Collada Animation Exporter and Importer rework #54456

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Gaia Clary · 2018-03-28T23:30:14+02:00

Gaia Clary commented

2018-03-28 23:30:14 +02:00

It all begun with fixing a few issues... and it ended up in a more or less full rewrite of the animation exporter. and here is what happened (and still happens)

I found that for several years(!) nobody stepped in to work on fixing issues on the animation export part of the Collada exporter (and the importer of course). And i never touched it before. Mainly because i was not at all familiar with all of this. So in January i decided to open the box... OK, for sure i found the well known cans :) What enervated me most was that i just could not find an easy way to fix things on one part without breaking other parts and i not even understood for many parts what actually was happening there.

So i started to cleanup the code and added missing features like support for sampling and export of animated object hierarchies. This first attempt is already running in master but it has some flaws. Especially the exporter repeatedly evaluates the scene on each frame dozens of times and that is not good at all.

Now i have created a second attempt and i just posted it into its own collada branch (derived from master) for now. My goal for now is "make a complete solution, although i know it may be too much. But i am learning things and i like to make complete stuff and not just "it works for me solutions". If someone is interested to take a look then please do:

git checkout -b collada --track origin/collada

The main classes

Basically i have added a class BCAnimationSampler which determines all animations that need to be exported, finds the key frames and or adds sample frames, and steps over the scene animations collecting data samples for every sampled frame and every involved object, material, and bone. It even tracks object animations which are implemented via constraints, finds Camera actions, Lamp actions and Material actions. This BCAnimationSampler is completely independent from Collada and can actually be used for other exporters as well (we could add a python api for this)

How it works:

All exported objects are registered to the Sampler in a loop: sampler->add_object(ob);
The scene is sampled, each sampled frame is evaluated only once: sampler->sample_scene();

Now the sampler can be asked to give the data for any sampled curve for any object: sampler->get_curves(curves, ob);

Performance
The exporter runs about 5 times faster when it comes to exporting a complex character animation (my test animation with 350 bones took about 200 milliseconds with the new system compared to about 1 second with the system as it was before i touched it at all, more precise numbers are to follow).

There are more subclasses like for example the BCAnimationCurve which can be used to easily get the curve data of a specific curve either as a list of floats, or a map<frame,value> or a map <frame, sample>. the BCAnimationCurve also maintains local copies of FCurve objects if necessary. And it gives some limited support for maintaining and exporting curves with tangent information.

It is not yet finished!

However all of this is at the moment in a stage where it just begins to work. So in the next few weeks i will still be busy with getting all of this into a presentable good shape :) However, please feel free to comment and suggest improvements. Especially when it comes to C++ itself i consider myself to still be on the newbie side. But of course also the Blender side is mostly based on my finds in the code itself. So i may easily have overlooked things or made things too complicated...

Here is a first impression of the updated user interface (especially the animation exporter part). I took the FBX Exporter as a guideline:

p.s.: Yes i know there is the "Better collada exporter" and guess what? We also have one for our own purposes :) But this is all about making it complete, and supporting import as well. This is not(!) about "basically works for specific usecase" :)

