[Bf-committers] bpy.context.scene.frame_set(i) issue

[Bartek Skorupa]

Thank you very much for that.
I will try it and maybe it will do the trick.
I wonder however if it updates objects when their matrices depend on  
other objects not included in selection (parenting, constraints, etc).
Anyway, thank you very much, I'll see if it improves anything.


Bartek Skorupa

www.bartekskorupa.com

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On 2012-01-21, at 11:54, Campbell Barton wrote:

> frame_set() updates all layers of the scene which I expect is the  
> problem here,
>
> there could be an optional argument to pass a layer list to
> frame_set()  but this doesn't necessarily help if the current scene
> layers are not setup efficiently.
>
> looking into this you could update only the objects you want like  
> this...
>
> # objects to update
> objects = bpy.context.selected_objects
> scene = bpy.context.scene
> start = scene.frame_start
> end = scene.frame_end
> for frame in range (start, end + 1):
>    scene.frame_current = frame
>    for obj in objects:
>        obj.update_tag(refresh={'OBJECT'})  # 'DATA' too if you care
> about geometry
>    scene.update()
>    '''
>    .... all the magic that needs data for each frame ....
>    '''
>
>
> On Sat, Jan 21, 2012 at 7:56 PM, Bartek Skorupa
> <bartekskorupa at bartekskorupa.com> wrote:
>> 1. Take any scene that plays back 1 frame per second or so. (I can't
>> upload any example now, but I'm sure everybody has such scene
>> somewhere). Many objects (2000?, 3000?), constraints, shapekeys,
>> armatures, curves etc.
>> 2. No matter if the layers are active or not, no matter what the draw
>> mode is etc - it is slow. I can place all of my obs in layer 2,
>> activate only empty layer 1, and it doesn't influence the speed.
>> 3. Even if frame_set() is as fast as playback - I'm not happy. 250
>> frames - 1 frame per second = 250sec. = 4 minutes. Who wants to  
>> wait 4
>> minutes?
>>
>> Bartek Skorupa
>>
>> www.bartekskorupa.com
>>
>>
>> On 2012-01-21, at 00:58, Campbell Barton wrote:
>>
>>> Hi Bartek,
>>>
>>> Would you be able to upload a test scene which is unusably slow?
>>> can't see why this would be any slower then playing back the  
>>> animation
>>> (if anything should be faster since it doesn't have to draw).
>>>
>>> On Sat, Jan 21, 2012 at 9:58 AM, Bartek Skorupa
>>> <bartekskorupa at bartekskorupa.com> wrote:
>>>> Hi,
>>>>
>>>> I'd like to draw your attention to frame_set(i) method.
>>>> In many scripts we have to refresh the scene several times,  
>>>> sometimes
>>>> we need to collect some data for every frame in the whole  
>>>> animation.
>>>> In such cases the only way I know in blender's python is to set the
>>>> frame using bpy.context.scene.frame_set(frame)
>>>> Almost every exporter that base on baking the data and exporting  
>>>> them
>>>> as "keyframe for every frame" use this kind of loop:
>>>>
>>>> start = bpy.context.scene.frame_start
>>>> end = bpy.context.scene.frame_end
>>>> for frame in range (start, end + 1):
>>>>     bpy.context.scene.frame_set(frame)
>>>>     '''
>>>>     .... all the magic that needs data for each frame ....
>>>>     '''
>>>>
>>>> My exporter to Adobe After Effects (io_export_after_effects.py)  
>>>> does
>>>> exactly the same.
>>>>
>>>> The issue here is that setting the frame sometimes takes ages.
>>>> I was once advised to use bpy.context.frame_current = frame
>>>> Well... It's very fast, but doesn't do the trick. It sets the  
>>>> frame,
>>>> but doesn't update the scene and in most cases - this is what we  
>>>> want
>>>> - We want to have our scene refreshed for every frame.
>>>>
>>>> bpy.context.scene.frame_set(frame) method is so slow, that many
>>>> exporters become almost useless or if not useless - very badly
>>>> perceived because of their performance.
>>>> The process of simple export to After Effects can sometimes take
>>>> several minutes and this is definitely not the performance we are
>>>> looking for.
>>>> I looked through many existing exporters and they all use this
>>>> method,
>>>> so I suppose I'm not the only one facing "frame_set" speed issue.
>>>> Does anyone know other method to achieve refreshing the scene for
>>>> every frame, but not that slow?
>>>>
>>>> Isn't this performance a bug of some kind?
>>>>
>>>> I'd appreciate any help.
>>>>
>>>> Cheers,
>>>> Bartek Skorupa
>>>>
>>>> www.bartekskorupa.com
>>>>
>>>> _______________________________________________
>>>> Bf-committers mailing list
>>>> Bf-committers at blender.org
>>>> http://lists.blender.org/mailman/listinfo/bf-committers
>>>
>>>
>>>
>>> --
>>> - Campbell
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>
>
> -- 
> - Campbell
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