Tim Attwood wrote:

<snip>
> 
> Ok, the problem is that macros aren't full subroutines like you might
> expect. For example
> 
> #macro example(a)
>   #if (a=0)
>    <1,0,0,0>
>   #else
>    <0,0,0,0>
>   #end
> #end
> 
> Parses into this when the macro is evaluated...
> 
>   #if (a=0)
>    <1,0,0,0>
>   #else
>    <0,0,0,0>
>   #end
> 
> And at this level everything needs to be legal, it chokes.
> The solution is to dump everything into #locals..
> 
> #macro Quaternion(Angle,Vector)   // creates a normalized rotation
>  quaternion... angle in radians
>          #if (vlength(Vector)=0)
>           #warning "0 vector not allowed\nUsing identity Quaternion"
>           #local A = 1;
>           #local V = <0,0,0>;
>          #else
>           #local A = cos(Angle/2);
>           #local V = sin(Angle/2)*vnormalize(Vector);
>          #end
>        <A,V.x,V.y,V.z>
> #end
> 
> ----- Tim Attwood -----

Seems to work, haven't tested what happens when I use a zero vector.  
Thanks.  

-- 
Dan Johnson 

http://www.geocities.com/zapob

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