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Re: Rotating a Colour-Filled Square

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Am Thu, 14 Nov 2019 16:24:43 +0000 schrieb Richard Ashbery:

> In article <qqjgq3$dkd$1@solani.org>, Sebastian Barthel
> <naitsabes@freenet.de> wrote:
>> Am Wed, 13 Nov 2019 23:35:41 +0000 schrieb Sebastian Barthel:
> 
>> > Am Wed, 13 Nov 2019 17:05:44 +0000 schrieb Richard Ashbery:
>> > 
>> >> ... but what I'm really after is a method to overlay the existing
>> >> square with other successively smaller squares in alternating
>> >> colours.
>> > 
>> > 
>> > To find a point where the FILL can start in a defined way, I sorted
>> > the X-values and used the one on the left side (XMIN). ...
> 
>> This can and probably should be changed to a variant wich calculates
>> the startpoint for the FILL command directly.
> 
>> To find such a point You could do an
> 
>>  XMIN=SIN(ANGLE)*(F-8) : XMINY=COS(ANGLE)*(F-8) FILL XMIN,XMINY
> 
>> and delete all the other lines wich include XMIN or XMINY.
> 
> It gets better :-) Implemented above which saves 4 lines of code. Came
> up with an error to start with but error routine gives no hint as to
> what might be wrong. I've found the following more helpful...
> 
> ON ERROR REPORT : PRINT " at line ";ERL : END

Yes, that's the "more informative" way to produce an error message. But 
it's only a miniroutine and then I couldn't remember how to print the 
message (REPORT). But: Sometimes its better not to know the name of the 
error - so one gets a chance to find it by himself ... (OK; that's 
nonsense ;) ...)


The error is the missing ":" in front of the FILL command.
( That's a "special feature" of the Newsreader wich likes to concatenate 
lines together in a single line - especially if they are exported from 
RISC OS to Unix textformats. )


> There's a lot of information here - I've got the basics but I'll need
> some time to digest it all.

OK, think about it.
Has to do much with the way in wich the fill routine works. So it depends.

 
> As it stands I'm not sure that double-buffering will be enough to really
> improve its smoothness - I believe there's something called triple
> buffering - would this work I wonder?

Double Buffering will produce an un-flickery picture. That's all.
To increase the "smoothness" I would change the STEP parameter S - for 
instance to 3 degrees; S=RAD(3)

 
> This is turning out to be a rather nice little animation. Keep up the
> good work. I think it needs more squares (bearing in mind the overlap
> issue blanking out the colour) and a larger colour range but is pretty
> good as it is. An intesting effect is the rotation speed variation -
> probably due to the # of sine/cosine calculations required.

Yes, looks fine as an effect.

The speed variation isn't there, not really ... it's not an intended or 
programmed one. It's only an optical effect wich is partly reasoned by 
the changes in the direction of the rotation (clockwise, 
counterclockwise) between the different layers of squares.

This gets more interesting with more layers and/or higher values for the 
"rotation variance" ( the factor "*7" in the line where ANGLE is 
recalculated).


> This is
> obviously what you meant when you said routine needs speeding up with an
> array function to work out all the values before doing the rotation.
> Could this be a feature perhaps :-)

This could be a feature.
We'll see if it finds its way into reality.

> When "perfected" can I put it on my website?

Yes, you can. It's not that exclusive and there are many 80's Demos wich 
demonstrated it long before 2019.

Eventually anybody else can find an interesting way to choose the 
colours. Rainbow colors or something TIME variable based.


