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| From | Gr <g@g.com> |
|---|---|
| Newsgroups | comp.lang.c, comp.lang.c++ |
| Subject | Re: datatype for bit flags |
| Date | 2011-09-15 17:24 +0530 |
| Organization | A noiseless patient Spider |
| Message-ID | <j4sp1d$tv7$1@dont-email.me> (permalink) |
| References | <j4s877$2a0$1@dont-email.me> <j4si6f$mmg$1@dont-email.me> |
Cross-posted to 2 groups.
On 15-09-2011 03:26 PM, BartC wrote:
> "Gr" <g@g.com> wrote in message news:j4s877$2a0$1@dont-email.me...
>
>> In the Cohen Sutherland Algorithm of line clipping, a code/flag is
>> using for denoting where an endpoint of the line lies as compared to
>> the clipping rectangle.
>>
>> This code consists of 4 flags (1 each for left, right, below & above).
>>
>> type code = 0;
>>
>> if(point lies to the left of clipping window)
>> code = code & 1;
>> if(point lies to right)
>> code = code & 2;
>>
>> if(point lies below)
>> code = code & 4;
>> if(point lies above)
>> code = code & 8;
>>
>
> I've just looked at my code for this, and I'm using an 'or' operation
> ('|' in C), to build the 'outcode'. In fact looking at your code, your
> 'code' variable is only ever going to be zero.
Yes - I typed that out by mistake - I am using |, not &.
I indicated that in a followup to jacob navia.
>
> As for what type to use for 'code', it probably doesn't really matter.
> Get the whole project working first, then worry about whether that tiny
> aspect is a bottleneck or not.
It's not a project. I am just a looking at the implementation in 2
different text books - one using an unsigned char & the other using an
int & hence wondered about the choices & if one is a better choice than
the other.
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datatype for bit flags Gr <g@g.com> - 2011-09-15 12:37 +0530
Re: datatype for bit flags jacob navia <jacob@spamsink.net> - 2011-09-15 09:26 +0200
Re: datatype for bit flags Gr <g@g.com> - 2011-09-15 13:33 +0530
Re: datatype for bit flags jacob navia <jacob@spamsink.net> - 2011-09-15 10:12 +0200
Re: datatype for bit flags Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-09-15 01:06 -0700
Re: datatype for bit flags "BartC" <bc@freeuk.com> - 2011-09-15 10:56 +0100
Re: datatype for bit flags Gr <g@g.com> - 2011-09-15 17:24 +0530
Re: datatype for bit flags Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-09-16 01:16 +0300
Re: datatype for bit flags Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-09-16 04:59 -0700
Re: datatype for bit flags Jorgen Grahn <grahn+nntp@snipabacken.se> - 2011-09-16 20:46 +0000
Re: datatype for bit flags pete <pfiland@mindspring.com> - 2011-09-16 18:00 -0400
Re: datatype for bit flags Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-09-18 05:00 -0700
Re: datatype for bit flags Jorgen Grahn <grahn+nntp@snipabacken.se> - 2011-09-18 13:36 +0000
Re: datatype for bit flags "Tony" <nospamme@ever.net> - 2011-09-16 16:47 -0500
Re: datatype for bit flags pete <pfiland@mindspring.com> - 2011-09-16 18:35 -0400
Re: datatype for bit flags Keith Thompson <kst-u@mib.org> - 2011-09-16 16:25 -0700
Re: datatype for bit flags pete <pfiland@mindspring.com> - 2011-09-17 02:35 -0400
Re: datatype for bit flags Keith Thompson <kst-u@mib.org> - 2011-09-17 14:42 -0700
Re: datatype for bit flags "Tony" <nospamme@ever.net> - 2011-09-16 19:27 -0500
Re: datatype for bit flags hanukas <jukka@liimatta.org> - 2011-09-23 03:56 -0700
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