Impossible Mission - impossible forever? Plus/4 port

[Heaven/TQA]

just run into this:
 

so... no C64 hardware sprites... anybody looked into it and dares to port?

 

[Beeblebrox]

Would be interesting should someone be interested in porting IM to A8, whether the colour scheme and animation could be improved. Don't get me wrong the animation is pretty cool. Just colours are washed out and a bit garish IMHO.

 

I am just thinking what Rensoup and team did with Prince of Persia - where the animation and colour schemes used play to A8 strengths and look amazing. Rather than a basic port they took the BBC code and completely went all out. (Tix's animations are amazing).

 

Maybe the IM character colours could be potentially a little more colourful and the green backgrounds tweaked a little? 

 

Just a thought. I appreciate it would be down to A8 limitations, modes used, sprites, etc etc. (Not technical here as you can see)

 

A reminder:

 

PoP on other 8-bits:

C64 

 

Amstrad:

 

 

PoP on A8:

 

   

 

 

 

[bfollowell]

I always wanted this game on the A8! My buddies with C64s all had it and I was so envious.

 

[xxl]

45 minutes ago, Heaven/TQA said:

anybody looked into it and dares to port?

I think the easiest and fastest way is to take the engine from the Oric version and replace the graphics.

 

 

 

[Wrathchild]

https://atarionline.pl/forum/comments.php?DiscussionID=4746&page=1

[+MrFish]

9 minutes ago, Wrathchild said:

https://atarionline.pl/forum/comments.php?DiscussionID=4746&page=1

Now that's what I call a flattop haircut.  

 

 

Kidding aside, it looks pretty good. I don't think I'd seen it before. Wonder if there's plans to continue? (last post: Gonzo 3/8/2019)

 

[Heaven/TQA]

I would try to get the P4 codebase running… full game, bitmap/charmode… and see how far we can get…

[Rybags]

Likely the Plus4 port uses 256 characters and is likely heavily reliant on colour attributes.

 

For VBXE - almost a walk in the park.  I ended up converting Quadrillion by leaving it rendering bitmap and attributes natively then just using blits to massage that data into linear for Atari and attributes to suit VBXE.

 

For legacy only - I should think a significant rewrite would be in order.  If the source is available then of course it would be a good idea to rework it to utilise PMGs and extra sound capabilities.

 

I might fire up the emu and see what mode it's using.

[Poison]

It is playable 

 

Impossible Mission.atr

Edited January 4, 2023 by Poison

[Heaven/TQA]

 

[Wrathchild]

BBC's aspect-ratio is different IIRC

[Rybags]

That looks like it's using a 160 x 200 mode with 4 colours.  I would guess as a memory saving measure, it can do 16 colours in that mode - though it's only got the 8 colour RGB component possibilities so the other 8 have to be alternating between 2 colours.

From memory the BBC pixels are fairly close in aspect ratio to a PAL Atari.  We had them in the last 2 years of school and most modes fairly filled the monitor (so possibly closer to an NTSC Atari pixel)

 

I just checked the Plus4 version - it is using multicolour text mode.  From what I've seen so far there appears to be no attribute clash so possibly they chose robot colours based on matching the searchable objects that they can overlay.

[zbyti]

 

[Wrathchild]

2 hours ago, Rybags said:

hat looks like it's using a 160 x 200 mode with 4 colours.

 

[Heaven/TQA]

5 hours ago, xxl said:

I think the easiest and fastest way is to take the engine from the Oric version and replace the graphics.

 

 

 

 Well… sad we came not further.

[oky2000]

People assume the TED chip is crap, well the sound is for musical use but SFX are up to VCS/7800 quality, when in reality it's the 16kb minimum spec that ruined that machine. In the right hands it's better than the Amstrad (remember the sound from Amstrad games comes from a little 1.5cm speaker inside the case even when using the RF modulator lol so who cares, it ALWAYS sounded bad).

 

 

 

121 colours, hardware pixel offset screen positioning (sub pixel in the case of multicolor mode horizontal scrolling, fast character based screen modes, fast CPU, ways to get many colours per character on a row of characters etc). Had it gone on sale with 48-64kb at £80/$80 as Jack intended it would have wiped the floor with the low end competition.

 

The great ambient sound/sfx/speech of the game is the best bit about the C64 port. 

[Steril707]

9 hours ago, xxl said:

I think the easiest and fastest way is to take the engine from the Oric version and replace the graphics.

 

 

 

 

This looks a bit better, though...

 

Seems doable to me...

 

add/edit: Concur on the Plus4 being underappreciated. It's a good machine on paper. Just not a good sound chip, and lack of sprites. But the Spectrum and the CPC didn't have either, so who cares.

 

Edited January 4, 2023 by Steril707

[Heaven/TQA]

12 hours ago, xxl said:

I think the easiest and fastest way is to take the engine from the Oric version and replace the graphics.

 

 

 

Is there any fast way to merge those 6bit per byte of sprite etc?

[rensoup]

this one looks interesting:

 

 

While it's always entertaining discussing ports, the amount of work is just humongous (even for a crap game...). For PoP, I had the commented source code, which made it less humongous a task.

