On 28 Jun 2001 15:56:57 -0400, Ron Parker wrote:
>atan2(vdot(A-B,C-B),vlength(vcross(A-B,C-B))) 

...

>I haven't tested either equation, so there are probably embarrassing 
>errors in them.

Well, at least one embarrassing error is that I got those backwards.  You
want atan2(vlength(vcross(A-B,C-B)),vdot(A-B,C-B)).

-- 
plane{-z,-3normal{crackle scale.2#local a=5;#while(a)warp{repeat x flip x}rotate
z*60#local a=a-1;#end translate-9*x}pigment{rgb 1}}light_source{-9red 1rotate 60
*z}light_source{-9rgb y rotate-z*60}light_source{9-z*18rgb z}text{ttf"arial.ttf"
"RP".01,0translate-<.6,.4,.02>pigment{bozo}}light_source{-z*3rgb-.2}//Ron Parker

Post a reply to this message