Crappy C64 screen resolution

[saimo]

Originally Posted by AestheticDebris

It's worth noting that, whilst undoubtedly groundbreaking, the Filmation games aren't exactly nippy on the Spectrum either. The code does a lot of things in a sub-optimal way, so there's a lot of scope for speeding up the Spectrum versions (if anyone saw the need).

If the code is suboptimal, then the C64 transpiled code is subsuboptimal. Don't forget that the code of the C64 versions has NOT been handwritten, but translated from Z80 binary code by means of a tool (and then hand-optimized in some places) - and yet it performs just like the original versions.

There isn't really a C64 isometric title that does quite as well as Head over Heels does on the Spectrum (the C64 version is not bad, but some rooms are simplified for performance reasons).

Here is what emu has got to say about Head Over Heels (and Fairlight):

Yes, I’m sure Fairlight can be improved, in fact I have an unfinished C64 version based on an optimised Atari version siting on a hard drive somewhere. It only has the sprite draw routine improved but it still runs about 30% faster.

Head over Heels has a frame limiter set to 12.5 fps. So it runs at the same speed for all versions including the 16 bit versions. The more complex screens might slow down a bit but I don’t see much difference between the various versions. Adding hardware sprites into the mix does allow more colours to be used of course.

Edit: check out all emu's posts in that thread for even more interesting information.

[tomcat666]

Originally Posted by TCD

There is also an Amiga version of that game: https://amiga.abime.net/games/view/raffles

And also CPC one which is similar to C64 but MUCH more colourfull (definetly better looking ).

[TCD]

Yep, looks a lot nicer than the C64 version: [ Show youtube player ]

[AestheticDebris]

Originally Posted by tomcat666

There is one isometric game on C64 that uses multicolor mode and is very fast - it is a full isometric game with objects you can pickup and everything - Inside Outing, the main character and some of the enemies are sprites so they have individual colours. Very nice.

[ Show youtube player ]

Looks nice, the drawing/wipe effect when you change room isn't swift but it does the same thing on the Spectrum and Amstrad too so it's possibly meant to be a stylistic thing rather than just being slow to draw (like Last Ninja 2).

It's obviously not as colourful as the Amstrad version (or C64 Last Ninja 2 for that matter). I guess that's down to the complexity of arranging the colours because isometric objects don't line up nicely with the colour attributes. Still it shows that using sprites and masking them manually can be efficient.

[saimo]

@TCD

Indeed. From the video, I see that the C64 version uses for the background only 4 colors per room, so I wonder if the multicolor character mode has been used, instead of the bitmap mode, which would have allowed a lot more freedom for color placement (I can't check as I don't have access to a computer now). Anyway, even with the bitmap graphics mode, maybe the Amstrad CPC version couldn't be matched, as its bitmap mode allows complete freedom (the "maybe" is due only to the fact that, at first glance, the Amstrad CPC version keeps the very clean graphics style, without cramming too many differently-colored pixels together).

[tomcat666]

Originally Posted by saimo

Indeed. From the video, I see that the C64 version uses for the background only 4 colors per room, so I wonder if the multicolor character mode has been used.

Yes it has, but still it COULD of have 1 individual colour per each 8x8 block, which they didn't use for some reason and went for same 4 colours on the whole room. It is static screen so this should be of absolutely no performance consequence. Still CPC has an advantage here of using more colours. Nice game too.

[AestheticDebris]

Originally Posted by saimo

Here is what emu has got to say about Head Over Heels (and Fairlight):

Edit: check out all emu's posts in that thread for even more interesting information.

Interesting thread. Head over Heels does run the same speed as the Spectrum/Amstrad versions (as emu says, it's a deliberate rate limit so the speed of movement doesn't constantly jump around). However, a few of the more complex rooms pushed the C64 over that budget and so had to have their designs simplified. I've had a look to see if anyone has ever picked apart the exact differences but there doesn't seem to be anyone, oddly enough.

I do think the C64 version could have been pushed further if the sprites had been used for characters/ enemies. As I said I remember have a long chat with TMR about it back in the day and he reckoned the savings would've been enough to restore those altered rooms (and add a splash of colour). I couldn't persuade him to try and have a go though

Originally Posted by tomcat666

Yes it has, but still it COULD of have 1 individual colour per each 8x8 block, which they didn't use for some reason and went for same 4 colours on the whole room. It is static screen so this should be of absolutely no performance consequence. Still CPC has an advantage here of using more colours. Nice game too.

The problem is that these types of isometric games generally aren't built up out of fixed, square characters. You have the isometric objects stored "as is" and then you place them all to draw the screen. This is particularly important if you need to be able to push blocks around etc.

On the Amstrad, that's easy because all objects can use any of the 16 colours and it doesn't matter how they overlap. On the C64 you have to deal with the fact the pretty much every block is going to be partially overlapping with another one. So either you make them share the same colours, favour the colour of one block over another (creating attribute clash like issues) or somehow try to arrange things such that blocks always overlap with "safe" colour combos (which is difficult to guarantee).

