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

[Bartek Skorupa]

Tried it and it doesn't work unfortunately.
It simply doesn't update :-(
Tried with a default scene where I added keyframes for cube's location  
and printed locations for every frame. It showed exactly the same  
values throughout the animation.

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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