Graphics 7 for imaging?

[emkay]

Has anyone ever thought of a gr. 7 fullscreen DLI mode?

 

What would be the benefits, you ask?

 

1. no flicker

2. no "dirty-line"

3. every second screen-line is free from DMA without any SW-tricks

4. enough time to multiplex the 2 players

5. enough time to switch colour registers every "half" Gr.7 line

6. combined colour resolution for more than 24 colours every 2 lines

7. easiest logic for importing PC graphics while using non-interlaced modes.

 

 

The difference to G2f is that such a screen really always needs the full CPU-power for a fullscreen DLI. And a movement of screenparts will be nearly impossible while you can simply move the charblocks in charmode.

[analmux]

{ My exams are over: time to code , but.....}

 

@ emkay

 

Well, I don't know.....

 

when we have no 5th color we want to use GED I suppose, but there would be a timing difficulty. On every second line we have extra cycles (about 40). They cannot be bridged that easily, see this scheme

 

80 cycles = 40 bytes wide = 160 gr.7 pixels

* = DMA cycle

- = free cpu cycle



first rasterline: 40 graphics DMA fetch cycles + 9 refresh cycles (+additional PMG + DLIST DMA in invisble part):



***-***-***-***-***-***-***-***-***-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-



second rasterline: 9 refresh cycles only



-*---*---*---*---*---*---*---*---*----------------------------------------------

 

As you want to make GED colorcells at the same distance every line, the regchange timing should be the same too on both lines.

 

suppose we have a piece of code in the first line:

 

lda #10      =2 cycles   A

ldx #20      =2 cycles   B

ldy #30      =2 cycles   C

sta colpf0   =4 cycles   D

stx colpf1   =4 cycles   E

sty colpf2   =4 cycles   F

 

NOTE: a store (acc,x,y) instruction only has effect on the 4th cycle

 

then, on the 1st line, it would be like this:

***A***A***B***B***C***C***D***D***D*D*E*E*E*E*F*F*F*F*-*-*-*-*-*-*-*-*-*-*-*-*-

 

on the second line we'd have: {{edited}}

-*---*---*---*---*---*---*AAB*BCC*DDDDxxxxEEEExxxxFFFF--------------------------

 

while on the second line, in order to have the same colored cells, we'd have to fill the *'s with dummy commands (NOPS e.a., to be filled in at x's) which is:

(1) time consuming

(2) not always possible.

 

Conclusion: stick with graphics 15

 

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mux

[Dracon]

In my opinion, gfx#7 mode isn't quite a good selection...

There are just too big pixels there. Even if it is cool when converting graphix from PC (square pixels) I don't like the resolution....

 

BTW. I've heard that the newest version of PHOTOSHOP (CS) has an option to work with non-square pixeled images. So would it be easier for anybody to e.g. paint a 4-color graphix in PS with such feature and then convert it to Atari XE ? I mean this should guarantee that I see similar image on Atari (no more squeezed pictures after conversion) ???

[emkay]

@Analmux

 

Always multiplexing PM would be the first thing... you will run very fast out of cycles then;) but PM-multiplexing ins't that timing intensive

You would need to double Player 1 and 2 for full width Overlay. By this you gain 8 colours at minimum for fullscreen while MCS/G2F is able to use 6 colors at minimum.

 

 

 

@Dracon

 

TIP & HIP are still using a similar resolution plus flicker.

[analmux]

emkay,

 

indeed pm muxing is not the problem, as with GED we can even mux them horizontally, but the GED colorcell handling is VERY critical in timing. And don't forget that horizontal PM muxing is just a waste of time. I've explained a few times before. It should be used as an emergency solution.

 

-----

mux

[emkay]

emkay,

 

indeed pm muxing is not the problem, as with GED we can even mux them horizontally, but the GED colorcell handling is VERY critical in timing. And don't forget that horizontal PM muxing is just a waste of time. I've explained a few times before. It should be used as an emergency solution.

 

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mux

 

Yeah... Let's waste the full CPU Time if necessary

In the DMA-less line you can prepare registers for the DMA line too...

 

Gr.7 + Fullscreen DLI is just one possibility Especially when looking at HIP/TIP-like Pictures without flickering and without black lines ...

[noteit]

You can have two graphic 7 screens on an atari at the same time without flicker. Do this by having a display list that first displays 1 graphic 7 screen, and then continue it with another list. at end of display list have it jump back to first list both lists have seperate screen memory commands, either every line of display list, or at start of each list. (It depends on what you want to do with it.)

.

 

You do have to set the screen pointer or text pointer to point at the screen you want before you use either plot or drawto or print at commands.

 

Think it was locations 88, and 89 that controled the text pointer?

 

Anyway, it does a real nice screen, no flicker on my tv set, and the colors on one screen will mix with colors on other screen to produce new colors.

 

 

Whats neat, you can draw something on one screen, then set the pointers so commands only effect the other screen. Then screen erase etc, do not remove that one sceeen, so its always displayed.

 

A two screen display I think is worth while in gr 7 and recommend you give it a try.

 

Three screen at a time is possible, but flickers a bit and is kind of anoying.

