i'm trying to scale an object for an animation where the object shrinks.
here is what i've tried:

sphere {0,1 pigment {rgb 1} scale 2*(clock+.0001) }
sphere {0,1 pigment {rgb 1} scale -2*(clock+.0001) }
sphere {0,1 pigment {rgb 1} scale (clock+.0001)/2 }
sphere {0,1 pigment {rgb 1} scale (clock+.0001)/.5 }

 the results are always an object that enlarges. does anyone know how i
would scale it to shrink with the clock value?
   thanks in advance,
     jason

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Jason Dinger wrote in message <379d0a19@news.povray.org>...
>i'm trying to scale an object for an animation where the object
shrinks.
>here is what i've tried:
>
>sphere {0,1 pigment {rgb 1} scale 2*(clock+.0001) }
>sphere {0,1 pigment {rgb 1} scale -2*(clock+.0001) }
>sphere {0,1 pigment {rgb 1} scale (clock+.0001)/2 }
>sphere {0,1 pigment {rgb 1} scale (clock+.0001)/.5 }
>
> the results are always an object that enlarges. does anyone know how i
>would scale it to shrink with the clock value?

scale (1-clock)*factor

when clock is 0 the result is 1*factor
as the clock progresses towards 1 this becomes closer to
0*factor

So things will get smaller

HTH

Have Fun
Martin
--
me### [at] tesseractcomau

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There's a completely different technique described in my tutorial "Advanced
POV Animation for Beginners" that allows the use of non-linear clocks as
well as multi-stages, compound clocks and complex paths. Scaling is of
course included in the effects. The tutorial is based on Chris Colefax's
Clock Modifier macro and is very easy to learn.

http://www.puzzlecraft.com/cm/ClockMod.html

steve

Jason Dinger wrote:

> i'm trying to scale an object for an animation where the object shrinks.
> here is what i've tried:
>
> sphere {0,1 pigment {rgb 1} scale 2*(clock+.0001) }
> sphere {0,1 pigment {rgb 1} scale -2*(clock+.0001) }
> sphere {0,1 pigment {rgb 1} scale (clock+.0001)/2 }
> sphere {0,1 pigment {rgb 1} scale (clock+.0001)/.5 }
>
>  the results are always an object that enlarges. does anyone know how i
> would scale it to shrink with the clock value?
>    thanks in advance,
>      jason

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Hej Jason,

here is what you did:
start of animation: clock=0
end   of animation: clock=1

> sphere {0,1 pigment {rgb 1} scale 2*(clock+.0001) }
clock=0    scale 0.0002
clock=1    scale 2.0002

> sphere {0,1 pigment {rgb 1} scale -2*(clock+.0001) }
clock=0    scale -0.0002
clock=1    scale -2.0002
(same as above but mirrored)

> sphere {0,1 pigment {rgb 1} scale (clock+.0001)/2 }
clock=0    scale 0.00005
clock=1    scale 0.50005

> sphere {0,1 pigment {rgb 1} scale (clock+.0001)/.5 }
exactly the same as number 1, because 1/.5=2

Here is what you could do:

linear
sphere {0,1 pigment {rgb 1} scale 1-clock }
clock=0    scale 1
clock=1    scale 0

slow in the beginning
sphere {0,1 pigment {rgb 1} scale 1-clock*clock }
clock=0    scale 1
clock=1    scale 0

fast in the beginning
sphere {0,1 pigment {rgb 1} scale (1-clock)*(1-clock) }
clock=0    scale 1
clock=1    scale 0

slow in the beginning
sphere {0,1 pigment {rgb 1} scale cos(pi*clock) }
clock=0    scale 1
clock=1    scale 0

fast in the middle
sphere {0,1 pigment {rgb 1} scale 0.5+0.5*cos(2*pi*clock) }
clock=0    scale 1
clock=1    scale 0

.....

You can even further modify these examples by including the expression
after "clock" in the equation "pow(<expression>,p)" with different
values for p.
1<p   => slower in the beginning, further acceleration to the end
0<p<1 => acceleration in the beginning, slowing down to the end

Or you could simply modify the range of the clock variable with the
commandline parameters "+KI" and "+KF"...


Uwe.

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