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Marc Champagne posts in p.general a picture and a short scene of one
bogus blob for 3.5
I convert it to a scene of 3.1 and try it.
The bug was already there.
The good news is that the bug is due to the 'convex hull optimisation'
(whatever it can be) in the blob code.
The sad news is that I do not understand the math used for this bogus thing.
So, have a look and cry!!!!
Here the code for 3.1:
#version 3.1;
#declare image_width=640;
#declare image_height=640;
global_settings { assumed_gamma 1.0 }
camera {
location <3, 3, -3>
direction 1.5*z
right x*image_width/image_height
look_at <0,1,0>
}
light_source {
<0, -10, -250>
rgb 2
// cylinder
// parallel
//point_at <0,0,0>
}
#declare T = 1 ;
#declare S = 1 ;
blob {
threshold T
sphere { < 0, 0, 0 >, 1, S }
sphere { < -1, 1, 0 >, 1, S }
sphere { < 0, 1, 1 >, 1, S }
sphere { < 0, 1, 0 >, 1, S }
sphere { < 0, 1,-1 >, 1, S }
sphere { < 1, 1, 0 >, 1, S }
sphere { < 0, 2, 0 >, 1, S }
sturm
pigment { rgb < .4, 0, 0 > }
finish { ambient .7 diffuse .3 }
}
#################################
And two images: one from 3.1, and the same from patched code so as to
comment out the optimisation (as suggested during 3.5 beta, french
reader can get more information at
http://jgrimbert.free.fr/pov/correct/blobc.html
)
Have a nice day!
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Attachments:
Download 'blob.png' (26 KB)
Download 'blobg+.png' (26 KB)
Preview of image 'blob.png'
Preview of image 'blobg+.png'
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hughes, b. wrote:
> Seems self-evident. Was there a significant render time change? I have to
> ask that since the operative word mentioned was "optimisation".
Yes, due to the nearly mandatory "sturm" and to the increase of the
number of root-solving (before, when the ray it the bounding box, the
root solving could have been avoided thanks to a 'simple' if [but that
if is currently bogus).
>
> I didn't get the same image output using v3.5 as shown on the web page you
> gave and using the accompanying script.
Only the top two images were done with unmodified 3.1;
The four images at the bottom were done with the patch, that you do not
have, so of course, you cannot get the same picture.
If the two top images are also different with 3.5 (excepted for any
gamma correction), then some default values must have been updated from
3.1 to 3.5 (
or do I need to try them in 3.5 ? I'm a bit lazy right now :-)
>
> Is this only the version directive used to get a 3.1 image here, or did you
> put it through POV 3.1? Sorry, but I couldn't figure that out from what you
> said.
I put it through 3.1
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