Experimental Features

[Mike3D]

I've pushed to my fork (https://github.com/Mike3D/Urho3D-Blender) some experimental features:

• prefabs export (individual, collective and scene) There is an option to generate physics. Currently it uses a triangleMesh shape. For non-individual prefabs it expects a unic "Physics.mdl" model. Maybe we could later use blender physics settings.
• preserve parent-child hierarchy for StaticModels
• do not export skeleton and 1.0 weights for objects parented to a single bone. We'd better parent them to their node in the Editor.
• selective tangent export by checking if we are using normal maps (no tangent if no normal map; maybe we could make this as an option or display a warning)
• use material custom properties to set shader parameters (here we have used vegetation technique)
• new documentation style (WIP)

Note that I'm using a custom folder structure based on Scene name for my exports, so you can skip this by checking the "Use Urho standard folder" in the Export panel. Prefabs are exported to "TestScenes" and "TestObjects" folders. You can rename them without "Test" if needed.

Everything should work fine, but don't hesitate to report bugs and provide feedback. Happy testing.

Todo:

• optional binary files for xml files
• improve documentation

[reattiva]

Thanks, sincerely I don't have much time for the exporter. After a quick look I'd say I cannot import your code directly because it seems to be customized for your personal use (of course) and commits do not separate the features added. A pull request with only the cleaned, generic and important bits (and based on the latest master commit) would be perfect, otherwise I'll do a selective merge, it'll require some time. In the meantime, I'll leave this issue open so others can find your link and the list of features added.

For the documentation, the Github wiki seems good, less text more images is optimal.

Mmm, also not to be polemic, but you have removed a feature you have asked here https://github.com/reattiva/Urho3D-Blender/issues/2 .

[Mike3D]

It's better to have some intensive tests done before merging it to the main repo. That's why I did it that way. Once everything gets OK, I'll send a regular pull request after a thorough clean-up. Also I'd like to fine-tune the available options and features based on feedback.

Feature #2 is mandatory when we are merging all the objects together, but it doesn't make sense when we are exporting separate objects. For versatility purpose, we need the ability to:

• weight when merging, to speed up TESTING
• hide all the objects parented to a single bone, export them separately and parent them to their bones in the Editor (after having exported the skinned object). This is the accurate option to use for a DEFINITIVE export

That's why I've fine-tuned #2.

Basically we need to go as fast as possible when prototyping, and to be the most accurate when exporting the definitive objects. Both objectives might require fine-tuning the exporter if we don't want to impose rigid practices in blender (for example we could solve the issue by doing the weighting in blender and unparent/remove weight when needed).

If you think that some features can already be merged, let me know, I'll send a clean pull-request for them.

[Mike3D]

Everything cleaned-up, some bug fixes for tangents and scene prefabs, some code refactoring and updated to latest revision.

[reattiva]

I've added a branch 'features'. Some notes and questions:

• the node exporting code is now is a separate file;
• 'prefab' does not seem from Urho3D nomenclature, maybe 'nodes' is better;
• kept the plain text writer, why have you switched to the binary writer ? does the editor crash using the plain text write ?
• kept the tangent even if there are no normal maps, you are 90% correct, but tangents can be used for more than bump maps, and there is an option to toggle it off;
• I'll add an option (or a flag _SKIN in the name) to force 100% weights for meshes which have a bone as parent, it does not seem right to link it to the merge option;
• in 'UrhoExportScene' are or will be the dict 'a' and the counter 'm' necessary ? Using explicit names as done in 'IndividualPrefabXml' is much more clean.

