> 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 .
>
>

Your image DOES have an alpha channel, but that channel say "this pixel 
have zero transparency" everywhere. If the alpha channel was correct, 
then Thunderbird would show the background colour of the page instead of 
black. Also, in the web version, just any browser should also show the 
black areas as transparent, meaning that any background will show 
through. This _IS NOT THE CASE_ with your image !

The fact that a given pixel is black *never ever* make it transparent. 
In fact, it can be absolutely any colour of the 16.4 millions available.




Alain

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