unsigned short color from RGB

[BadBazza]

[MirekCz]

[BadBazza]

Thanks Mirek,<br><br>For anyone else reading this post the topic is "Easyce stuff" in "Phantoms forum" and is well worth reading.<br><br>How would I impletement a macro to do this? I would like to call vline() as follows:-<br>vline(x,y,len,RGB(255,0,0));<br><br>is the following the correct syntax?<br><br>#define RGB(r,g,b) ((unsigned short)((r<<11)+(g<<5)+(b))<br><br>or the faster version<br>#define RGB(r,g,b) ((unsigned short)((r>>8 )&0xF800)+((g>>5)&0x07E0)+((b>>3)&0x001F)) <br><br>and is this the best way to code a solution. <br><br>Thanks in advance <br>Bad<br><br>PS I've never used macros before so please feel free to correct my syntax or tell me not to use them <br><br>PPS I'm not sure about the 2nd #define at all.<br>Last modification: BadBazza - 01/04/02 at 04:20:01

[MirekCz]

nah you didn't really get it<br>it should be like<br>#define RGB(r,g,b) ((unsigned short)(((r<<8)&0xf800)+((g<<3)&0x07e0)+(g>>3));<br><br>ps. I rarely define macros so not sure if it's correct, but i think so.<br>hope it works correct (didn't test it)

[MirekCz]

the darn face should be "8 )" , sorry...

[BadBazza]

Thanks again Mirek,<br><br>I think I was going the wrong way. Just to check<br><br>#define RGB(r,g,b) ((unsigned short)(((r<<8 )&0xf800)+((g<<3)&0x07e0)+(g>>3)); <br><br>is ((g<<3)&0x07e0) and (g>>3) part of the macro correct?<br><br>Thanks in advance<br>Bad

[Dan East]

Some general define tips:<br><br>Don't put a semicolon at the end - that will cause compilation errors depending on how the macro is used. The way you want to use it as a function parameter would cause errors. Also, you should technically enclose each var in parenthesis like ((a)*(b)), because in a macro what you pass for each var is simply substituted for the var name. You should also enclose the entire expression in parenthesis, which you are already doing.<br><br>For example:<br>[fixed]<br>#define sqr( a ) ( a * a )<br>int i=sqr( 5 + j );<br>[/fixed]<br>The preprocessor would convert that to:<br>[fixed]int i=( 5 + j * 5 + j );[/fixed]<br><br>So operator precedence would not be correct. <br><br>[fixed]<br>#define sqr( a ) ( ( a ) * ( a ) )<br>int i=sqr( 5 + j );<br>[/fixed]<br>The preprocessor would convert that to:<br>[fixed]int i=( ( 5 + j ) * ( 5 + j ) );[/fixed]<br><br>Which is the desired result.<br><br>Dan East

[BadBazza]

Dan,<br><br>Thanks for those tips, do you agree with Mirek's macro?<br><br>#define RGB(r,g,b) ((unsigned short)((((r)<<8 )&0xf800)+(((g)<<3)&0x07e0)+((g)>>3)) <br><br>Thanks in advance<br>Bad<br><br>PS You have done a good job with DeXplor, I will be registering it when I upgrade to PPC2002

[Dan East]

Looks fine to me!<br><br>Dan East

[Digby]

The macro is wrong.  The last g should be a b.<br><br>

[BadBazza]

Mirek, Digby and Dan - Thank you<br><br>All is working beautifully now, the (g) should of been a (b) and there was a closing bracket missing off the end. I have not thouroghly tested it but I have tried rgb(255,0,0), rgb(0,255,0) and rgb(0,0,255) and they produce what I would expect. For those interested the final macro is <br><br>#define rgb(r,g,b) ((unsigned short)((((r)<<8 ) &0xf800) +(((g)<<3)&0x07e0)+((b)>>3)))<br><br>Note 1: remove the space between the 8 and the )<br>Note 2: I had to use rgb instead of RGB as it looks like RGB is defined in wingdi.h<br><br>Thanks again for your help<br>Bad<br>

[MirekCz]

hehe,damn, yeah, stupid mistake with g/b, sorry about that:) I was kinda sleepy at the time of writing it;P <br>Thnx Digby for correcting me.