what is this XGA

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By PingPong

Prophet (3758)

Аватар пользователя PingPong

26-08-2021, 22:10

Hi,
Is there support for those features.? (combined togheter) :
32 sprites of 16x16 with at least 4 colors (no pixels limits as 9938) on same scanline
256x192 with 16 paletted colors
Omnidir fullscroll
Tiled mode
Fast (how much?) blitter commands
Maybe two layer?

By JunSoft

Resident (42)

Аватар пользователя JunSoft

27-08-2021, 02:16

According to my blog:

hi-resolution mode
512x424 resolution
8 bit per pixel, 256 color palettes
4 pages

​low-resolution mode
256x212 resolution
8 bit per pixel, 256 color palettes
pattern mode support
sprite support

​pattern mode
pattern size: 8x8 or 16x16
pattern map size: 64x64
number of patterns: 256 (max. 8 sets)

​sprite
pattern size: 16x16 or 32x32
number of patterns: 256 (max 4 sets)
number of display planes: 106 (32x32) or 256 (16x16)

ETC
color: 256 palettes, 15-bit RGB
scroll function: Pixel by pixel in X/Y directions

Now more features added, and will be added.
Check my videos and let me know if you have more questions.

By PingPong

Prophet (3758)

Аватар пользователя PingPong

27-08-2021, 12:48

Hi, i've alrady checked your site, but i do not have found an answer to my questions :

JunSoft wrote:

According to my blog:

​pattern mode
pattern size: 8x8 or 16x16
pattern map size: 64x64
number of patterns: 256 (max. 8 sets)

So i see that you cannot cover the entire screen visible area with unique patterns like it does the TMS VDP, guess i ?

Quote:

​sprite
pattern size: 16x16 or 32x32
number of patterns: 256 (max 4 sets)
number of display planes: 106 (32x32) or 256 (16x16)

Those are the number of planes per screen or the number of sprites/scanline? It does make a lot of difference.
You didn't specify if there are color limitations in sprite pixels like the v99x8 nor the number of bits per pixels...

Quote:

ETC
color: 256 palettes, 15-bit RGB
scroll function: Pixel by pixel in X/Y directions

I assume that scroll support is available in all graphic modes, am i wrong?

What about blitter commands? can give some kind of more detailed description?

By JunSoft

Resident (42)

Аватар пользователя JunSoft

27-08-2021, 14:21

pattern layer
256 patterns over a screen are possible. They can't cover the entire screen.
However, in the case of "screen mode 0", there are two pattern layers so 512 patterns are available in total.
In addition, one graphic layer can be used as a background.

sprite layer
maximum 256 sprites over a screen can be shown without scanline limitation.

color
Each (sprite) pattern is a 8-bit pixmap, so you can use 256 colors per pattern.

scroll
You can scroll each layer by pixel. Check my video "6-layer demo".

VDP command
There will be several transfer commands. I can't say more but at least the "copy" command is already implemented.

Most important thing is that the specification is currently not concrete. Smile

By PingPong

Prophet (3758)

Аватар пользователя PingPong

27-08-2021, 15:11

JunSoft wrote:

pattern layer
256 patterns over a screen are possible. They can't cover the entire screen.

this is interesting, maybe can you consider to implement a kind of mechanism where the patterns could be 1024 in a similar way the tms vdp does by deriving the first two most significant bits of a 10 bit pattern number based on the 1/4 vertical area of screen displayed ( i mean 0-63, 64-127, 128-191, 192-255) ?

By JunSoft

Resident (42)

Аватар пользователя JunSoft

28-08-2021, 00:48

PingPong wrote:
JunSoft wrote:

pattern layer
256 patterns over a screen are possible. They can't cover the entire screen.

this is interesting, maybe can you consider to implement a kind of mechanism where the patterns could be 1024 in a similar way the tms vdp does by deriving the first two most significant bits of a 10 bit pattern number based on the 1/4 vertical area of screen displayed ( i mean 0-63, 64-127, 128-191, 192-255) ?

Hmm my posting written in yesterday is disappeared ... (site unstable?)

Any way, that's possible. But if you need "tile-animation", you must write data to VRAM 4 times.
There are pros and cons.

My question is "256 patterns not enough?" (512 patterns in total, covering half screen. Of course you can fill the entire screen with duplicated patterns)

By Juan Luis

Master (135)

Аватар пользователя Juan Luis

28-08-2021, 15:24

JunSoft, how many KBytes of VRAM will XGA support?

By JunSoft

Resident (42)

Аватар пользователя JunSoft

29-08-2021, 01:45

Juan Luis wrote:

JunSoft, how many KBytes of VRAM will XGA support?

How many bytes do you need?Smile
Currently 1MByte RAM installed. I consider 2MB or 4MB in the future, but I'm satisfied enough with 1MB at this moment.

By Juan Luis

Master (135)

Аватар пользователя Juan Luis

30-08-2021, 18:12

The quantity of VRAM is important for a game with large maps like Turrican. More memory means more variety of patterns. MSX does not support DMA memory transfers, so if we are developing under such requirement, the program would have to transfer pattern definitions during game execution by out instructions.

itis interesting a video card with a lot of memory in order to avoid this kind of problems. I consider GFX9000 with 512 KBytes has enough memory for that purpose, and of course, XGA with 1 MByte should satisfy any developer. Smile

JunSoft, thanks for your answer. Please, don't cease of uploading videos with your progress.

Thanks.

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