[Mike3D]

• 'prefab' does not seem from Urho3D nomenclature, maybe 'nodes' is better; Yes, 'prefab' comes from Unity terminology, Urho uses 'node' and 'scene'. But as 'node' is a too generic word and 'prefab' is referenced many times in Urho3D documentation (check Reference.dox), I've prefered to use 'prefab'.
• kept the plain text writer, why have you switched to the binary writer ? does the editor crash using the plain text write ? I was expecting file size gains and exporting later to full binary, but for now it doesn't work
• kept the tangent even if there are no normal maps, you are 90% correct, but tangents can be used for more than bump maps, and there is an option to toggle it off; When you export many objects at the same time, you can't selectively toggle tangents on/off, that's why I needed this option. Can you please tell me other uses of tangents ?
• I'll add an option (or a flag _SKIN in the name) to force 100% weights for meshes which have a bone as parent, it does not seem right to link it to the merge option; I've chosen the merge option because it fits my workflow and doesn't require an extra option. But I understand that it may be too rigid for other users.
• in 'UrhoExportScene' are or will be the dict 'a' and the counter 'm' necessary ? Using explicit names as done in 'IndividualPrefabXml' is much more clean. I've used this dict to dynamically create elements. In IndividualPrefabXml elements are frozen (always the same). I'm sure there are much better ways to achieve this, but for now this is beyond my skills/knowledge.

[Mike3D]

I think we can close this issue as almost everything has been merged into the Master branch.

[reattiva]

Hello @Mike3D, about the dictionary in UrhoExportScene, maybe I'm missing something big but I really don't see the problem, I've done a test here: https://github.com/reattiva/Urho3D-Blender/blob/nodict/io_mesh_urho/export_scene.py I've done it quickly and the names have to be checked, but it seems good to me, what I am missing?

[Mike3D]

I think that at the begining I misunderstood Urho node hierarchy, which led me to rely on this solution. I'll check your file in-depth and do some tests, I'm pretty sure I have over-complicated things (as usual).

[Mike3D]

Hi reattiva,

Did you find a way to deal with the parent-child hierarchy? Currently it is left as-is with the dict and I don't find a good solution for it.

[Mike3D]

Hi reattiva,

I've started implementing new features: 1) full physics support inside Blender (https://github.com/Mike3D/Urho3D-Blender/blob/master/io_mesh_urho/Physics.jpg) and an option in the Export panel to either use these individual settings or apply settings from the active object to every objects (kind of batch) 2) techniques support (ability to set shader parameters in Blender by appending a flag to the material name and using custom settings set in the Material panel) 3) add other settings like zone and lighting parameters 4) create a button to launch the prefabs in the Editor ...

My goal is to almost skip the need for Urho Editor.

And now that files are nicely separated and we have full access to data for the prefabs, these features are easy to add.

If you find this worthless or off topic, let me know and I won't bother you anymore with these features. I'm also open to other suggestions and insights.

[reattiva]

Hi Mike, it is not worthless for sure. I have some time to write down some thoughts, here they come.

First, let me reply to your old question about the tangent export. Tangent space is a coordinate system, instead Normal map is only a rendering technique, so from my personal point of view, tangent space is much more important and I don't like to link them together. The other big problem when linking them is that you force an user to use the Blender material system, he could only want to generate the geometry and doing the material and textures in other tools (like the Urho editor). For an example on when you use tangent, I really don't know, maybe some water+foam effect on the border of a river. Another stupid example: bump map and normal map, in bump maps you use on a channel of an image, in normal map you use RGB channels to get a vector. So for bump map I need a different tecnique, but if tangent space is linked to normal map, I'm forced to configure it. Probably in Blender bump and normal map are done with the same settings, so it is not a good example, but I hope you get my idea: don't force unnecessary rules on the user. You said that you wanted an individual option per object, this is a good idea, I also thought about it and I think it can be done but it was too much work for me (see later).

This is only my point of view of the exporter. Initially I've written it to export geometry, skeletons and animations with an object per file in mind. This was my objective, it was and it is what I have the strength and time to support. Later, the material export was added, it was not too much of work and with the new Blender paint features it made sense. When it was suggested to insert the scene export I refused because I knew it was too much work for me, moreover, as you have seen, the structure of the exporter was not good enough (a side note: this was my first Blender addon and my first Python program; in my opinion Python is good for little programs, but for bigger works I prefer some more strict language, like C; Python likes unit testing which does not work well with "sorry, no time").