 

I suppose it also depends on if you use a monitor, a tv, and what kind of scan the tv has, and also screen size.

 

I had a small 12 inch color tv when I tried two and three screens at a time.

Used a atari 800.

[miker]

when we have no 5th color we want to use GED I suppose, but there would be a timing difficulty. On every second line we have extra cycles (about 40). They cannot be bridged that easily, see this scheme

 

Wait, wait! - Graphics 7 size pixels are also represented in gr. 13 mode - WITH 5-th color!

 

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Well - there were some games using gr.7 mode - like Draconus, Zybex or Blinky's Scary School - very crappy, eh?

 

I remember also the title screens in Mackintosh/Munns games - also in gr.7 (Crumbles Crisis, Space Lobsters, Black Lamp and so on).

 

I think that with proper use of colors we can make something interesting with this mode (and probably more usable than g2f static pics).

[analmux]

Wait, wait! - Graphics 7 size pixels are also represented in gr. 13 mode - WITH 5-th color!

 

Yes, I know that: just Antic 5 (like I described in the Softsynth2 thread). But we chose gr.7 to avoid badlines to make GED possible on the whole screen.

 

I think that with proper use of colors we can make something interesting with this mode (and probably more usable than g2f static pics).

 

What do you mean? In the Antic 4 MCS mode we can have dynamic pictures too. Just look at the scrolling MCS demo. We don't have to decrease resolution for that (from antic4 to antic5). Though the scrolling MCS demo leaves free cpu time when screen is being drawed (NO fullscreen DLI kernel like in G2F).

 

The main solution for more interesting graphics (that is: for (action-)gaming purposes) is (I think) dividing the screen in regular graphics bands (like rows of 2 or 3 antic 4 lines), and restrict regchanges only to first scanline of the Antic 4 line. That should leave enough cpu-time for calculations.

[Tezz]

Dracon. BTW. I've heard that the newest version of PHOTOSHOP (CS) has an option to work with non-square pixeled images. So would it be easier for anybody to e.g. paint a 4-color graphix in PS with such feature and then convert it to Atari XE ?

Indeed, yes this is true, I have used the new pixel aspect ratio in CS it is very useful when drawing. Remember though that if you want to import into G2F for instance, you must squash the picture to 1:1 horizontally before saving. With this aspect ratio setting, you are realy drawing with 1:1 pixels and displaying 2:1 pixel aspect ratio. So this is already taken care of.

 

BTW. Graphics 7 mode is way to chunky to be of much use, We already had DLI enabled art packages such as Graphics Art Department back in the day anyway. You can produce some reasonable graphics with skilled drawing in this mode but nevertheless it sux. Zybex was probably the only thing I liked in this mode but the C64 version regardless of the usual extra colours used, looked much better.

 

Graphics 12/15 is a million times more useful resolution. Only for special uses where timing is an issue should graphics 7 be used I think.

[emkay]

 

Graphics 12/15 is a million times more useful resolution. Only for special uses where timing is an issue should graphics 7 be used I think.

 

It's a question of usage. Sheddy's Space Harrier is a fullscreen 3D engine that takes usage of Gr.7, which means half Memory usage and 50 percent more CPU speed compared to GR. 15. So you have the double in graphics speed.

 

By using hires or 4 color mode(Gr.15), you need the ability of block moving for compensating the higher CPU usage.

It does make more sense to reduce resolution when trying fullscreen effects and to use Hires if small graphics-ranges are to change.

 

...

[tebe]

emkay, it's only dream

 

4. enough time to multiplex the 2 players  

 

for 4 colors players ?

but this colors is a logical operation on 2 register

 

0 1 0 1

0 0 1 1

 

C64 can set four different colors of sprite

 

 

5. enough time to switch colour registers every "half" Gr.7 line  

 

only for colors bars

 

 

6. combined colour resolution for more than 24 colours every 2 lines  

 

it's imposible in 7gr mode

 

1-st  line    0 1 2 3 0 1 2 3 0 1 2 3 0 1 2 3

2-nd line     0 0 0 0 1 1 1 1 2 2 2 2 3 3 3 3

 

see attached files

gfxc64.zip

[Tezz]

Emkay wrote..It's a question of usage. Sheddy's Space Harrier is a fullscreen 3D engine that takes usage of Gr.7, which means half Memory usage and 50 percent more CPU speed compared to GR. 15. So you have the double in graphics speed.

Yes, of course Graphics 15 requires double the CPU time and in 3D based engines such as Space Harrier, it would no doubt not be feasable to do in graphics 15 on the A8 especially with all the other factors involved with such a feat like the samples and music etc. It's a lot for the 6502 to do even with clever coding.

 

Basically what I meant in my point is that Graphics 7 is very ugly. I understand your point that it is nessasary to use this mode to achive realistic results such as the 3D routines. I think that most A8 users would not like to see anymore blocky graphics in other types of games where it isn't nessasary. Many users were disapointed with Draconus in this mode for instance.

 

It does make more sense to reduce resolution when trying fullscreen effects and to use Hires if small graphics-ranges are to change.

Absolutely