Outrun AGA

[saimon69]

DJ metune strikes again! You will need some software mixing there for the effects, though, IF you want some in the game together with the music... that or a reduction to three channel plus some en passant over the music

[saimon69]

By the way, once the engine is done, will be possible to create other games with it? A decent road engine can open possibilities!

[pink^abyss]

Originally Posted by agermose

Some technical details for the interested.

The arcade has many gfx layers:
Road 0, road 1. Priority can be changed.
2 tile layers, used for horizon gfx.
Sprites (128).
Character layer.
Screen size 320x224, framerate 30 fps.

Main CPU (68K at 12.5 MHz) runs the main game code. The secondary CPU (68K at 12.5 Mhz) takes care of creating data for the road HW. Then there is a sound CPU (z80).
Custom HW for road generation, sprite scaling, HW scrolling etc.


The main 2 challenges are the road generation and the sprite engine.


Technical details for the Amiga version, subject to change.
AGA base HW, PAL only.

AGA dual playfield, 4 bitplanes each.
Screen size 288x224. FMODE4 bitplane fetch.
Playfield 1 is used for road 0, (and horizon gfx later).
Amiga HW sprites are used for road 1. FMODE4 used for 64 pixel sprites.
Playfield 2 is used for the sprite, and text layers. Only the Ferrari sprite is there at the moment.

The main and secondary CPU code has been disassembled from ROM, and modified for use in the Amiga version. The single Amiga CPU (68020 at 14.2 MHz on A1200) runs the code from both CPU's, sequentially. The MAME debugger is really helpful, to get the code right. I have also looked at Cannonball (by Chris White) code, for the code I'm unsure of what it does.

The road display code, simulating the custom road HW of the arcade, is optimized heavily for AGA hw, and uses very few resources. Big thanks to legendary MAME developer Aaron Giles, for reverse engineering the Outrun arcade HW.

Sound is done using a MOD player at the moment.

The sprite engine is the next big task.
Getting all the sprites into 15 simultaneous colours (PF2) will be a major challenge. As will scaling the sprites, without excessive memory usage, and keeping a high framerate.

What about AHX sound

https://soundcloud.com/pink_abyss/ma...d-shower-cover


Just kidding, mod music can be more accurate than this..

[agermose]

Originally Posted by dlfrsilver

How many colors do you plan to make the game with ?

There is no fixed number of colours as such.

Tile backgrounds, horizon gradient, and the road stripes will all be very close to the arcade colour wise.

The sprites have to share 15 colours of playfield 2, the Ferrari alone has 14 colours.
Some colour changes may be possible to get more than 15 simultaneous colours, but the hw sprites are not limited to a range of scanlines, but span the entire height of the playfield.

[agermose]

Originally Posted by saimon69

DJ metune strikes again! You will need some software mixing there for the effects, though, IF you want some in the game together with the music... that or a reduction to three channel plus some en passant over the music

The music in the demo is actually 2 channels only!
Uses too much memory though, so some adjustments are needed.

[agermose]

Originally Posted by saimon69

By the way, once the engine is done, will be possible to create other games with it? A decent road engine can open possibilities!

Yes it would be possible, but the benefit of porting an exiting game is the assets are already there. I myself don't have time or skills to draw new gfx for another game.

[agermose]

Originally Posted by saimon69

Am not involved with the project but i think that the dual playfield AGA sgould provide a decent coverage of assets from megadrive, with some palette tweaks per area, the car sprite with its own 16 colors plus a good deal of copperlists...

... if the project reach PC Engine port quality will be already good

The Ferrari in the demo is not a sprite, but a BOB.

I have already used 5 HW sprites for road 0, and sprite 7 is gone. That leaves only 2 sprites, which can be only 64 pixels wide, and each only 3 colours.
The Ferrari is 84 pixels wide and has 14 colours.

I might be able to squeeze the image to 64 pixels, and attach 2 sprites for 16 colours, but it's a huge drop in size.
Open for ideas :-)

[saimon69]

Originally Posted by agermose

The Ferrari in the demo is not a sprite, but a BOB.

I have already used 5 HW sprites for road 0, and sprite 7 is gone. That leaves only 2 sprites, which can be only 64 pixels wide, and each only 3 colours.
The Ferrari is 84 pixels wide and has 14 colours.

