the post where someone had a fancy ball flying around and some kind of
"guns" followed him ...

I know it was here a VERY long time ago, and I don't know from whom it was,
but he must have used a macro that takes an location and a target as vectors
and gives back some rotations ...

If someone knows what I mean, please tell me, where I have to look at ...

I have to admit, that I'm currently to lazy to figure this out myself ...
AFAIK it goes like a conversion of cartesian coordinates to polar
coordinates ...
it was something with atan, but IIRC there have been some special cases to
handle when something like x/y was zero ...

I'd prefer to find a macro (of course, I'm sure there is one) ....

ThanX ... Jan

--
Jan Walzer

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Paul Daniel Jones <pdj### [at] psuedu>    auto-tracking [594 Kb]  11303   
10/4/00 7:26 AM
Message-ID: <39DB2206.198A1493@psu.edu>

The message didn't mention anything about the source code though...it 
just mentioned that it was going to be used in a scene.

-- 
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/

<><

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Jan Walzer wrote in message <3a66275e@news.povray.org>...
>the post where someone had a fancy ball flying around and some kind of
>"guns" followed him ...
>
>I know it was here a VERY long time ago, and I don't know from whom it was,
>but he must have used a macro that takes an location and a target as
vectors
>and gives back some rotations ...


I wrote a couple of macros to do that:

#macro Bearing(__Location, __Target)
 degrees(atan2((__Location.z-__Target.z),-(__Location.x-__Target.x)))
#end
#macro Elevation(__Location, __Target)

degrees(atan2((__Target.y-__Location.y),sqrt(sqr(__Location.x-__Target.x)+sq
r(__Location.z-__Target.z))))
#end


Bearing() gives you the rotation around the y axis for the gun turret, and
Elevation() gives you the rotation about the z axis for the gun.  Example:
Your gun turret is at <1,2,3>, and you are shooting at a target at <-5,4,7>:

union{
    object{GunBarrel rotate z*Elevation(<1,2,3>,<-5,4,7>)}
    object{GunTurret}
    rotate y*Bearing(<1,2,3>,<-5,4,7>)
    translate <1,2,3>
}

--
Mark

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Thanx a lot ...

Jan

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I recently rewrite a macro to easily place an object maybe it can help you
or inspire you

The syntax is like :

object { Yourobject transform
putto(refA,refB,norm1,newA,newB,norm2,option) }

refA and ref B  : two points used as starting position
norm1 : if the object need to be oriented this vector is orthogonal to
vector(ptB-ptA)

newA , new B ,norm2  : final position
option : scling type ( 0 uniform scaling )

example :
"fleche" is an arrow build between the points -1*x, 1*x
to place it between two points A and B write :

object { fleche transform putto(-1*x,1*x,0,A,B,0,0) material { example }}

"normal vector" are 0 because fleche don't need orientaion : it is an object
of revolution

I use this macro a lot to copy a same object between multiple position.

I hope this could help

Sorry for my english

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Attachments:
Download 'img0.jpg' (3 KB) Download 'img1.jpg' (3 KB) Download 'img2.jpg' (5 KB) Download 'macroputto.inc.txt' (7 KB) Download 'mopspatch.inc.txt' (15 KB) Download 'putto_ex.pov.txt' (4 KB)

Preview of image 'img0.jpg'

Preview of image 'img1.jpg'

Preview of image 'img2.jpg'

Hi m.o.p.s.

Could you please cancel your post here at povray.binaries.animations?  The
message would be better placed at povray.binaries.scene-files group instead of
here.  I see that Thorsten Froehlich has already moved your other message post
to povray.general but it really belongs at povray.binaries.scene-files in
whole.  Separate images going to povray.binaries.images with a mention of the
p.b.s-f. message might be another thing to do.

Thanks.

Bob H.

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