It seems you are very dedicated to this exporter. I really appreciated it. You are working hard on the scene exporter, but as I said I have to leave it to you. I'll try to do some support but don't expect much, sorry. Maybe your idea for this exporter is more useful and much bigger than mine. I can only hinder you and I don't want it, so in this case you have to build it on your fork, if it works good then I'll be glad to trash this one. Be sure that if you can support the scene exporter and you want to work on this repository, I'll be glad and if you want I'll add you as a contributor (to push commits directly). Ok, that's it, I hope it makes sense.

---

About the parent-child hierarchy.

This is new to me, was something that was working but I've removed ? I guess you want to replicate the parent-child hierarchy of Blender in the Urho scene nodes. In this csae you can do this (probably, not tested):

• in the UrhoSceneModel class add a list of UrhoSceneModel children called 'childrenList'
• scan all the models of the scene to populate 'childrenList', you can do this at the end of UrhoScene.Load or at the start of UrhoExportScene:

# Clear the children (not necessary)
for uSceneModel in uScene.modelsList:
    uSceneModel.childrenList.clear()
# Populate
for uSceneModel in uScene.modelsList:
    if uSceneModel.parentObjectName:
        parentFound = False
        # Scan the list again in search of the parent
        for parent in uScene.modelsList:
            if parent.objectName == uSceneModel.parentObjectName:
                parentFound = True
                # Add this model as a child of the parent 
                # (better use a set for childrenList)
                if uSceneModel not in parent.childrenList:
                    parent.childrenList.append(usceneModel)
                break;
        # If the parent is not in the list remove it from the model
        if not parentFound:
            uSceneModel.parentObjectName = None

• scan all the models recursively to recreate the same hierarchy with Urho nodes:

def Traverse(model, parent):
    # Here add a node for model

    # Continue with children
    for child in childrenList:
        Traverse(child, model)
for uSceneModel in uScene.modelsList:
    # Only objects with no parents
    if usm.parentObjectName is None:
        Traverse(uSceneModel, None):

---

About the individual option per object.

This is my idea if you want to give it a try. It is very simple: use a different TOptions class for every object.

• take the current two panels of the exporter's settings, move some of the options in a third panel (for example: "select error", "merge" ...), then move these two panels from the Render page to the Object page in this manner we have two panels with all the options for each object (as you probably have alreayd seen in the Object page there is a "Custom properties" section so it should be doable), we can also leave them in the Render page for the "global options"
• now we have to move the code in init where the options are copied from 'settings' to 'tOption' inside the function Scan, here we will get the 'settings' option for each object copy them to a TOptions object and then we can start the decomposing;
• finally you can add some good user helpers: "a copy settings to other object" button, a "use the global settings" button, etc.

After a lot of good work, and yes! You should be able to remove the tangent generation individually for each object.

[Mike3D]

Hi reattiva,

Thanks for detailed explanations. It is important for me to have your insights. And as time is precious, I don't want to make you loose yours.

For tangents, I got it to work, although I haven't created the option yet.

I don't think pushing commits directly is a good idea as my code needs supervision by a pro. I prefer to push to my fork, drop you a notification about the changes and let you comment, select and decide.

---

About the parent-child hierarchy.

Your current solution for preserving parent-child hierarchy works perfectly (there is no need to do the same procedure as with bones). I was refering to the nodict branch. The dict has been removed everywhere except when we parent a child to its parent node instead of to the root node (line 382 of export_scene.py).

---

About the individual option per object.

Thanks for detailed steps, I'll keep this for later, for now I think it's only useful for a couple of settings, but it may evolve.

