax background is possible, without using dual playfield mode. So if we would add sprites to the game, maybe something cool like a 3rd parallax layer could be done with them, without losing any of the "speed"?

Or maybe we could actually turn on Dual Playfield mode, and have 6 layers of parallax: each Playfield could have one hardware scrolled layer, and one layer above it created with blits, so it would be 2 scrolling layers per playfield + a sprite layer between the playfields + the star layer at the bottom. And with some luck it might still run at 17 fps. And of course AGA could do 16 + 16 color playfields, if 8 + 8 wouldn't look good. Xenon 2 - "Bomb the Blitter" Special Edition?

And even if that would be impossible, then at least the Player's ship could have been made with sprites; Blood Money too runs at 17 fps, but the Player's ship is a sprite and it moves at 50 fps, which gives the action an impression of smoothness.

In some other threads there have been discussions on how to do a "bullet hell" shooter on Amiga; and maybe the answer is "Xenon 2 on steroids": take the design of Xenon 2, but make player with sprites, hardware scroll at least one of the background layers so that more blitting power is saved for the game objects, and update everything in the display only every 3rd frame, except the Player sprite which can move at 50 fps. I think most arcade coin-op shooters should be possible on the Amiga with this design.

[sandruzzo]

Originally Posted by Master484

I remember the days when Xenon 2 was released, Finnish game magazines praised it, and called it the best shooter for the Amiga.

I think it was the combination of the music + all the powerups that allowed you to fill the screen with bullets + the talking space alien in the weapon shop, that together created the "wow effect". The somewhat jerky 17 fps screen update rate didn't seem to bother people so much, because the game itself was so "badass". I think one reviewer wrote that the powerups give you a feeling of power, that was missing from most other shooters.

Also it's good to remember that back then in 1989 many people were still using the C64 and other 8-bit computers, and any Amiga game that was released was also compared to the best games that the C64 had to offer. And a game like Xenon 2 really instantly showed what the Amiga can do, and C64 can't: screen full of bullets, big, good looking graphics, 3 layers of parallax, and "real" music from a real band.

Games like these were a good reason to buy an Amiga. Imagine being a C64 owner, and seeing Xenon 2 on a friends house, and then going back to your C64...all those great C64 shmups like Armalyte and Sanxion suddenly didn't feel so good anymore.

---

And even today, technically Xenon 2 is still quite interesting. If it indeed blits all the gfx to the screen every frame, and doesn't use hardware scrolling or sprites, then this means that it does a huge number of blits, both big and small, actually reaching "bullet hell" object amounts with maximum powerups, and still maintains a reasonable smooth update rate of 17 fps ( = display updated every 3rd frame ), or at least tries to maintain it.

Also it shows that a two layer parallax background is possible, without using dual playfield mode. So if we would add sprites to the game, maybe something cool like a 3rd parallax layer could be done with them, without losing any of the "speed"?

Or maybe we could actually turn on Dual Playfield mode, and have 6 layers of parallax: each Playfield could have one hardware scrolled layer, and one layer above it created with blits, so it would be 2 scrolling layers per playfield + a sprite layer between the playfields + the star layer at the bottom. And with some luck it might still run at 17 fps. And of course AGA could do 16 + 16 color playfields, if 8 + 8 wouldn't look good. Xenon 2 - "Bomb the Blitter" Special Edition?

And even if that would be impossible, then at least the Player's ship could have been made with sprites; Blood Money too runs at 17 fps, but the Player's ship is a sprite and it moves at 50 fps, which gives the action an impression of smoothness.

In some other threads there have been discussions on how to do a "bullet hell" shooter on Amiga; and maybe the answer is "Xenon 2 on steroids": take the design of Xenon 2, but make player with sprites, hardware scroll at least one of the background layers so that more blitting power is saved for the game objects, and update everything in the display only every 3rd frame, except the Player sprite which can move at 50 fps. I think most arcade coin-op shooters should be possible on the Amiga with this design.

What about this for Aga? Working on it?

http://amigaonex.blogspot.it/2016/09...f-star_30.html

[Amigajay]

Originally Posted by sandruzzo

What about this for Aga? Working on it?

http://amigaonex.blogspot.it/2016/09...f-star_30.html

That looks awesome! Is that your blog Sandruzzo?