FBX® - A Platform-Independent 3D Data Interchange...

FBX® - A Platform-Independent 3D Data Interchange

Technology Cyrille Fauvel - Autodesk

CP4466 - Exchanging 3D data between applications is becoming increasingly important. The FBX exchange technology already facilitates high-fidelity data exchange between several Autodesk® content creation packages, but can be extended to include your proprietary information or be the foundation of complex workflows and save you a lot of time. During this class, we will start with an overview of the capabilities of the SDK and how it can be extended to streamline your workflows. Then we will provide an introduction to using the SDK C++ and Python libraries for plug-in development. To complete the class, we will introduce you to the various FBX tools included with the SDK as well as teaching you ways that FBX can be customized and programmed.

Learning Objectives - At the end of this class, you will be able to:

Explain what FBX is about and its integration in Autodesk products

Be able to decide whether FBX is a solution to your workflow issue

Explain the advantages / inconvenient of using FBX versus a private file format

Create FBX plug-in extension to support your private data in existing pipelines

Connect your application (or pipeline) to FBX

Publish / Import FBX file into your application / (or pipeline)

About the Speaker

Cyrille is a member of the M&E workgroup of the Autodesk Developer Network

(ADN) team, providing developer support, training, and conference presentations on

AutoCAD, RealDWG, Inventor, MapGuide, Maya, and FBX API.

He joined Autodesk in 1994 as an AutoCAD developer based in Switzerland and

California, USA. Later moved to the Developer Support group, and Consulting

division.

Cyrille graduated in Mechanics and Electronics in France, worked as a teacher and C++ developer for a

3rd party developer on AutoCAD. He is fluent in six programming languages, tries to learn Japanese, has

two kids, plays the guitar and trying piano, likes reading, love sailing on oceans, sports, and hand-ball in

particular.

FBX® - A Platform-Independent 3D Data Interchange Technology

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Introduction to Autodesk Developer Network If you are not already an Autodesk Developer Network (ADN) member, and are interested in more

information, please see:

www.autodesk.com/adn - information about ADN

We also post periodically SDK updates and other FBX development information to this location:

www.autodesk.com/developfbx - information about FBX development

Note about Sample Code The sample code that accompanies this course is meant mainly to illustrate the presentation in an easy

to understand the FBX file format and SDK. Because of this, there is minimal error checking and

exception handling. If reusing any of the sample code in your production code, please remember to add

appropriate error handling.

http://www.autodesk.com/adn

http://www.autodesk.com/developfbx


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Contents

Learning Objectives - ............................................................................................................... 1

About the Speaker ..................................................................................................................... 1

Introduction to Autodesk Developer Network ............................................................................. 2

Note about Sample Code ........................................................................................................... 2

Overview .................................................................................................................................... 4

Getting Started Working with FBX .............................................................................................. 4

The Challenges .......................................................................................................................... 5

Challenge 1 – 3D modeling .................................................................................................... 5

AutoCAD tessellation example using the Brep library ......................................................... 6

Inventor tessellation example .............................................................................................10

Challenge 2 – Materials .........................................................................................................13

RealDWG versus FBX ...........................................................................................................14

FBX Extension SDK ..................................................................................................................15

Additional Information & Material ..............................................................................................15

Significant 3rd Parties using FBX ..........................................................................................15

Download the FBX SDK and tools .........................................................................................16

Get Help on FBX ...................................................................................................................16

Feedback ..................................................................................................................................17


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Overview Platform-Independent 3D Data Interchange Technology Autodesk® FBX® asset exchange technology facilitates higher-fidelity data exchange between several Autodesk content creation packages — Autodesk® 3ds Max®, Autodesk® Maya®, Autodesk® MotionBuilder®, Autodesk® Mudbox™, and Autodesk® Softimage® software — and provides support for certain third-party and proprietary applications. Whether you are using FBX within an entertainment pipeline or as part of design production, files are more seamlessly transferred, more data is retained, and workflows are more efficient. FBX was originally designed to be ‘MotionBuilder’ file format, but it actually been expanded to do more. It is now used by many M&E packages to exchange information and share models. For example, when you want to edit a character asset created in Maya into Mudbox, FBX is the foundation for transferring this asset information. FBX is not only a file format; it is also an SDK which is multi-platform. The FBX SDK is available on the 3 major OS (Windows, MacOS & Linux) and come with tools to help you working with asset file.

