Good explanation why half-brite is too slow for game engines?

[paraj]

Originally Posted by TCD

Yes, I meant EHB I don't have time to play the game right now, but maybe somebody else could provide said files?

Just gave it a quick spin. Loading screens and menus seem to be 5bpls, but ingame is indeed EHB. (Zoned USS file if anybody wants to second guess me )

[TCD]

Interesting. I only checked the color count of some of the in-game screenshots we have on HOL and they have less than 32 colors.

[Amigajay]

Originally Posted by TCD

Interesting. I only checked the color count of some of the in-game screenshots we have on HOL and they have less than 32 colors.

Are we talking Desert Strike here? If so in the manual states they used EHB mode to bring shadows, smoke and shading.

So i guess if colour count a screenshot with an explosion or smoke over something more than just the desert.

Btw the manual states the cut scenes were drawn in 32 colours.

[TCD]

Originally Posted by Amigajay

So i guess if colour count a screenshot with an explosion or smoke over something more than just the desert.

That's what I tried. As an example:


That screenshot uses 31 unique colors.

I didn't analyze every screen the game produces, so there might be some that have more than 32 colors.

[Aardvark]

Originally Posted by TCD

Interesting. I only checked the color count of some of the in-game screenshots we have on HOL and they have less than 32 colors.

The shadow of the helicopter is EHB effect.
In WinUAE, the "No-EHB Denise" option under Adv. Chipset can be toggled on/off while emulation is running.

Without EHB, there is only about 21 on-screen colors.

[TCD]

Okay, that is interesting So EHB is used, but not for the full 64 colors. Would be great if somebody could explain why it is used.

[Dunny]

Originally Posted by TCD

Okay, that is interesting So EHB is used, but not for the full 64 colors. Would be great if somebody could explain why it is used.

I'm guessing so that the shadow could be transparent over any colour.

[Amigajay]

Originally Posted by Dunny

I'm guessing so that the shadow could be transparent over any colour.

Exactly, even if there is only 21 colours, shadow of the helicopter/smoke will need to double that to 42, plus any additional colours for the big screen flash explosion.

As i say above, the manual says why they used EHB mode. I’m sure the tradeoff of a couple of fps was worth it for the extra colours, i know coming from the Mega Drive version, the intro, menu and explosions along with much better sound makes for an all round better game, even if it is slightly slower, not so much of a problem compared to John Madden or Road Rash (still playable of course!).

[TCD]

The manual is clearly written by a person from the marketing department. I meant an explanation why they *didn't* use 64 colors, but only used 32 while EHB is used would be interesting.

[Dunny]

Originally Posted by TCD

The manual is clearly written by a person from the marketing department. I meant an explanation why they *didn't* use 64 colors, but only used 32 while EHB is used would be interesting.

It was for the shadows, I thought. If you use more than 32 colours then you end up the shadow not being effective on some of your colours.

[Karlos]

It's interesting that the helicopter shadow is bitplane 6 but so much else seems to rely on a either with black.

[lionagony]

I came across this interesting message from Bob Pariseau from 1985 in Google Groups about EHB. It has a sample program by Dale Luck, has anyone ever compiled it, would be interesting to see? https://groups.google.com/g/net.micr...m/5qnZJg7ts5cJ

[AestheticDebris]

Originally Posted by TCD

The manual is clearly written by a person from the marketing department. I meant an explanation why they *didn't* use 64 colors, but only used 32 while EHB is used would be interesting.

The hardware can't do 64 selectable colours. You select 32 of them and EHB adds an extra 32.that are the half bright versions. So you're always going to be a bit limited in what the results are.

[TCD]

Originally Posted by AestheticDebris

The hardware can't do 64 selectable colours. You select 32 of them and EHB adds an extra 32.that are the half bright versions. So you're always going to be a bit limited in what the results are.

So the result should be 64 different (not selectable) colors. The screenshots I've looked at have 32 different colors max.

[paraj]

Originally Posted by TCD

So the result should be 64 different (not selectable) colors. The screenshots I've looked at have 32 different colors max.

Yes, but are they the same 32 colors for all of the screenshots? Probably not.

All of the in-game assets (tiles/sprites/etc.) are likely using the same 32 color palette, and maybe you won't actually see >32 distinct colors at the same time, but that doesn't mean the game didn't benefit from EHB. This way they could just designate BPL6 the shadow bitplane, and it would always work regardless of what the artists were doing and would never need to perform complex ingame color swapping.


Here's the palette from the save state I uploaded yesterday:



Maybe if you're at the transition from ocean to desert and certain enemies appear you'll see "actual" benefit, but even if not, I can certainly see why you'd use it from a development standpoint.

[TCD]

So to see more than 32 colors in a screenshot, both ocean and desert need to be visible and some smoke and explosions might do that. I'll get my best agent on that tomorrow

Edit: I just wanted to know why it was done and that explanation makes a lot of sense, so thank you

[paraj]

Originally Posted by TCD

So to see more than 32 colors in a screenshot, both ocean and desert need to be visible and some smoke and explosions might do that. I'll get my best agent on that tomorrow

Edit: I just wanted to know why it was done and that explanation makes a lot of sense, so thank you

I understand what you're looking for, and it would be great for a better "show off" screenshot. Can't promise that desert/ocean transition will deliver, but you want a situation that uses as many of the base colors as possible.

[TCD]

Originally Posted by paraj

Can't promise that desert/ocean transition will deliver, but you want a situation that uses as many of the base colors as possible.

Roger that

[AestheticDebris]

It's also entirely plausible that a developer thought "that would be a cool use of the feature" and so implemented it, even though in the end, once all the assets were created, it turned out to be mostly pointless.

[Dunny]

Originally Posted by AestheticDebris

It's also entirely plausible that a developer thought "that would be a cool use of the feature" and so implemented it, even though in the end, once all the assets were created, it turned out to be mostly pointless.

That would be my take on it.

"Hey we can add shadows for free with EHB"
"What kind of performance hit is that extra bitplane?"
"Negligible"
"Might as well then "

kind of deal.