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"Slime" <noo### [at] hotmail com> wrote in message
news:3c8557ff$1@news.povray.org...
> I think maybe POV-Ray is treating 1-dimensional light sources > as
two-dimensional ones, thereby checking each point on the
> area light twice. If this is right, it borders on a bug...
I don't think so. I changed the spheres into boxes to see the shadows
better, lifted the light to 2.6 and got the following:
area_light, area 32x1, points 32x1
----------------------------------------------------------
Box 21684326 2200482 10.15
Cone/Cylinder 54435326 54420812 99.97
Plane 56639191 969192 1.71
Bounding Box 339332733 110901120 32.68
Vista Buffer 3909343 2764547 70.72
------------------------------------------------------------
Shadow Ray Tests: 7041549 Succeeded: 2095158
--------------------------------------------------------------
Time For Trace: 0 hours 3 minutes 11.0 seconds (191 seconds)
Notice the Cone/Cylinder intersection tests..
area_light, area 32x1, points 32x2
----------------------------------------------------------
Box 43843409 4878047 11.13
Cone/Cylinder 33295 18794 56.45
Plane 55546322 971544 1.75
Bounding Box 285838244 3696599 1.29
Vista Buffer 3928127 2776387 70.68
----------------------------------------------------------
Shadow Ray Tests: 97865400 Succeeded: 4766193
----------------------------------------------------------
Time For Trace: 0 hours 2 minutes 46.0 seconds (166 seconds)
I guess the extra ray->shape intersection tests come from the lights being
inside the cylinder in the 32x1 points case. Could this be avoided some how?
I don't see why all the test should be done if the light_source is unioned
with a no_shadow object. Using looks_like gives also approximately the same
result as in the 32x1 case.
Ari-Matti
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