Getting Started Working with FBX The first thing you need to start integrating FBX into your application or pipeline is, of course, the FBX

SDK. Well, you don’t really need the FBX SDK if you do not intend to programmatically read or write FBX

information in an FBX file. It’s worth pointing out that many 3D applications do support FBX natively and

you can already create FBX file without the SDK itself. For example, Maya, 3ds Max, AutoCAD, Revit from

Autodesk, Unity3d for Unity Studios, and many others, do have import/export FBX functionally.

Something important to note is that the FBX file format is open, and the SDK is free – your application

(or pipeline) can make a free use of that technology and get linked to the rest of the world.

Creating an application that accesses FBX information from inside any application is actually very

straightforward with the Autodesk FBX SDK.

1. Install the latest SDK from http://www.autodesk.com/fbx or www.autodesk.com/developfbx

2. Launch Visual Studio 2005, 2008 or 2010 and create a new project if using C++

3. Include the <fbxsdk.h> header

4. Copy and paste the following code into the main function:

int main (int argc, char **argv) {

KFbxSdkManager *lSdkManager =NULL ;

KFbxScene *lScene =NULL ;

// Prepare the FBX SDK.

InitializeSdkObjects (lSdkManager, lScene) ; // Do something like reading a FBX file or creating a new scene.

// Destroy all objects created by the FBX SDK.

DestroySdkObjects (lSdkManager) ;

http://www.autodesk.com/fbx



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return (0) ;

}

You can also use Python if you are not a fan of C++. In this case:

1. Install the latest Python SDK from http://www.autodesk.com/fbx or

www.autodesk.com/developfbx

2. Copy the fbx.pyd and sip.pyd into your Python site-packages directory

3. Use your favorite Python editor (or notepad)

4. Copy and paste the following code into the main function:

from fbx import * import sys if __name__ == "__main__": # Prepare the FBX SDK. (lSdkManager, lScene) = FbxCommon.InitializeSdkObjects() # Do something like reading a FBX file or creating a new scene. # Destroy all objects created by the FBX SDK. lSdkManager.Destroy() sys.exit(0)

This code (which is identical in both C++ and Python) is the very minimal code you need to use the FBX SDK. It does not do anything yet, but you have all you need to start reading a file or writing a file. We will go into a deeper example later.

The Challenges

Challenge 1 – 3D modeling AutoCAD & Inventor, the 2 major 3D modeler engines from Autodesk for design are using the Autodesk

Shape Manager (ASM). ASM is capable of building manifold, non-manifold 3d geometry as boundary

representation topological model. Their main goal is accuracy and precision. While speed is important

this is a less important criteria than measurement precision. ASM precision for ASM is from 1e-6 to 1e+4

which is very common in mechanical design.

In computer-aided design the constructed design is represented by a boundary representation

topological model, where analytical 3D surfaces and curves, limited to faces and edges constitute a

continuous boundary of a 3D body. Arbitrary 3D bodies are often too complicated to analyze directly. So

they are approximated (tessellated) with a mesh of small, easy-to-analyze pieces of 3D volume —

usually either irregular tetrahedrons, or irregular hexahedrons.




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M&E Autodesk products, such as Maya, 3ds Max, Mudbox & SoftImage, are all using Meshes and Nurbs

(but people mainly use mesh). Measurement is less important than speed and ‘beauty’ (and by beauty I

mean texture, material, artistic deformation of solids, etc…) ASM is that case does not fit well, as being

too rigid for on propose for mechanical design.

Unfortunately, after tessellation, it is not possible to come back. AutoCAD & Inventor will work well with

meshes, so someone may say you can come back, but you would not come back to a boundary

representation of the original solid.

Tessellation techniques are often used to manage datasets of polygons and divide them into suitable

structures for rendering. Normally, at least for real-time rendering, the data is tessellated into triangles,

which are sometimes referred to as triangulation.

AutoCAD tessellation example using the Brep library

Using ObjectARX AcDbObjectPointer<AcDb3dSolid> pSolid (myAsmId, AcDb::kForRead) ;

//- Calculate the approximate size of our solid

AcDbExtents extents ;

pSolid->getGeomExtents (extents) ;

AcGeVector3d v0 =extents.maxPoint () - extents.minPoint () ;

double length =v0.length () ;

AcBrBrep brp ;

brp.set (*((AcDbEntity *)pSolid.object ())) ;

//- Create and set our mesh control object

AcBrMesh2dControl mc ;

//- These settings seem extreme, but only result

//- in ~500 faces for a sphere (during my testing,

//- anyway). Other control settings are available

mc.setMaxNodeSpacing (length / 10000) ;

mc.setMaxSubdivisions (100000000) ;

//- Create a mesh filter object


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AcBrMesh2dFilter mf ;