[Megalomaniac]

The C64 has a mode which can match or exceed most of the display features of the Spectrum - the resolution is slightly higher, and the two colours used can be freely chosen, it doesn't have the Flash mode of the Spectrum but that's trivial from a gameplay point of view. For 2D games such as Dizzy and Saboteur, the performance is very similar. C64 Dizzy has a slight visual edge over Spectrum by removing the times where clash causes Diz to be hidden behind an object, and the tree colouring is more subtle and realistic. Saboteur looks nicer on the Spectrum for me.

Isometric arcade adventure matching the Spectrum's potential for resolution, colour and speed are an incredibly rare thing. As mentioned the Filmation games were quite early in the Spectrum's life, I'd say things like HoH, Fairlight and The Great Escape outdo them technically - and the Spectrum wins overall compared to the respective C64 versions. C64 HoH is close but with a few compromises here and there (and who knows if Spec HoH could have run even faster without the precautionary framerate limit?), and C64 Great Escape has a smaller window and agonisingly choppy scrolling. Fairlight is much slower on C64, though a few rooms look better than on the Spectrum, I'd say the C64 red is an advantage when used for background (though its a letdown in many other situations), and the slight visual rejig of the white-background rooms is probably beneficial, but the Spectrum yellow makes for a nicer backdrop colour. And then there's things like Where Time Stood Still or Get Dexter AKA Crafton et Xunk (Amstrad only), where they didn't even try C64 versions.

Still, other games show that the C64 can do it to an extent, within certain conditions. Last Ninja 2 makes great use of low-res for isometric, and Spindizzy feels like impressive isometric hi-res, but those are slightly distinct genre. Inside Outing is hugely impressive on the C64, and does, perhaps uniquely, outdo the Spectrum version - it is slightly faster on the Spectrum, especially the transitions between rooms, but the visual difference does make the C64 version a nicer experience, especially as its got so little direct competition on the C64. I'd say the Amstrad version is the best of all 8-bits for Inside Outing though, the most colourful and as fast as the Spectrum version, even if the varied colour floors on the C64 are nice. How was C64 Inside Outing achieved, and could the tricks be used to make a better C64 Fairlight / HoH etc?

[TCD]

Why not ask those questions on Lemon64?

[AestheticDebris]

Found a comparison video which, somewhat accidentally, shows how the C64 version of Head over Heels is tweaked to keep it running at the same performance level. Note how the number of enemies in the final screen of the Speccy (and Amstrad) version is 3, whereas it's decreased to just 2 on the C64

[ Show youtube player ]

Even more interesting is the fact the Amiga version also only gets 2 robots in the room. Since it was coded by the same guy who did the C64, he presumably just reused the level data he'd created for the C64 version, forgetting that it had been cut down (I very much doubt the Amiga would've struggled with frame rate!)

[roondar]

I do wonder how the 'arcade isometric game' ports did this? Games like Pac-Mania or Zaxxon and others (Zig Zag and Marble Madness sprint to mind) were displayed in an isometric style and run at high frame rates despite that. Do they cheat and not show an actual isometric image (i.e. perhaps they don't occlude sprites properly, or make sure no occlusion is ever needed)?

I did not fully check these kind of games, but I find the performance difference (not just on C64, but in the wider context) very interesting to see.

If this is too off-topic, we can of course discuss it elsewhere!

Edit: I checked out a few of these games now, it does seem they don't occlude Sprites. Level design is usually made so that complex overlapping situations don't exist and the few games that do show Sprites going behind things seem to just use cleverly set Sprite priority settings, rather than more complex methods.

[tomcat666]

There is a HUGE difference in CPU power that you need between the real iso3d games like HoH, Knight Lore, etc. and the "Arcade" isometric view games you mention.

- Full bitmap mode vs Character mode graphics (8 times more to update in Full Bitmap mode which real iso3d games use)
- Usage of sprites - real iso3d mode games in most cases don't use sprites (Inside Outing is one of the exceptions) so they need to do full bitmap drawing every time. Arcade games usually use sprites as much as they can and do the overlapping using sprite to sprite and sprite to background priorities.
- Masking of the objects - for the real iso3d games when any object overlaps with any other object you need to mask them - do a "cookie cut". Also if objects are stationary it is much faster. So the speed goes drastically down when there are more moving objects and even more down when they are overlapping. With the arcade iso3d games this is usually not that complex and can be dealt with priorities.
- All objects in real iso3d games can be freely positioned, so you need to do all the calculations. In the more arcade games usually the Y coordinate is not even considered, they are more like a normal flat scrolling game just with a bit of skew.

In reality the Arcade isometric games are not really that isometric when it comes to implementation, more like standard scrolling games with a bit more complex positioning.