Warps: an insanely great concept!

Warps: an insanely great concept!

Post by Robert J. MacG. Daws » Fri, 15 Mar 1996 04:00:00

I have just had time to really play around with POV3 for the first time, over
the last few days. GREAT!  The power of the "Warp" concept is amazing, even
with the few so far devised.  Pigment_maps are fantastic, too! For instance,
try this pigment out: it's a tiled marble floor, in which the tiles look as if
they come from the same quarry but are not cut from two alternating slabs of

==============cut here and render, don't just take my word for it=======
      //Better proofread,  I have to type this in by hand!
#include "colors.inc"

#declare blocky = pigment{
                    [0.1 bozo                   //Branching streaks with color
                        [0 color rgb<0.8,0.6,0.4>]  //between reddish
                        [1 color Brown]}                //and brown
                           scale 5]             //changing slowly;
                    [0.2 bozo           //on a background
                        [0 color White] //between white
                        [1 color rgb<0.7,0.7,0.7>] }     //and tan
                             scale 30]}         //changing very slowly.
                scale <0.1,>             //Shrink it down;
                warp{turbulence 0.7}     //turbulate many layers together
                scale 20                        //and scale back up.
                warp{turbulence 1}              //Ordinary turbulence
                warp{repeat x offset 20.2*y}   //Chop one way...
                warp{repeat z offset 17*y}}      //and the other.

camera{location<1,3,-2> look_at 0}

light_source{<30,30,30> color White}
light_source{<-5,25,-30> color rgb<0.8,0.6,1>}
box<-2,0,-2>,<2,0.2,2> texture{blocky}}

Now, how it works? Several neat tricks made possible by the power of the new
POVRay. Firstly, if a texture is shrunk very small so lots of layers fit into
a small space, turbulence will act similarly on lots of layers. Then if you
blow it up again, the result is a turbulence that distorts the local pattern
comparatively little but changes the angle and scale over biggish distances.
You could do that with marble or wood in POV2 by using a high frequency as
well, but this method works on everything. In particular, crackle makes a
nicely branching marble, as observed by Dan Farmer and others.
        To stop the colors being too homogeneous, I used a very large bozo instead of
a pure color. The result of this is that the vein and background colors change
slowly and independently from place to place.  Finally, I used the "repeat"
warp twice, crossed, with different offsets. This means that every tile is cut
from a very different part of the marble.  You can get an effect a
*little*like this using "tiles" and two different locations in the same marble
texture, but all the "white squares" are really from the same slab, as are all
the "black squares".

          -Robert Dawson


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