 

Without the source, you need to figure out what the code does AND you need to produce a relocatable source so that blocs of data/code can be moved around. The amount of work required for that is likely to burn you out, if not completely at least enough to not make you not want to bother trying on making A8 specific improvements.

 

A good candidate for a port is a good game with commented and buildable source on the original platform... not many of those are available.

 

For producing a relocatable source it may be possible to rely on some custom emulation which would automatically anotate a simple disassembly.  My point is that better tools are required if we want to make those quality C64 ports happen.

 

[Heaven/TQA]

6 hours ago, rensoup said:

this one looks interesting:

 

 

While it's always entertaining discussing ports, the amount of work is just humongous (even for a crap game...). For PoP, I had the commented source code, which made it less humongous a task.

 

Without the source, you need to figure out what the code does AND you need to produce a relocatable source so that blocs of data/code can be moved around. The amount of work required for that is likely to burn you out, if not completely at least enough to not make you not want to bother trying on making A8 specific improvements.

 

A good candidate for a port is a good game with commented and buildable source on the original platform... not many of those are available.

 

For producing a relocatable source it may be possible to rely on some custom emulation which would automatically anotate a simple disassembly.  My point is that better tools are required if we want to make those quality C64 ports happen.

 

Well… that was my intention in the P4 new port… regarding available experience and source.

 

those Oric and BBC ports help maybe to get things done as those machines have less RAM and simpler architecture as for Oric the highres bitmap is at a000-bfff e.g. 

[+MrFish]

20 hours ago, rensoup said:

While it's always entertaining discussing ports, the amount of work is just humongous (even for a crap game...). For PoP, I had the commented source code, which made it less humongous a task.

 

Without the source, you need to figure out what the code does AND you need to produce a relocatable source so that blocs of data/code can be moved around. The amount of work required for that is likely to burn you out, if not completely at least enough to not make you not want to bother trying on making A8 specific improvements.

@mrsid finished his Prince of Persia port right before the source code was released. Quite the learning experience on his part.

 

One of the authors of the C64 -> 7800 conversion of Impossible Mission showed up some years back. He was able to resurrect the source, but wasn't willing to share it, unfortunately.

Impossible Mission: Successful recompile of source code 

Impossible Mission - guess who ?

 

[rensoup]

15 hours ago, Heaven/TQA said:

Well… that was my intention in the P4 new port… regarding available experience and source.

 

those Oric and BBC ports help maybe to get things done as those machines have less RAM and simpler architecture as for Oric the highres bitmap is at a000-bfff e.g. 

Assuming the P4 author is willing to pass it, then yeah it'd be a better start than the Oric or BBC without source. Pretty unbelievable that it's available on Oric too 

 

Also never noticed that the main sprite on C64 is hires until now.

 

14 hours ago, MrFish said:

@mrsid finished his Prince of Persia port right before the source code was released. Quite the learning experience on his part.

A multi year one indeed...  and so much effort was spent on rebuilding the source which like you said was recovered right after! But I won't argue why people like to do certain things which seem pointless to others.

 

14 hours ago, MrFish said:

One of the authors of the C64 -> 7800 conversion of Impossible Mission showed up some years back. He was able to resurrect the source, but wasn't willing to share it, unfortunately.

Interesting read! Too bad the author seems to lack the motivation... Perhaps it's time to ping him again.

[Rybags]

Each one has it's pros and cons.

 

As a porting project maybe the BBC would be easiest but has the problem of 256 pixel height.

From a quick play of the Plus4 version the gameplay is very close to the C64 original which IMO has the best gameplay of any version, Amiga included.

 

IMO the biggest technical hurdle for a C64 or Plus4 port isn't the lack of sprites or lesser attribute cell capability, it's the fact we have 128 instead of 256 usable text characters.

 

If I was to do a VBXE assisted port I'd use the C64 version.  Without source code the required effort would be much the same as for any other 6502 version (though BBC probably easier) but would give the best end product.

[Heaven/TQA]

6 hours ago, Rybags said:

Each one has it's pros and cons.

 

As a porting project maybe the BBC would be easiest but has the problem of 256 pixel height.

From a quick play of the Plus4 version the gameplay is very close to the C64 original which IMO has the best gameplay of any version, Amiga included.

 

IMO the biggest technical hurdle for a C64 or Plus4 port isn't the lack of sprites or lesser attribute cell capability, it's the fact we have 128 instead of 256 usable text characters.

 

If I was to do a VBXE assisted port I'd use the C64 version.  Without source code the required effort would be much the same as for any other 6502 version (though BBC probably easier) but would give the best end product.

Does the p4 use char mode or bitmap mode? If bitmap mode there are no limit for chars?

[Rybags]

FF06:  1B

Test mode off, bitmap off, blank screen off, 25 rows, VSCROLL = 3

 

FF07:  98

HW reverse chars off (256 chars), multicolour mode on, 40 cols, HSCROLL = 0

 

 

For this game it wouldn't make a huge amount of sense to use bitmap mode given lack of complexity of the rooms.  Rendering the sprites would take slightly more time but the restore operation would be much quicker.