Graphics 0 text enlarger/reducer.

[ac.tomo]

Can anyone name a couple of demo's for me that increase and decrease the size of Graphics 0 text, it's one of the programs that I intend to put in my book, but thinking off the top of my head there are a couple of ways of doing it, I just want to see the popular way most coders do it. Thanks.

Edited February 24 by ac.tomo

[Rybags]

The MemoPad 480i (Real Interlace Demo) in my tagline does this, vertically.

The general technique is to use VScrol tricks to make the characters taller or shorter.

The hardware also supports the descender mode where you can provide a character set with lower case descenders e.g. for letters g, j etc.

 

To do things such as 64 or 80 character width, it's generally done in bitmap and the characters have to be rendered.

Edited February 25 by Rybags

[+David_P]

6 hours ago, ac.tomo said:

Can anyone name a couple of demo's for me that increase and decrease the size of Graphics 0 text, it's one of the programs that I intend to put in my book, but thinking off the top of my head there are a couple of ways of doing it, I just want to see the popular way most coders do it. Thanks.

Display as bitmaps in Graphics 8, then play with the DL to switch to Graphics 4 or Graphics 6

[Rybags]

There's also software (games and demos mostly) that use a 2x2 matrix of Gr. 0 characters for larger text (16x16 pixels)

 

In theory it would be reasonably simple to do other sizes, e.g. use part of an extra character to increase vertical size by a few pixels.

You could also utilize the entire 8 pixel height and put single blank lines between the Gr. 0 ones to provide seperation.

[ac.tomo]

Thanks for that but I'm actually after enlarging gr.0 text horizontally as well as vertically in bitmap gr.8. I've seen it done scrolling but can't remember the names of the demo's I've seen it in. I could do it but would like to see the demo's, again, to see the popular method. I know it's all bit shifting like rybags mentioned in 16x16 bit blocks.

[Rybags]

Not really bit shifting.

Custom font would be what's needed.  If you're rendering in Gr. 8 then it becomes a bit like softsprites, though you probably don't need to worry about save/restore of background data.

I seem to remember there being an ABBUC software comp entry for this sort of thing a few years ago.  Possibly try the threads for that.

Edited February 25 by Rybags

[pirx]

On 2/25/2024 at 7:12 AM, ac.tomo said:

Thanks for that but I'm actually after enlarging gr.0 text horizontally as well as vertically in bitmap gr.8. I've seen it done scrolling but can't remember the names of the demo's I've seen it in. I could do it but would like to see the demo's, again, to see the popular method. I know it's all bit shifting like rybags mentioned in 16x16 bit blocks.

i think such an effect was in my demo "Equation of Time". SO the technique is rather simple - for horizontal scaling in a scroller what you do is each frame you get a 1-bit wide vector from a character set and ROL A the whole scroll area. So if you repeat the same bit vector several times, you get wider characters on screen. If you skip some vectors, you get narrower characters.
For horizontal scaling of bitmap mode, the most cost-effective are display list modifications - you can repeat a given line or skip it - this effect is also present in the same demo in the upper "barrel", it is much more prominent in "Five2Five" demo (the "carpet" effect).

[+Stephen]

2 hours ago, pirx said:

i think such an effect was in my demo "Equation of Time". SO the technique is rather simple - for horizontal scaling in a scroller what you do is each frame you get a 1-bit wide vector from a character set and ROL A the whole scroll area. So if you repeat the same bit vector several times, you get wider characters on screen. If you skip some vectors, you get narrower characters.
For horizontal scaling of bitmap mode, the most cost-effective are display list modifications - you can repeat a given line or skip it - this effect is also present in the same demo in the upper "barrel", it is much more prominent in "Five2Five" demo (the "carpet" effect).

Wow - I somehow had missed this demo!  Super cool effects.  I'm not understanding your explanation of the horizontal scroller - but I'll keep reading it.

[pirx]

00000000
00111100
01100110
01100110
01111110
01100110
01100110
00000000

this is rather simple, I wanted to be concise, but the gist is that when it is time to display a new letter, say "A" as in the example above, you get a column of 8 bits from the character set, so first you'd get
0

0

0

0

0

0

0

0

then
0

0

1

1

1

1

1

0

and so on,
and place it on the right end of the screen to be ROLled in in the next frame.

[+Stephen]

1 hour ago, pirx said:

00000000
00111100
01100110
01100110
01111110
01100110
01100110
00000000

this is rather simple, I wanted to be concise, but the gist is that when it is time to display a new letter, say "A" as in the example above, you get a column of 8 bits from the character set, so first you'd get
0

0

0

0

0

0

0

0

then
0

0

1

1

1

1

1

0

and so on,
and place it on the right end of the screen to be ROLled in in the next frame.

Thanks - that makes sense, and for scale factor of 3, you would load a column, ROL it in 3 times, then load the next and repeat.

[pirx]

exactly!