Danny nous apporta ses lumieres ainsi en ce 2004/05/27 23:04... :

>Alain <aze### [at] qwertygov> wrote:
>  
>
>>Danny nous apporta ses lumieres ainsi en ce 2004/05/21 16:22... :
>>
>>    
>>
>>><snip>
>>>
>>>
>>>Is this cylinder light_source supposed to produce a visible light beam that
>>>can be seen outside where it's pointing at, or is it more like a laser pen
>>>that produces a dot on the surface it's aimed at? I tried it along with
>>>scattering and it did nothing to get rid of the images.
>>>Also, in order to round off the ends of my laser beam, I put some
>>>half-spheres on either end, both filled with the same media, except the
>>>density is spherical instead of cylindrical.  For some reason, this created
>>>tons more problems.  When you look at the half-spheres perpendicularly,
>>>there's no problem, but when you look at them obliquely, you get very odd
>>>results, such as grey rings, spots, etc.  Here's what I'm doing:
>>>
>>>
>>>
>>>      
>>>
>>Why do you use this default texture, it's the source of most of your
>>problems
>>
>>    
>>
>>>#default {
>>>  texture {
>>> pigment {Grey}
>>>   finish {
>>>    diffuse 0.6
>>>     ior 1.5
>>>     ambient 0.300000
>>>     phong 0.5
>>>     phong_size 50
>>>}
>>>}}
>>>
>>>
>>>camera {
>>> location <0,0.5,2>
>>> look_at <0,0.5,0>
>>>}
>>>
>>>background {color rgb <0,0,0>}
>>>
>>>light_source {
>>> <-1000.000000,1000.000000,1000.000000>       //  x=-1000,y=1000,z=1000
>>> color rgb <1.0000,1.0000,1.0000>
>>>          }
>>>
>>>#declare clock1=1;
>>>
>>>union{
>>>cylinder{<0,2*clock1,0>,<0,0,0>, 1                 //the laser, top right
>>>      
>>>
>>>from front
>>    
>>
>>>        texture {
>>>   pigment { color rgbt 1}}
>>>      interior{media{emission rgb 1
>>>      density{ cylindrical
>>>      color_map{[0 rgb 0][0.03 rgb <0.0004,0,0>][0.6 rgb<8,0,0>][0.98 rgb
>>>16][1 rgb 30]} //[0 rgb 0][0.02 rgb <0.004,0,0>][0.5 rgb<4,0,0>][0.96 rgb
>>>5][1 rgb 10]
>>>      }}}
>>>      hollow
>>>      scale<0.1, 1, 0.1>
>>>      }
>>>
>>>
>>>      
>>>
>>removing this don't change anything in your cene
>>
>>    
>>
>>>difference{
>>>sphere{<0,0,0>, 1
>>>        texture {
>>>   pigment { color rgbt 1}}
>>>      interior{media{emission rgb 1
>>>      scattering{3,1}
>>>      density{ spherical
>>>      color_map{[0 rgb 0][0.03 rgb <0.0004,0,0>][0.6 rgb<8,0,0>][0.98 rgb
>>>16][1 rgb 30]}
>>>      }}}
>>>      hollow
>>>      scale<0.1, 0.1, 0.1>
>>>      translate <0,2*clock1,0>
>>>      }
>>>cylinder{<0,2*clock1,0>,<0,0,0>,5}
>>>      }
>>>
>>>
>>>      
>>>
>>-----------------------------------------------------------------
>>
>>    
>>
>>>difference{
>>>sphere{<0,0,0>, 1
>>>        texture {
>>>   pigment { color rgbt 1}}
>>>      interior{media{emission rgb 1
>>>      density{ spherical
>>>      color_map{[0 rgb 0][0.03 rgb <0.0004,0,0>][0.6 rgb<8,0,0>][0.98 rgb
>>>16][1 rgb 30]}
>>>      }}}
>>>      hollow
>>>      scale<0.1, 0.1, 0.1>
>>>      }
>>>cylinder{<0,5,0>,<0,0,0>,5}
>>>       }
>>>light_source{0 rgb 10 cylinder point_at y*2}
>>>}
>>>
>>>sphere{<.2,.5,-.5>,0.1}
>>>
>>>
>>>Try running this and you'll see the image of the sphere on the laser.
>>>
>>>
>>>      
>>>
>>Default ior applied to the cylinder
>>
>>    
>>
>>>You'll also see the grey ring where the laser cylinder and the laser
>>>half-sphere meet(try looking at that location perpendicularly and the grey
>>>ring disappears).
>>>
>>>
>>>      
>>>
>>Default texture applied to the substracting cylinder
>>
>>    
>>
>>>You can also see a small white dot on the bottom half-sphere, which is also
>>>an image of the grey sphere.
>>>
>>>      
>>>
>>Default texture's ior again
>>
>>    
>>
>>>I have a background of stars, and so the ends
>>>of my laser end up looking speckled.  How can I make all those images and
>>>grey rings go away?
>>>
>>>
>>>
>>>      
>>>
>>1- Remove the ior statement in your default. Thin add an ior to your
>>cylinder, this is what cause the sphere to apears in your beam.
>>2- Use merge instead on an union. This will remove the internal surfaces.
>>3- Use difference{sphere{...}cylinder{...}texture{...}interior{...}}.
>>That is, apply the texture and interior to the whole
>>union/difference/intersection/merge. The cylinder get the default
>>texture and apply it to where it intercect the sphere, giving you that
>>gray circle.
>>
>>Alain
>>    
>>
>
>
>Thanks, Alain, all the images on the laser are gone now that ior has been
>deleted. It also helped by making the outer edge fuzzier.  However, I'm
>still having problems with the grey circle. This time, instead of a grey
>circle, there's a disk that matches the color of the media (white in the
>middle, red on the outside), but a little wider than the laser so it
>doesn't match up (probably b/c removing the ior also seemed to shrink the
>laser's width a little). Is this what you wanted me to do:
>
>merge{
>  
>
OK

>cylinder{<0,2*clock1,0>,<0,0,0>, 1                 //the laser, top right
>   //      texture {
>   // pigment { color rgbt 1}}
>       interior{media{emission rgb 1
>       density{ cylindrical
>       color_map{[0 rgb 0][0.03 rgb <0.0004,0,0>][0.6 rgb<8,0,0>][0.98 rgb
>16][1 rgb 30]}
>       }}}
>       hollow
>       scale<0.1, 1, 0.1>
>       }
>
>difference{
>sphere{<0,0,0>, 1}
>cylinder{<0,5,0>,<0,0,0>,5}
>  
>
Why is it so large? cylinder{<0,1.1,0>,<0,0,0>,1.1} is large enough
center your sphere and cylinder about <0,0.000001,0> is better, remove 
coincidence surfaces.

>   //      texture {
>   // pigment { color rgbt 1}}
>       interior{media{emission rgb 1
>       density{ spherical
>       color_map{[0 rgb 0][0.03 rgb <0.0004,0,0>][0.6 rgb<8,0,0>][0.98 rgb
>16][1 rgb 30]}
>       }}}
>       hollow
>       scale<0.1, 0.1, 0.1>
>          }
>  
>
    texture{pigment{rgbt 1}finish{ambient 0 diffuse 0}}// apply texture 
once to whole merge

>}
>
Now, I don't see a discontinuity, as long as I stay with a point of view 
close to perpendiculat near the base, even zooming in, smooth trensition.

Alain

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