I might be able to squeeze the image to 64 pixels, and attach 2 sprites for 16 colours, but it's a huge drop in size.
Open for ideas :-)

This makes me wonder: how will you do the road assets and incoming cars?

[agermose]

Originally Posted by saimon69

This makes me wonder: how will you do the road assets and incoming cars?

Roadside objects and traffic will be blitter objects, using a shared colour palette.
It will not be as colourful as the arcade.

To make the game playable, framerate is the most important thing, and the dual playfield setup was chosen for this reason.

[saimon69]

A well thought 16 color palette could make wonders, see the fedepede conversion - plus you will not need to care for road and horizon and that increases slots ^^

[saimon69]

Originally Posted by agermose

The music in the demo is actually 2 channels only!
Uses too much memory though, so some adjustments are needed.

for how it sounds good it seems to me it used chunks instead of partitions so yup i guess it might be on the 300/400k; a mixed approach and three channel should be MAYBE less heavy

[saimon69]

I wonder if the assets from the Megadrive versions could be reduced to 16 color more easily than arcade assets...
Outrun Megadrive Sprites

[kamelito]

Found this probably already known.
https://github.com/djyt/system16_sprite_viewer/releases

[agermose]

Originally Posted by saimon69

I wonder if the assets from the Megadrive versions could be reduced to 16 color more easily than arcade assets...
Outrun Megadrive Sprites

Perhaps, but they are also somewhat different.

[agermose]

Originally Posted by kamelito

Found this probably already known.
https://github.com/djyt/system16_sprite_viewer/releases

Yes we use this tool as well

[dlfrsilver]

Originally Posted by agermose

Yes we use this tool as well

good that's the easiest to get perfect sprites

[Interceptor]

just curious what the remit is for this, make it look as close to the arcade as possible or create the best outrun game the amiga can do and work around the differences?

if you're not fixated on the look, some things can be sacrificed, the speed and rpm does not have to be overlaid on the screen, it could have black bars top and bottom to display these if that saves on sprites etc. i think the C64 version did that.

is sprite size an issue? PC Engine version had smaller sprites and they looked okay, although they only had to change the horizontal size i guess. but if the sprites are re-worked i'm sure they can be scaled down.

i attached an example of the car just to show the size can be brought down and still resemble the original with some touching up.

maybe its just me, but a version of outrun that is remarkably different that the arcade due to machine limitations is more interesting that a poorer clone of something we can play on the same device now anyway.

[gimbal]

Originally Posted by Interceptor

maybe its just me, but a version of outrun that is remarkably different that the arcade due to machine limitations is more interesting that a poorer clone of something we can play on the same device now anyway.

Yeah okay, but then you might as well say that Lotus is it There are plenty of alternatives, the mission that people have is to right the wrongs that history taunts us with. In this case: a really poor port of Outrun (and Turbo Outrun).

... and to flex skills of course

[saimon69]

If fedepede04 will finally be able to finish its tweak of the STe version and someone will port it on Amigawe will have TWO decent ports: one for OCS/ECS and ths one for AGA, but is a win-win!

[agermose]

Originally Posted by Interceptor

just curious what the remit is for this, make it look as close to the arcade as possible or create the best outrun game the amiga can do and work around the differences?

if you're not fixated on the look, some things can be sacrificed, the speed and rpm does not have to be overlaid on the screen, it could have black bars top and bottom to display these if that saves on sprites etc. i think the C64 version did that.

is sprite size an issue? PC Engine version had smaller sprites and they looked okay, although they only had to change the horizontal size i guess. but if the sprites are re-worked i'm sure they can be scaled down.

i attached an example of the car just to show the size can be brought down and still resemble the original with some touching up.

maybe its just me, but a version of outrun that is remarkably different that the arcade due to machine limitations is more interesting that a poorer clone of something we can play on the same device now anyway.

Initially the intention is to use the same sprites sizes as the arcade, because they fit the size of the road. Scaling down sprites is only being looked into if performance is not good enough.

About playing on the same device. On my original A1200 I cannot play cannonball Outrun or whatever is being referred too. I want the game to run on original 90's AGA HW (meaning A1200,A4000,CD32).

Changing the look slightly to increase playability is certainly an option. But sacrificing let's say the second road, like the original Amiga Outrun did, is not.