How I make SC2 interlaced graphics manually.

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Por Paulbrk

Hero (611)

Imagen del Paulbrk

01-11-2010, 01:16

Hi,

I like to show you how I make graphics on screen2 interlaced.

The program I use is the Promotion of PC, to make a graph with MSX1 palette and subject to the limitations of color that has Screen2, activating the grid, then I add another frame, at the second frame made the changes, to animate use the key number 2, we see how interlace, although not shown as well as in a real msx but help us, the program is this:

img42.imageshack.us/img42/9431/promotion.png
By tonigalvez at 2010-10-26

Here I can show you how to mix colors by stripes, the color range is increased to have over 100 colors in a MSX1:

img547.imageshack.us/img547/5854/sc2int02.png
By tonigalvez at 2010-10-26

+

img169.imageshack.us/img169/582/sc2int01.png
By tonigalvez at 2010-10-26

Result

img5.imageshack.us/img5/6964/sc2mix.png
By tonigalvez at 2010-10-26

This sunset:
img841.imageshack.us/img841/996/ending2frames.png
By tonigalvez at 2010-10-26

Result

img188.imageshack.us/img188/2981/endindblueversionmixed.png
By tonigalvez at 2010-10-26

A logo:

img827.imageshack.us/img827/2996/logo02r.png
By tonigalvez at 2010-10-26

+

img713.imageshack.us/img713/5206/logo01h.png
By tonigalvez at 2010-10-26

Resulting

img408.imageshack.us/img408/2245/logomix.png
By tonigalvez at 2010-10-26

This is some screens from Menace game we released on MSXDEV 2009:

img688.imageshack.us/img688/2724/intro03.png
By tonigalvez at 2010-10-26

Resulting

img245.imageshack.us/img245/6110/mezcladetodo3x.png
By tonigalvez at 2010-10-25

All using only MSX1 palette, you see using interlaced get 3 colors for each line of 8x1, plus more variety of colors, while the zone change is small, not so much flash as the demo that is out there with graphics intertlaced, because the demo has large flat areas of color change, that makes it much more annoying. We can swap colors between horizontal lines or frames.

Using a set of 256x64, which like the msx has 3 groups, then use only the first in 256x64 128x64 I put two screens, one beside the other, once finished graph must pass by and get the file BMP2MSX SC2, which is what the programmer needs. Only copy to Vram once, all the interlaced effect is changing the name tables of chars. 50 or 60 times between the two frames.

Solores always used similar range, never a white with a dark blue color, because most noticeable flicker.

Here I put the Menace sprites that use interlacing to get more colors, and can even make semitransparent effect (as they used to use a lot in the Sega Megadrive)

img24.imageshack.us/img24/6510/spritesf.png
By tonigalvez at 2010-10-26

As you see on Menace, we use interlaced in all the game parts, this effect consumes some cpu but not too much.

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Por PingPong

Prophet (4093)

Imagen del PingPong

01-11-2010, 10:11

oh, good for any epileptic people ....

Por NYYRIKKI

Enlighted (6016)

Imagen del NYYRIKKI

01-11-2010, 10:38

Nice, but this is not interlaced picture. This method is called color mixing.

With MSX1 VDP it is not possible to make interlaced pictures. With MSX2 you can turn this into interlaced by seting bit 3 on VDP register 9. In BASIC enabling interlace on your program can be done also with "SCREEN,,,,,1" command. To avoid wrong order of odd and even frame I suggest you to sync your program with VDP status register 2 bit 1. (If you really want to make interlaced pictures and not color mixed)

The idea in color mixing is to increase number of colors.
The idea in interlacing is to increase resolution.

Por Paulbrk

Hero (611)

Imagen del Paulbrk

01-11-2010, 10:44

I call interlace because it flicks the same way, but it is color mixing. People called interlace, take a look to this link:

http://www.msxblue.com/?p=2333&lang=en

Ping pong, maibe you do not like it, but is a nice trick for increasing the graphics capabilities of MSX1 VDP, I know some people like it, you can see a lot of c64 and Amstrad CPC demos that use this trick.

Por Paulbrk

Hero (611)

Imagen del Paulbrk

01-11-2010, 10:58

On this page, of c64 graphics expanding capabilities you can see how they try to make a full profit of graphics chip.

http://www.studiostyle.sk/dmagic/gallery/gfxmodes.htm

Take a look, there is a color mixing mode, but they called interlace mode.

Por Hrothgar

Champion (479)

Imagen del Hrothgar

01-11-2010, 11:25

Has anyone ever checked how this looks on an old-fashioned tv set?
I know the complaints of flickering are valid for modern monitors but I'd like to know what it looked like on the original hardware that most people used with their MSXs.

Por Paulbrk

Hero (611)

Imagen del Paulbrk

01-11-2010, 11:55

Its looks fantastic, I have an MSX2+ and a 29" classic TV and the image is awesome.

Por Hrothgar

Champion (479)

Imagen del Hrothgar

01-11-2010, 12:11

If there are really no ugly side-effects on regular TVs I think that
1) emulators should (by default) offer a screen mode that emulates this properly, with no flickering and still readable scroller texts (currently it's either-or)
2) this technique should stop being criticized and used more often.

Por PingPong

Prophet (4093)

Imagen del PingPong

01-11-2010, 12:49

Its looks fantastic, I have an MSX2+ and a 29" classic TV and the image is awesome.
Uhm, on msx2+ you do not need this to achieve good gfx...
Anyway, how does you change the name table every frame?
a) Do you blit from ram every blank or
b) you simply do relocate the nametable address to another vram area of 768 bytes?
(assuming there is some hole in vram to use for an alternate nametable, i've not verified)

I'm curious...

Por Paulbrk

Hero (611)

Imagen del Paulbrk

01-11-2010, 13:36

The coders are Koga, Bifi and Guyver, they will answer you question, I am only a graphic artist.

I think, they relocate name tables on VRAM, we only use the first 256 chars. No memory transfer or blit is made.

Por yzi

Champion (444)

Imagen del yzi

01-11-2010, 14:45

OK, color mixing or interlacing... The purpose is to mix colors, but we called it interlacing. If you watch it on a modern flatscreen monitor, the two color components are indeed interlaced and "mixing" happens only if you look at it from far away enough. But on a proper 1980s CRT video monitor like Philips CM-8833 or an old "tube TV", it looks really good. Here's the link to our screen 2 color mixing demo from last summer:
http://www.pouet.net/prod.php?which=55681

Our mode uses dual nametables (which doesn't use any CPU, if the picture uses only 128 different 8x8 blocks per slice), mixed with CPU "blitting"/uploading to increase the displayed area. Also, if there are similar 8x8 blocks inside the same 1/3 slice, the converter automatically reuses the same character position to save VRAM. In case someone's interested, a viewer application with source code is available here: http://www.kameli.net/lt/prod.htm and some carefully converted sample pictures here: http://ftp.kameli.net/pub/lt2pics

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