//- Use it to map our control settings to the Brep

//- VC8:Used const pointer to resolve conversion error

const AcBrEntity *meshEnt =(AcBrEntity *)&brp ;

mf.insert (make_pair (meshEnt, (const AcBrMesh2dControl)mc)) ;

//- Generate a mesh using the filter

AcBrMesh2d m ;

m.generate (mf) ;

//- Extract individual faces from the mesh data

AcBrMesh2dElement2dTraverser it ;

it.setMesh (m) ;

AcGePoint3dArray ptsAll ;

AcGeVector3dArray normalAll ;

while ( !it.done () ) {

AcGePoint3dArray pts ;

AcBrElement2d elt ;

it.getElement (elt) ;

AcGeVector3d normal ;

elt.getNormal (normal) ;

normalAll.append (normal) ;

AcBrElement2dNodeTraverser eltNodeIt ;

eltNodeIt.setElement (it) ;

while ( !eltNodeIt.done () ) {

AcBrNode node ;

eltNodeIt.getNode (node) ;

AcGePoint3d nodePoint ;

node.getPoint (nodePoint) ;

pts.append ((const AcGePoint3d &)nodePoint) ;

eltNodeIt.next () ;

}

//- A face could be a triangle or a quadrilateral

if ( pts.logicalLength () == 4 ) {

//- A quadrilateral face

} else {

//- A triangle face

}

it.next () ;

}

Using .Net

http://through-the-interface.typepad.com/through_the_interface/2011/03/generating-a-mesh-for-

a-3d-solid-using-autocads-brep-api-from-net.html

using Autodesk.AutoCAD.ApplicationServices;

using Autodesk.AutoCAD.BoundaryRepresentation;

using Autodesk.AutoCAD.DatabaseServices;

http://through-the-interface.typepad.com/through_the_interface/2011/03/generating-a-mesh-for-a-3d-solid-using-autocads-brep-api-from-net.html

http://through-the-interface.typepad.com/through_the_interface/2011/03/generating-a-mesh-for-a-3d-solid-using-autocads-brep-api-from-net.html


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using Autodesk.AutoCAD.EditorInput;

using Autodesk.AutoCAD.Geometry;

using Autodesk.AutoCAD.Runtime;

using AcDb = Autodesk.AutoCAD.DatabaseServices;

namespace MeshSolid

{

public class MeshCreator

{

// Mesh a selected solid

[CommandMethod("SOLMESH")]

static public void MeshFromSolid()

{

Document doc =

Application.DocumentManager.MdiActiveDocument;

Database db = doc.Database;

Editor ed = doc.Editor;

// Ask the user to select a solid

PromptEntityOptions peo =

new PromptEntityOptions("Select a 3D solid");

peo.SetRejectMessage("\nA 3D solid must be selected.");

peo.AddAllowedClass(typeof(Solid3d), true);

PromptEntityResult per = ed.GetEntity(peo);

if (per.Status != PromptStatus.OK)

return;

Transaction tr =

db.TransactionManager.StartTransaction();

using (tr)

{

BlockTable bt =

(BlockTable)tr.GetObject(

db.BlockTableId,

OpenMode.ForRead,

false

);

BlockTableRecord btr =

(BlockTableRecord)tr.GetObject(

bt[BlockTableRecord.ModelSpace],

OpenMode.ForWrite,

false

);

Solid3d sol =

tr.GetObject(

per.ObjectId,

OpenMode.ForRead

) as Solid3d;

// Calculate the approximate size of our solid

double length =


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sol.GeometricExtents.MinPoint.GetVectorTo(

sol.GeometricExtents.MaxPoint

).Length;

try

{

using (Brep brp = new Brep(sol))

{

// Create and set our mesh control object

using (Mesh2dControl mc = new Mesh2dControl())

{

// These settings seem extreme, but only result

// in ~500 faces for a sphere (during my testing,

// anyway). Other control settings are available

mc.MaxNodeSpacing = length / 10000;

mc.MaxSubdivisions = 100000000;

// Create a mesh filter object

using (Mesh2dFilter mf = new Mesh2dFilter())

{

// Use it to map our control settings to the Brep

mf.Insert(brp, mc);

// Generate a mesh using the filter

using (Mesh2d m = new Mesh2d(mf))

{

// Extract individual faces from the mesh data

foreach (Element2d e in m.Element2ds)

{

Point3dCollection pts = new Point3dCollection();

foreach (Node n in e.Nodes)

{

pts.Add(n.Point);

n.Dispose();

}

e.Dispose();

// A face could be a triangle or a quadrilateral

// (the Booleans indicate the edge visibility)

