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Re: Saving animated sprites from a simple BASIC graphic program

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In article <mpro.q7fjw401gp24s01ps.news@stevefryatt.org.uk>, Steve
Fryatt <news@stevefryatt.org.uk> wrote:
> On 19 Mar, Steve Fryatt wrote in message
>     <mpro.q7ez2g027ab040401.news@stevefryatt.org.uk>:

> > On 18 Mar, Richard Ashbery wrote in message
> >     <5853462123basura@invalid.addr.uk>: 

> > > be a problem with the way the program collects the sprite data?
> > 
> > As Druck says, VDU23,27,1,n| is ugly, and quite dated. I wouldn't
> > be completely surprised if it doesn't take the ORIGIN setting
> > into account, but I can't see any reference to that foible in the
> > manual.

> You're grabbing a screenshot from (-330,-330) to (330,330) relative
> to the current origin (0,0), but at the same time, you're moving
> that origin around to shift the centre of your square. But, of
> course, this /also/ moves the centre of the (-330,-330) to
> (330,330) screen grab, so the grabbed area will /always/ be
> perfectly centred on the square that you've just plotted.

Ah! yes obvious when I think about it.

> I still don't like VDU23,27,1,n| though...

Although this method of creating a sprite group is probably
poor/deprecated it's easy to understand.

I need to get my head round the alternative (OS_SpriteOp). Although
I've been told its easy the last time I looked I didn't find it plain
sailing - I need a good tutorial - I'll do a web search and see what
turns up.

> > However, using ORIGIN seems unnecessary anyway. Why not just plot
> > at the required coordinates, and bypass all of the problems?

> By not moving the (0,0) point around, but instead plotting the
> square at the desired coordinates relative to a single, fixed
> origin, the square will, of course, move within the static
> (-330,-330) to (330,330) rectangle as intended.

Excellent explanation - thanks :-)

Of course your program changes work superbly. Again thanks.

> I would suggest treating ORIGIN as a command to call once, after
> MODE. After that, always calculate the exact coordinates that you
> need for each stage of the graphic. This is no harder than moving
> the origin, as you can see from my code, and completely avoids this
> kind of confusion.

Yes, I see that now and is vastly better.

Richard

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Thread

Saving animated sprites from a simple BASIC graphic program Richard Ashbery <basura@invalid.addr.uk> - 2020-03-17 16:57 +0000
  Re: Saving animated sprites from a simple BASIC graphic program "John Williams (News)" <UCEbin@tiscali.co.uk> - 2020-03-17 17:28 +0000
    Re: Saving animated sprites from a simple BASIC graphic program Richard Ashbery <basura@invalid.addr.uk> - 2020-03-17 20:30 +0000
      Re: Saving animated sprites from a simple BASIC graphic program "John Williams (News)" <UCEbin@tiscali.co.uk> - 2020-03-17 21:12 +0000
        Re: Saving animated sprites from a simple BASIC graphic program Richard Ashbery <basura@invalid.addr.uk> - 2020-03-17 21:23 +0000
      Re: Saving animated sprites from a simple BASIC graphic program News <chrisjohnson@spamcop.net> - 2020-03-17 23:39 +0000
  Re: Saving animated sprites from a simple BASIC graphic program Steve Fryatt <news@stevefryatt.org.uk> - 2020-03-17 22:44 +0000
    Re: Saving animated sprites from a simple BASIC graphic program Richard Ashbery <basura@invalid.addr.uk> - 2020-03-18 17:44 +0000
      Re: Saving animated sprites from a simple BASIC graphic program druck <news@druck.org.uk> - 2020-03-18 20:55 +0000
      Re: Saving animated sprites from a simple BASIC graphic program Steve Fryatt <news@stevefryatt.org.uk> - 2020-03-19 00:08 +0000
        Re: Saving animated sprites from a simple BASIC graphic program Steve Fryatt <news@stevefryatt.org.uk> - 2020-03-19 07:38 +0000
          Re: Saving animated sprites from a simple BASIC graphic program News <chrisjohnson@spamcop.net> - 2020-03-19 10:17 +0000
          Re: Saving animated sprites from a simple BASIC graphic program Richard Ashbery <basura@invalid.addr.uk> - 2020-03-19 20:05 +0000
            Re: Saving animated sprites from a simple BASIC graphic program Steve Fryatt <news@stevefryatt.org.uk> - 2020-03-19 21:10 +0000
              Re: Saving animated sprites from a simple BASIC graphic program Richard Ashbery <basura@invalid.addr.uk> - 2020-03-19 21:59 +0000
      Re: Saving animated sprites from a simple BASIC graphic program Matthew Phillips <spam2011m@yahoo.co.uk> - 2020-03-19 08:23 +0000
        Re: Saving animated sprites from a simple BASIC graphic program Richard Ashbery <basura@invalid.addr.uk> - 2020-03-19 13:34 +0000
          Re: Saving animated sprites from a simple BASIC graphic program Matthew Phillips <spam2011m@yahoo.co.uk> - 2020-03-19 21:10 +0000
            Re: Saving animated sprites from a simple BASIC graphic program Richard Ashbery <basura@invalid.addr.uk> - 2020-03-19 21:40 +0000
  Re: Saving animated sprites from a simple BASIC graphic program "Derek.Moody" <derek.moody@casterbridge.net> - 2020-03-17 18:05 +0000

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