It all begun with fixing a few issues... and it ended up in a more or less full rewrite of the animation exporter. and here is what happened (and still happens) I found that for several years(!) nobody stepped in to work on fixing issues on the animation export part of the Collada exporter (and the importer of course). And i never touched it before. Mainly because i was not at all familiar with all of this. So in January i decided to open the box... OK, for sure i found the well known cans :) What enervated me most was that i just could not find an easy way to fix things on one part without breaking other parts and i not even understood for many parts what actually was happening there. So i started to cleanup the code and added missing features like support for sampling and export of animated object hierarchies. This first attempt is already running in master but it has some flaws. Especially the exporter repeatedly evaluates the scene on each frame dozens of times and that is not good at all. Now i have created a second attempt and i just posted it into its own collada branch (derived from master) for now. My goal for now is "make a complete solution, although i know it may be too much. But i am learning things and i like to make complete stuff and not just "it works for me solutions". If someone is interested to take a look then please do: ``` git checkout -b collada --track origin/collada ``` **The main classes** Basically i have added a class BCAnimationSampler which determines all animations that need to be exported, finds the key frames and or adds sample frames, and steps over the scene animations collecting data samples for every sampled frame and every involved object, material, and bone. It even tracks object animations which are implemented via constraints, finds Camera actions, Lamp actions and Material actions. This BCAnimationSampler is completely independent from Collada and can actually be used for other exporters as well (we could add a python api for this) **How it works:** - All exported objects are registered to the Sampler in a loop: sampler->add_object(ob); - The scene is sampled, each sampled frame is evaluated only once: sampler->sample_scene(); # Now the sampler can be asked to give the data for any sampled curve for any object: sampler->get_curves(curves, ob); **Performance** The exporter runs about 5 times faster when it comes to exporting a complex character animation (my test animation with 350 bones took about 200 milliseconds with the new system compared to about 1 second with the system as it was before i touched it at all, more precise numbers are to follow). There are more subclasses like for example the BCAnimationCurve which can be used to easily get the curve data of a specific curve either as a list of floats, or a map<frame,value> or a map <frame, sample>. the BCAnimationCurve also maintains local copies of FCurve objects if necessary. And it gives some limited support for maintaining and exporting curves with tangent information. **It is not yet finished!** However all of this is at the moment in a stage where it just begins to work. So in the next few weeks i will still be busy with getting all of this into a presentable good shape :) However, please feel free to comment and suggest improvements. Especially when it comes to C++ itself i consider myself to still be on the newbie side. But of course also the Blender side is mostly based on my finds in the code itself. So i may easily have overlooked things or made things too complicated... Here is a first impression of the updated user interface (especially the animation exporter part). I took the FBX Exporter as a guideline: ![collada.png](https://archive.blender.org/developer/F2530303/collada.png) p.s.: Yes i know there is the "Better collada exporter" and guess what? We also have one for our own purposes :) But this is all about making it complete, and supporting import as well. This is not(!) about "basically works for specific usecase" :)

Gaia Clary self-assigned this 2018-03-28 23:30:15 +02:00

Gaia Clary commented

2018-03-28 23:30:15 +02:00

Added subscriber: @GaiaClary

Gaia Clary changed title from ~~Collada Animation Exporter and Imporeter rework~~ to Collada Animation Exporter and Importer rework

2018-03-29 13:35:22 +02:00

Gaia Clary commented

2018-03-30 23:55:00 +02:00

Right now the exporter support following curve types:

Transformations

4*4 Matrix (as true Matrix data export with 16 entries per sample)
Rotation_euler (single channels, Degree)
Scale (single channels)
Location (single channels)

Material channels

Specular Hardness
Specular color (RGB)
Diffuse Color (RGB)
Alpha
IOR

Lamp channels

Light Color (RGB)
Falloff angle (degree)
Falloff Exponent
Blender distance (using blender profile)

Camera channels

Lens - collada: xfov, combines lens and sensor_x using focallength_to_fov(float focal_length, float sensor)
Sensor_x, Sensor_y - collada: not directly supported, but se Lens above
Orthographic scale - collada: xmag, ymag
Clipping start/end - collada: znear, zfar

Right now the exporter support following curve types: **Transformations** * 4*4 Matrix (as true Matrix data export with 16 entries per sample) * Rotation_euler (single channels, Degree) * Scale (single channels) * Location (single channels) **Material channels** * Specular Hardness * Specular color (RGB) * Diffuse Color (RGB) * Alpha * IOR **Lamp channels** * Light Color (RGB) * Falloff angle (degree) * Falloff Exponent * Blender distance (using blender profile) **Camera channels** * Lens - collada: xfov, combines lens and sensor_x using focallength_to_fov(float focal_length, float sensor) * Sensor_x, Sensor_y - collada: not directly supported, but se Lens above * Orthographic scale - collada: xmag, ymag * Clipping start/end - collada: znear, zfar

Gaia Clary commented

2018-11-26 23:38:19 +01:00

Changed status from 'Open' to: 'Resolved'

Gaia Clary closed this issue

2018-11-26 23:38:19 +01:00

Gaia Clary commented

2018-11-26 23:38:19 +01:00

The Collada module has been reworked and released to the blender2.8 branch. the changes described above have all been added. However there are still some fixes to be done as follow up tasks.

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Collada Animation Exporter and Importer rework #54456

Now the sampler can be asked to give the data for any sampled curve for any object: sampler->get_curves(curves, ob);