On 8/6/2014 6:36 PM, liujg wrote:
> Alain <kua### [at] videotronca> wrote:

>>> background {
>>>     color rgb < 0.60, 0.70, 0.95 >
>>> }
>>> camera {
>>>     location <0, 15, -60>
>>>    direction <0, 2,  1>
>>>     right x*1.33
>>>    look_at <0,15,0>
>>> }
>>> light_source {
>>>     <0,28,0> // position of a coner of the light plane
>>>     rgb<1.0,1.0,1.0>
>>>     area_light <3, 0, 0>, <0, 3, 0>, 2, 2 // light plane's edges; m by n bulbs
>>>    adaptive 1 // if on, some rays will not be traced
>>>    jitter // randomization of bulb's positions, emulating fuzzy shadow edges
>>> }
>>>
>>
>> The adaptive feature value is NOT a boolean value but an initial or
>> minimal subdivision value.
>> It's turned ON by the sole presence of the keyword "adaptive" followed
>> by some value, even zero.
>>
>> adaptive 0 will shoot at least 4 rays in a 2 by 2 array, the size of
>> your array.
>> adaptive 1 will attempt to shoot at least 9 rays in a 3 by 3 array, but
>> your array, at 2 by 2, is not large enough.
>> adaptive 2 will attempt to shoot at least 25 rays in a 5 by 5 array
>> If a dimention for the sublights is to small in any direction to allow
>> for the desired minimal subdivision, it won't attempt to subdivide further.
>> Using an area_light 3*x, 3*y, 2, 2 with adaptive is totaly pointless.
>>
>> Using this area_light setting is prety fast and gives very smooth results:
>> area_light 3*x, 3*y, 33 33 adaptive 0
>> You can go overboard:
>> area_light 3*x, 3*y, 1025 1025 adaptive 0
>> whitch is almost as fast and so smooth that jitter not usefull.
>>
>>
>>
>> Alain
> Thank you ,My question is that in the render result picture the black area
> should be transparent,because my bitmap have alpha channel .
>
>
You may be misunderstanding the alpha channel, and how it works. We 
would need to see the actually png, to be sure, but.. its not like a 
gif, there isn't just "one color" that functions as an "alpha channel". 
In png, the colors are stored as red, green, blue, alpha. The last one 
can be anything from 100% visible, to 100% see through, and anything in 
between. The only reason why alpha, as far as I know, can possible not 
work in POVRay is if your imagine has the color <0,0,0,0> for the parts 
you want to see through - which would mean Black, 100% visible. I.e., 
the png *may* contain alpha information, but the "color" you are trying 
to see through "does not contain any".

-- 
Commander Vimes: "You take a bunch of people who don't seem any 
different from you and me, but when you add them all together you get 
this sort of huge raving maniac with national borders and an anthem."

Post a reply to this message