All the best,
SBn

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Thread

Rotating a Colour-Filled Square Richard Ashbery <basura@invalid.addr.uk> - 2019-11-12 14:05 +0000
  Re: Rotating a Colour-Filled Square Sebastian Barthel <naitsabes@freenet.de> - 2019-11-12 23:04 +0000
    Re: Rotating a Colour-Filled Square Richard Ashbery <basura@invalid.addr.uk> - 2019-11-14 16:24 +0000
      Re: Rotating a Colour-Filled Square Sebastian Barthel <naitsabes@freenet.de> - 2019-11-14 19:29 +0000
        Re: Rotating a Colour-Filled Square Sebastian Barthel <naitsabes@freenet.de> - 2019-11-15 21:26 +0000
        Re: Rotating a Colour-Filled Square Sebastian Barthel <naitsabes@freenet.de> - 2019-11-15 22:23 +0000
          Re: Rotating a Colour-Filled Square Sebastian Barthel <naitsabes@freenet.de> - 2019-11-15 22:31 +0000
            Re: Rotating a Colour-Filled Square Richard Ashbery <basura@invalid.addr.uk> - 2019-11-16 14:05 +0000
              Re: Rotating a Colour-Filled Square Sebastian Barthel <naitsabes@freenet.de> - 2019-11-16 19:47 +0000
                Re: Rotating a Colour-Filled Square druck <news@druck.org.uk> - 2019-11-18 20:02 +0000
          Re: Rotating a Colour-Filled Square Steve Fryatt <news@stevefryatt.org.uk> - 2019-11-16 00:39 +0000
            Re: Rotating a Colour-Filled Square Richard Ashbery <basura@invalid.addr.uk> - 2019-11-16 12:21 +0000
              Re: Rotating a Colour-Filled Square Steve Fryatt <news@stevefryatt.org.uk> - 2019-11-17 10:04 +0000
                Re: Rotating a Colour-Filled Square Richard Ashbery <basura@invalid.addr.uk> - 2019-11-17 13:50 +0000
                Re: Rotating a Colour-Filled Square Richard Ashbery <basura@invalid.addr.uk> - 2019-11-17 14:19 +0000
                Re: Rotating a Colour-Filled Square Steve Fryatt <news@stevefryatt.org.uk> - 2019-11-17 14:21 +0000
                Re: Rotating a Colour-Filled Square Richard Ashbery <basura@invalid.addr.uk> - 2019-11-17 15:34 +0000
                Re: Rotating a Colour-Filled Square Steve Fryatt <news@stevefryatt.org.uk> - 2019-11-17 16:25 +0000
                Re: Rotating a Colour-Filled Square Richard Ashbery <basura@invalid.addr.uk> - 2019-11-18 16:17 +0000
                Re: Rotating a Colour-Filled Square Richard Ashbery <basura@invalid.addr.uk> - 2019-11-18 16:55 +0000
          Re: Rotating a Colour-Filled Square druck <news@druck.org.uk> - 2019-11-16 11:48 +0000
            Re: Rotating a Colour-Filled Square Richard Ashbery <basura@invalid.addr.uk> - 2019-11-16 14:21 +0000
              Re: Rotating a Colour-Filled Square druck <news@druck.org.uk> - 2019-11-18 20:04 +0000
                Re: Rotating a Colour-Filled Square Richard Ashbery <basura@invalid.addr.uk> - 2019-11-19 14:48 +0000
                Re: Rotating a Colour-Filled Square druck <news@druck.org.uk> - 2019-11-19 20:26 +0000
                Re: Rotating a Colour-Filled Square Brian Jordan <brian.jordan9@btinternet.com> - 2019-11-19 20:39 +0000
                Re: Rotating a Colour-Filled Square Dave <dave@triffid.co.uk> - 2019-11-20 07:50 +0000
                Re: Rotating a Colour-Filled Square Alan Adams <alan@adamshome.org.uk> - 2019-11-20 11:26 +0000
            Re: Rotating a Colour-Filled Square Sebastian Barthel <naitsabes@freenet.de> - 2019-11-16 19:27 +0000
              Re: Rotating a Colour-Filled Square Steve Fryatt <news@stevefryatt.org.uk> - 2019-11-16 23:37 +0000
      Re: Rotating a Colour-Filled Square druck <news@druck.org.uk> - 2019-11-14 20:47 +0000
    Re: Rotating a Colour-Filled Square druck <news@druck.org.uk> - 2019-11-14 20:44 +0000
      Re: Rotating a Colour-Filled Square Richard Ashbery <basura@invalid.addr.uk> - 2019-11-15 13:35 +0000
        Re: Rotating a Colour-Filled Square Steve Fryatt <news@stevefryatt.org.uk> - 2019-11-16 00:32 +0000
    Re: Rotating a Colour-Filled Square Richard Ashbery <basura@invalid.addr.uk> - 2019-11-13 12:54 +0000
      Re: Rotating a Colour-Filled Square Richard Ashbery <basura@invalid.addr.uk> - 2019-11-13 17:05 +0000
        Re: Rotating a Colour-Filled Square Sebastian Barthel <naitsabes@freenet.de> - 2019-11-13 23:35 +0000
          Re: Rotating a Colour-Filled Square Sebastian Barthel <naitsabes@freenet.de> - 2019-11-14 12:20 +0000
          Re: Rotating a Colour-Filled Square Richard Ashbery <basura@invalid.addr.uk> - 2019-11-14 14:09 +0000
  Re: Rotating a Colour-Filled Square Richard Ashbery <basura@invalid.addr.uk> - 2019-11-14 15:21 +0000
  Re: Rotating a Colour-Filled Square news@sprow.co.uk - 2019-11-14 05:00 -0800

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