---

Cheers

[Mike3D]

Hi reattiva,

I've pushed my latest modifications to https://github.com/Mike3D/Urho3D-Blender

Summary:

• Dropped use of BGE settings, too different from Urho
• Added full customization for components (Static/AnimatedModel, RigidBody and CollisionShape). Accessible in Properties > Object > 'Urho3D ~ Components'
• Added an example of using Material properties to set Vegetation shader parameters (see Properties > Material > 'Urho3D ~ Techniques')
• Added optional skybox when exporting 'scene' prefab
• Added an option to propagate/batch (at export) the Object settings from the active object for every objects (so you just need to set them once for all)
• Added file browser for 'Global Physics' instead of relying on a hard-coded 'Physics.mdl' file
• Removed the 'a' dict as much as possible
• Various minor modifications

Some settings may appear over-tweaked, I personaly like to have full control and put the maximum tasks on auto-pilot.

[Mike3D]

Last modifications:

• Added a new parameter to UrhoExportScene() function to enable multi-pass (one pass for individual and one pass for collective/scene). This allows to remove the IndividualPrefabXml() function and redundant code
• Modified the "Global Physics" behavior: it is now parented to active object node and inherits physics settings from it, except CollisionShape (TriangleMesh is enforced as this function is designed to not overwhelm Bullet when exporting big static (mass=0) geometries).

[Mike3D]

Last modifications:

• Refactored shader parameters to make it versatile
• Bug fixes

[reattiva]

Hi Mike, the user interface for Object and Materials seems massive, maybe it should be moved in a new file. Now it is still good, but if it needs to grow better move it.

[Mike3D]

Hi reattiva,

Thanks for reply.

Yes, I also though of moving almost everything related to prefabs (both UI and xml content) to a new file (or even 2 files depending on final number of lines) to:

• keep files managable (not too big)
• separate asset exporter and prefabs as much as possible

I'll try do this today and push some bug fixes either. Then I'll do some real-life tests for a couple of days to check if everything is OK.

[Mike3D]

Hi reattiva,

I've updated documentation, added missing option to selectively toggle physics, and added support for 'instances', which allows to replicate full Blender scene in Urho.

Concept:

• check for visible empties with a dupli_group
• get visible objects belonging to these empties
• create a copy of the corresponding uSceneModel object
• 'transfer' loc/rot/scale from the Empty to the copy
• append copy to modelsList
• then apply loc/rot/scale to the xml node

It works fine, however I'm stuck at getting orientation (tOptions.orientation) to work. Urho models are already rotated and scaled (position and rotation=(0,0,0), scale =(1,1,1)), while loc/rot/scale for the empties are retrieved before scaling and orientation transform.

I've put an example file (based on GameKit sample), would be great if you could have a look and/or point me in the right direction.

[reattiva]

Ok, give me some time.

[Mike3D]

Many thanks, no need to rush.

[reattiva]

Mike, I give it a look.

• A suggestion: avoid using _rotationeuler and _rotationquaternion here for example, don't ask me why but their are linked to _rotationmode which is the rotation type selected in the Transform panel. It is better to use _matrixlocal or _matrixworld. However maybe they have fixed it in the new versions, try this: random rotate an object in "XYZ euler" mode then print the obj.rotation_quaternion, if it is 1,0,0,0 they have not fixed it.
• For testing the Mono example is good, but for debugging a problem and for me to look for the problem it is too big. A couple of bridges was enough for replicating the problem.
• The problem was that: a crates pile was incorrectly rotated, right?
• The problem here is that Blender use the right hand convetion, Urho use the left hand. To convert them you should do something like this.
• First you apply the "front view" rotation, then you convert to the left hand convention

[reattiva]

Scratch that link, I just remembered bones have different axes than objects axes. It should be: if in Blender you have a translation t=[x,y,z] and a rotation quaternion q=[w,x,y,z], then in Urho they should be t'=[x, z, y] and q'=[w, -x, -z, -y].

[Mike3D]

Many thanks for insights reattiva, I'll try this today.

[Mike3D]

Awesome! rotation_euler was the culprit, works perfectly with matrix_local.to_euler(). A big thank.