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In article <3c7788f5@news.povray.org>, "Hugo" <hua### [at] post3 teledk>
wrote:
> > (of course I know sphere sweeps are slow in nature).
>
> I wonder why spheresweeps exsist in POV at all.. I may sound negative, but
> these shapes can be achieved with cones and render much quicker! I know that
> extra memory is required, but then .... wouldn't it be possible to code an
> internal "repeating-cones" algoritm in POV ... actually a function that just
> repeats any shape, following a user defined path / formula, *without*
> storing all points in memory first. This would be useful in many cases.
As others have mentioned: memory. Take a curved sweep using enough
spheres and cones to be smooth, and now make a few copies...
I do think other rendering methods would be useful. Some kind of
adaptive subdivision into cones, tesselation, isosurface-type methods,
etc...
I think a lot of the problem is just bad bounding though. A sphere sweep
has a lot of empty space, a box doesn't work that well...some additional
way of rejecting rays that can't intersect would probably help. Maybe a
bounding sweep composed of cylinders or cones...
Followups to povray.programming.
--
Christopher James Huff <chr### [at] maccom>
POV-Ray TAG e-mail: chr### [at] tagpovrayorg
TAG web site: http://tag.povray.org/
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On Sat, 23 Feb 2002 10:05:31 -0500, Christopher James Huff <chr### [at] maccom>
wrote:
> I think a lot of the problem is just bad bounding though. A sphere sweep
> has a lot of empty space, a box doesn't work that well...some additional
> way of rejecting rays that can't intersect would probably help. Maybe a
> bounding sweep composed of cylinders or cones...
If it can help - look at the:
http://news.povray.org/40eq4uc2i1nmgv4tkq9cdhlb1h4cqrofof%404ax.com
I used here four sphere_sweeps and plane. If it can help here is output of
this image. Other types of objects listed in statistic are becouse of trace()
used in placing sphere_sweeps:
Warning: This rendering uses the following experimental feature(s): Spline,
Radiosity. The design and implementation of these features is likely to change
in future versions of POV-Ray. Full backward compatibility with the current
implementation is NOT guaranteed.
Creating bounding slabs.
Scene contains 5 frame level objects; 1 infinite.
----------------------------------------------------------------------------
Pixels: 319210 Samples: 780882 Smpls/Pxl: 2.45
Rays: 6133522 Saved: 0 Max Level: 2/5
----------------------------------------------------------------------------
Ray->Shape Intersection Tests Succeeded Percentage
----------------------------------------------------------------------------
Cone/Cylinder 7767944 13991 0.18
CSG Union 7767944 829839 10.68
Mesh 15549 467 3.00
Plane 7963111 2916648 36.63
Sphere 7767944 4526 0.06
Sphere Sweep 31584064 13614668 43.11
Bounding Box 31390129 28697761 91.42
Light Buffer 2153688 1810792 84.08
Vista Buffer 4690583 4488425 95.69
----------------------------------------------------------------------------
Roots tested: 95447041408 eliminated: 0
Calls to Noise: 0 Calls to DNoise: 10
----------------------------------------------------------------------------
Shadow Ray Tests: 4736594 Succeeded: 1282164
----------------------------------------------------------------------------
Radiosity samples calculated: 66908 (9.45 percent)
Radiosity samples reused: 641309
----------------------------------------------------------------------------
Smallest Alloc: 25 bytes Largest: 785744
Peak memory used: 14994383 bytes
----------------------------------------------------------------------------
Time For Parse: 0 hours 0 minutes 33.0 seconds (33 seconds)
Time For Trace: 223 hours 34 minutes 14.0 seconds (804854 seconds)
Total Time: 223 hours 34 minutes 47.0 seconds (804887 seconds)
ABX
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