White background colour in GCOL is grey.

[George Pearce]

Could some kind soul help an ageing forgetful BASIC programmer.

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.

cheers

George Pearce

[Richard Coleman]

Hi George,
I think you might be needing the TINT part, so you would have GCOL 0,191 TINT 192 to get full white.
Details are at http://www.riscos.com/support/developers/bbcbasic/part3/keywords.html#gcol
Thanks,
Richard

[Richard Ashbery]

In article
<912abee8-d3e2-482b...@googlegroups.com>,

GCOL ON 255,255,255 : CLG

Hope that helps

Richard

[Steve Fryatt]

On 12 May, Richard Ashbery wrote in message
<592b7c18...@invalid.addr.uk>:

That's RISC OS 5 only, so doesn't meet the OP's requirement of RISC OS 4
unless soft-loading BASIC is up for consideration.

GCOL 0, 255, 255, 255 : CLG might do what's required, though.

--
Steve Fryatt - Leeds, England

http://www.stevefryatt.org.uk/

[George Pearce]

No, that does not work, screen colour is still black.
It seems to me there is an issue with COL, GCOL in 16 million mode, with no distinction between foreground and background colours, and no palette as such. In 16 and 256 colour modes , colours up to 128 are foreground, and above that are background.
I'm now very confused. I think the BASIC manual needs updating to deal with the larger monitor resolutions we now mostly have, and the entries for COL and GCOL need to address 16million mode.
I understand their application in 16 and 256 colour modes, though I do find the manual a bit confusing.

George Pearce

[Martin]

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.
> > >
> > > GCOL ON 255,255,255 : CLG
> > That's RISC OS 5 only, so doesn't meet the OP's requirement of
> > RISC OS 4 unless soft-loading BASIC is up for consideration.
> >
> > GCOL 0, 255, 255, 255 : CLG might do what's required, though.

> No, that does not work, screen colour is still black.

> It seems to me there is an issue with COL, GCOL in 16 million mode,
> with no distinction between foreground and background colours, and
> no palette as such. In 16 and 256 colour modes , colours up to
> 128 are foreground, and above that are background.

> I'm now very confused. I think the BASIC manual needs updating to
> deal with the larger monitor resolutions we now mostly have, and
> the entries for COL and GCOL need to address 16million mode.

> I understand their application in 16 and 256 colour modes, though I
> do find the manual a bit confusing.

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.

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

[George Pearce]

I did say at the start of my original question it is RISC OS 4.?, as Steve picked up.

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.

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.

Also I'm writing the program for someone who is using RISC OS 4, and would probably demur from soft loading a new OS!

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!

George Pearce

[J Peachey]

In message <bf20a335-0a73-4649...@googlegroups.com>

What about GCOL 0,255 TINT 4. Although the manual implies tint is for
256/16 colour modes it does have an effect on my machine.

Have you tried the basic help - help GCOl which might give you a hint as
to what RO4 can offer?

John

--
_________________________________________
| University of Glos. Blighting Longlevens.
| mailto:jo...@jpeachey.co.uk
_______________________| http://www.jpeachey.co.uk

[News]

In article <ddab484d-c345-461c...@googlegroups.com>,

Have you tried using the colourtrans SWI calls? There are, for
example, ColourTrans_SetGCOL and ColourTrans_SetColour, which work in
all modes.

--
Chris Johnson

[Martin]

In article <ddab484d-c345-461c...@googlegroups.com>,

George Pearce <chasg...@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.

[George Pearce]

Thanks to all for suggestions

To J Peach = GCOL 0,191 TINT 192 seems to work.
To Martin, thanks, I'll have a play with your prog.
To Chris - didn't know about ColourTrans_SetGCOL, and can't fathom at present how to use it to set a white background, but I'll persevere.

Again much thanks to a great community.

[Steve Fryatt]

On 13 May, George Pearce wrote in message
<bf20a335-0a73-4649...@googlegroups.com>:

> It seems to me there is an issue with COL, GCOL in 16 million mode, with
> no distinction between foreground and background colours,

That appears to be the case with the

GCOL mode, r, g, b

form that's in RISC OS 4's BASIC; it's foreground colour only if you want
the RGB option.

The RISC OS 5 version of BASIC (which as I've noted already can be
soft-loaded on to RISC OS 4 systems and is an improvement in a number of
ways) has the

GCOL ON mode, r, g, b

to set the background colour (plus

GCOL OF mode, r, g, b

to explicitly set the foreground).

> and no palette as such.

Correct: the 32k and 16M modes don't have a pallette.

> I think the BASIC manual needs updating to deal with the larger monitor
> resolutions we now mostly have, and the entries for COL and GCOL need to
> address 16million mode.

This has already been done. You can download a PDF from the bottom of

https://www.riscosopen.org/content/downloads/common

but the printed version (which is what I referred to for my comments above
and in my previous post) is well worth the money.

https://www.riscosopen.org/content/sales/bbc-basic-reference

[George Pearce]

I have already bought the excellent new BASIC manual.
I would like to try soft loading the new BASIC into RISC OS 4.39, but can't seem to find it (only complete OS or Harddisc4) or instructions about softloading when found.
I presume it is a module. Will it replace the existing BASIC, or be an addition, and if the latter how is it invoked.

Many thanks for your patience with a doddering 85 year old - I used to know lots of stuff!!

George Pearce

[Martin]

In article <fd28d889-ae22-4103...@googlegroups.com>,

George Pearce <chasg...@gmail.com> wrote:
> I would like to try soft loading the new BASIC into RISC OS 4.39,
> but can't seem to find it (only complete OS or Harddisc4) or
> instructions about softloading when found. I presume it is a
> module. Will it replace the existing BASIC, or be an addition, and
> if the latter how is it invoked.

I have emailed you a zip file which should help.

Martin

[George Pearce]

Thanks Martin
Absolutely brilliant. All seems well on first installation into Virtual Acorn

George