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

Olivier Jeannel facialdeluxe at gmail.com
Tue Dec 12 09:29:16 EST 2017


Perfect ! Thank's a lot Edward !

2017-12-12 14:35 GMT+01:00 Edward Lam <edward at sidefx.com>:

> 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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