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Groups > comp.sys.acorn.programmer > #6268

Re: White background colour in GCOL is grey.

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In article <ddab484d-c345-461c-aba3-6079f58efa5an@googlegroups.com>,
   George Pearce <chasgpearce@gmail.com> wrote:
> On Thursday, 13 May 2021 at 12:35:21 UTC+1, Martin wrote:
> > In article <bf20a335-0a73-4649...@googlegroups.com>,
> > George Pearce <chasg...@gmail.com> wrote: 
> > > On Wednesday, 12 May 2021 at 18:35:03 UTC+1, Steve Fryatt wrote: 
> > > > On 12 May, Richard Ashbery wrote in message 
> > > > <592b7c18...@invalid.addr.uk>: 
> > > > > In article <912abee8-d3e2-482b...@googlegroups.com>, 
> > > > > George Pearce <chasg...@gmail.com> wrote: 
> > > > 
> > > > > > I am simply trying to open a graphics window with a white
> > > > > > background in 16 million colour mode in RIScOS 4.?. I am
> > > > > > calling MODE MODE in 1900x1080p. GCOL seems to have been
> > > > > > extended in v5. 
> > > > > 
> > > > > > Best I can do is GCOL 0, 191, which seem to give a light
> > > > > > grey rather than full white. I can obviously correct
> > > > > > this after the event, but am sure there must be a
> > > > > > solution which I have yet to discover. 

[Snip]

> > You do not say what version of RISC OS you are using, or which
> > version of BASIC, or what hardware you are running on. Any of
> > those may be your problem - the BASIC manual has been updated,
> > but largely to reflect changes made in the many years since RO4. 
> > 
> > If the problem is the version of BASIC, then the most recent
> > version can be soft-loaded, as Steve said above. 

> I did say at the start of my original question it is RISC OS 4.?,
> as Steve picked up.
Indeed ... which is why I referred to changes since RO4.

> 4.02 on one machine and 4.39 Virtual Acorn RISC OS ADJUST
> BASIC is BASIC 5 v 1.20 on the former and v1.29 on the latter. I
> realise that there may be an issue with emulation, and the lack of
> physical Acorn hardware.
OK thanks.

> I have the BBC BASIC V manual, and it has nothing to say about 16
> million colors but is concerned mainly with 16 and 256 colour
> modes, and old style low res screen modes.
Yes - I find that very confusing myself.

> Also I'm writing the program for someone who is using RISC OS 4,
> and would probably demur from soft loading a new OS!
We are not suggesting softloading a new OS ... just the BASIC module.

> That being said, 5 or 4, no one has addressed my query about the
> existence or not of Foreground and Background colours in 16M mode.
> I suspect not!

> And no one has offered a solution to a white screen in said mode.
> Please someone!

I wrote a little program...
    MODE MODE
    GCOL &8F                :REM Yellow background
    VDU 24,200;200;1000;900;
    CLG
    GCOL &FF                :REM White background
    VDU 24,300;300;1080;800;
    CLG
    PRINT "done"
and when running at X1920 Y1080 C16M I get a yellow rectangle on a
black screen, mostly covered by a white rectangle - which seems to be
what you want?

That is the same on...
    Titanium with RO5.29 and BASIC v1.81
    VRPC with RO4.39 and BASIC v1.80 (softloaded)
    VRPC with RO4.39 and BASIC v1.29

Does that answer your question?
If not, then a misbehaving program might help.

-- 
Martin Avison 
Note that unfortunately this email address will become invalid
without notice if (when) any spam is received. 

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Thread

White background colour in GCOL is grey. George Pearce <chasgpearce@gmail.com> - 2021-05-11 07:03 -0700
  Re: White background colour in GCOL is grey. Richard Coleman <coleman@orpheusmail.co.uk> - 2021-05-12 06:44 -0700
  Re: White background colour in GCOL is grey. Richard Ashbery <basura@invalid.addr.uk> - 2021-05-12 14:53 +0100
    Re: White background colour in GCOL is grey. Steve Fryatt <news@stevefryatt.org.uk> - 2021-05-12 18:23 +0100
      Re: White background colour in GCOL is grey. George Pearce <chasgpearce@gmail.com> - 2021-05-13 02:38 -0700
        Re: White background colour in GCOL is grey. Martin <News03@avisoft.f9.co.uk> - 2021-05-13 12:33 +0100
          Re: White background colour in GCOL is grey. George Pearce <chasgpearce@gmail.com> - 2021-05-13 06:40 -0700
            Re: White background colour in GCOL is grey. News <chrisjohnson@spamcop.net> - 2021-05-13 16:49 +0100
            Re: White background colour in GCOL is grey. Martin <News03@avisoft.f9.co.uk> - 2021-05-13 17:09 +0100
              Re: White background colour in GCOL is grey. George Pearce <chasgpearce@gmail.com> - 2021-05-13 09:22 -0700
        Re: White background colour in GCOL is grey. J Peachey <john@jpeachey.co.uk> - 2021-05-13 15:04 +0100
        Re: White background colour in GCOL is grey. Steve Fryatt <news@stevefryatt.org.uk> - 2021-05-13 21:52 +0100
          Re: White background colour in GCOL is grey. George Pearce <chasgpearce@gmail.com> - 2021-05-14 02:54 -0700
            Re: White background colour in GCOL is grey. Martin <News03@avisoft.f9.co.uk> - 2021-05-14 11:05 +0100
              Re: White background colour in GCOL is grey. George Pearce <chasgpearce@gmail.com> - 2021-05-14 07:50 -0700

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