[Sidefx-houdini-list] Houdini |world position in expression

Edward Lam edward at sidefx.com
Tue Dec 12 08:35:44 EST 2017


Sorry, Olivier, didn't read your expression close enough. In that case, you can 
do something like:

    vlength(vtorigin("../Real_DOF_cam", "../null_focus"))

The key is that using vtorigin (and friends) will deal with world space and 
therefore takes into account parenting/constraint relationships.

Cheers,
-Edward


On 12/12/2017 4:25 AM, Olivier Jeannel wrote:
> Edward, I'm not super sure how to use the vtorigin. I'm suppose to retrieve
> the camera position and then calculate the distance from the null, no ?
> Gregory, I have no knowledge of python.
> 
> 
> 2017-12-11 18:02 GMT+01:00 Gregory Ecker <gregory.ecker at gmail.com>:
> 
>>   you could also do something in python like:
>>
>> trn = objnode.worldTransform().explode()
>> x = trn['translate'].x()
>>
>> etc.
>>
>> where 'objnode' is a hou.node() of your 'null_focus)
>>
>>
>> On Mon, Dec 11, 2017 at 7:54 AM, Edward Lam <edward at sidefx.com> wrote:
>>
>>> Use something like:
>>>   vtorigin("", "../null_focus")[0]
>>>   vtorigin("", "../null_focus")[1]
>>>   vtorigin("", "../null_focus")[2]
>>>
>>> -Edward
>>>
>>>
>>> On 12/11/2017 7:35 AM, Olivier Jeannel wrote:
>>>
>>>> Hi,
>>>>
>>>> For a Camera that renders with DOF, I'm using an expression in the
>> "Focus
>>>> Distance" field of the camera object.
>>>> distance(ch("../null_focus/tx"),ch("../null_focus/ty"),ch(".
>>>> ./null_focus/tz"),ch("../Real_DOF_cam/tx"),ch("../Real_DOF_c
>>>> am/ty"),ch("../Real_DOF_cam/tz"))
>>>> Where "null_focus" is where the camera ...focusing.
>>>> "Real_DOF_cam" is my camera name.
>>>>
>>>> Everything works well until I parent the camera to a null.
>>>> As soon as I parent the camera and move the null, the results of the DOF
>>>> are completly false.
>>>> I'm wondering what expression I should use to calculate the Focus
>> Distance
>>>> based on the camera world position (as it seems to calculate it in
>>>> local/parented atm).
>>>>
>>>> Thank you !
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