POV-Ray : Newsgroups : povray.general : Nested #switch...#end blocks - strange behaviour! Server Time
29 Nov 2024 03:39:54 EST (-0500)
  Nested #switch...#end blocks - strange behaviour! (Message 1 to 5 of 5)  
From: Jörg 'Yadgar' Bleimann
Subject: Nested #switch...#end blocks - strange behaviour!
Date: 15 May 2006 18:55:49
Message: <446906f5$1@news.povray.org>
High!

To differentiate multiple camera views according to the clock variable, 
I set up a logical structure consisting of nested #switch...#end blocks 
- only two levels deep, but a strange effect always occurred: when the 
inner #switch block is reached, only either the first or the last 
alternative is chosen, but not the ones in between. With this test 
script, this means if I start with +k1.1 or +k1.2, I always only got 
"One point ????" as #warning output... and, strangely, obviously line 2 
is interpreted correctly (see output in line 4)! Is this a bug actually?


#declare clock1 = int(clock);
#declare clock2 = mod(clock*10, 10);

#warning concat("clock2 = ", str(clock2, 1, 0))

#switch(clock1)
   #case (0)
     #warning "Zero!"
   #break
   #case (1)
     #switch(clock2)
       #case (0)
         #warning "One point zero!"
       #break
       #case (1)
         #warning "One point one!"
       #break
       #case (2)
         #warning "One point two!"
       #break
       #else
         #warning "One point ????"
     #end
   #break
   #case (2)
     #warning "Two!"
   #break
   #case (3)
     #warning "Three!"
   #break
   #else
     #warning "Oops..."
#end

See you in Khyberspace!

Yadgar


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From: Bob H
Subject: Re: Nested #switch...#end blocks - strange behaviour!
Date: 15 May 2006 19:22:51
Message: <44690d4b@news.povray.org>
Curious thing... apparently it's the mod() doing it because when I replaced 
that part with #declare clock2=1; it works (likewise if clock2=2). And I 
haven't a clue why it would happen like that.


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From: Chris B
Subject: Re: Nested #switch...#end blocks - strange behaviour!
Date: 15 May 2006 20:01:26
Message: <44691656$1@news.povray.org>
"Bob H" <omniverse@charter%net> wrote in message 
news:44690d4b@news.povray.org...
> Curious thing... apparently it's the mod() doing it because when I 
> replaced that part with #declare clock2=1; it works (likewise if 
> clock2=2). And I haven't a clue why it would happen like that.
>

Hi Bob,

I think it's just the usual rounding errors. If you use the integer part of 
the result it works:

    int(mod(clock*10,10))

The cause didn't show up when you used
  #warning concat("clock2 = ", str(clock2, 1, 0))
because this specifies 0 decimal places.
It shows up if you do str(clock2, 1, 30)

Regards,
Chris B.


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From: Bob H
Subject: Re: Nested #switch...#end blocks - strange behaviour!
Date: 15 May 2006 20:13:05
Message: <44691911@news.povray.org>
"Chris B" <c_b### [at] btconnectcomnospam> wrote in message 
news:44691656$1@news.povray.org...
>
> The cause didn't show up when you used
>  #warning concat("clock2 = ", str(clock2, 1, 0))
> because this specifies 0 decimal places.
> It shows up if you do str(clock2, 1, 30)

Wups. Yep, didn't think to look for decimal places.


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From: John VanSickle
Subject: Re: Nested #switch...#end blocks - strange behaviour!
Date: 15 May 2006 22:40:35
Message: <44693ba3$1@news.povray.org>


> High!
> 
> To differentiate multiple camera views according to the clock variable, 
> I set up a logical structure consisting of nested #switch...#end blocks 
> - only two levels deep, but a strange effect always occurred: when the 
> inner #switch block is reached, only either the first or the last 
> alternative is chosen, but not the ones in between. With this test 
> script, this means if I start with +k1.1 or +k1.2, I always only got 
> "One point ????" as #warning output... and, strangely, obviously line 2 
> is interpreted correctly (see output in line 4)! Is this a bug actually?

It could be floating point round-off error.  If you absolutely, 
positively expect it to be an integer, you really need to put floor() 
around any fraction multiplied by anything else.

Regards,
John


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