AcDb.Face face = null;

if (pts.Count == 3)

face =

new AcDb.Face(

pts[0], pts[1], pts[2],

true, true, true, true

);

else if (pts.Count == 4)

face =

new AcDb.Face(

pts[0], pts[1], pts[2], pts[3],

true, true, true, true

);

// If we have a valid face, add it to the

// database and the transaction

if (face != null)

{


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// Make each face yellow for visibility

face.ColorIndex = 2;

btr.AppendEntity(face);

tr.AddNewlyCreatedDBObject(face, true);

}

}

}

}

}

}

tr.Commit();

}

catch (System.Exception ex)

{

ed.WriteMessage("Exception: {0}", ex.Message);

}

}

}

}

}

Inventor tessellation example Public Sub GenerateFacets()

Dim doc As Document

doc = ThisApplication.ActiveDocument

Dim body As SurfaceBody

body = doc.ComponentDefinition.SurfaceBodies(1)

Dim tolerance As Double

Dim VertexCount As Long

Dim FacetCount As Long

Dim VertexCoords() As Double

Dim normals() As Double

Dim Indices() As Long

tolerance = 0.003

Call body.CalculateFacets(tolerance, VertexCount, FacetCount,

VertexCoords, normals, Indices)

Dim nbTriangles As Long

nbTriangles = 0

Dim i As Integer

For i = 0 To UBound(Indices) Step 3

Dim vIndex1 As Integer



vIndex1 = (Indices(i) - 1) * 3

vIndex2 = (Indices(i + 1) - 1) * 3


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vIndex3 = (Indices(i + 2) - 1) * 3

Dim vertex1(2) As Double



vertex1(0) = VertexCoords(vIndex1)

vertex1(1) = VertexCoords(vIndex1 + 1)








'Call custom method to visualize facet edges

Call DrawLineGraphics(vertex1, vertex2)



nbTriangles = nbTriangles + 1

Next

ThisApplication.ActiveView.Update()

End Sub

Public Sub DrawLineGraphics(ByVal startpt() As Double, ByVal endpt() As

Double)

Dim doc As Document


Dim compDef As ComponentDefinition

compDef = doc.ComponentDefinition

On Error Resume Next

Dim dataSets As GraphicsDataSets

dataSets = doc.GraphicsDataSetsCollection("LineGraphics")

Dim clientGraphics As clientGraphics

clientGraphics = compDef.ClientGraphicsCollection("LineGraphics")

If Err Then

Err.clear()

dataSets = doc.GraphicsDataSetsCollection.Add("LineGraphics")

clientGraphics = compDef.ClientGraphicsCollection.Add("LineGraphics")

Call dataSets.CreateCoordinateSet(1)


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Call clientGraphics.AddNode(1)

Call clientGraphics(1).AddLineGraphics()

End If

On Error GoTo 0

Dim coordSet As GraphicsCoordinateSet

coordSet = dataSets(1)

Dim coords() As Double

Call coordSet.GetCoordinates(coords)

Dim idx As Long

idx = 3 * coordSet.Count

ReDim Preserve coords(0 To idx + 5)

coords(idx) = startpt(0)

coords(idx + 1) = startpt(1)

coords(idx + 2) = startpt(2)

coords(idx + 3) = endpt(0)



Call coordSet.PutCoordinates(coords)

Dim lineGraphics As lineGraphics

lineGraphics = clientGraphics(1).item(1)

lineGraphics.CoordinateSet = coordSet

End Sub

Public Function deleteGraphics(ByVal name As String)

Dim doc As Document


Dim compDef As ComponentDefinition

compDef = doc.ComponentDefinition

On Error Resume Next

Dim dataSets As GraphicsDataSets

dataSets = doc.GraphicsDataSetsCollection(name)

Dim clientGraphics As clientGraphics

clientGraphics = compDef.ClientGraphicsCollection(name)

If Err Then

Exit Function

End If


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On Error GoTo 0

clientGraphics.Delete()

dataSets.Delete()

ThisApplication.ActiveView.Update()

End Function

Challenge 2 – Materials All Autodesk software has been written at different time, but different company which became Autodesk later. Because of this, they all are using a different material library which may create issues when transferring object with material from one application to another. Material properties usually transfer in the FBX file properly, but that does not mean the target application will handle them properly.

Another little issue is that they are also all using different renderer, so even if the material imports well, they may not look exactly the same.

Nowadays, Autodesk applications have a Consistent Material Library, but legacy assets may still be using older definition, so be careful.


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Autodesk workflow

In short DirectConnect’s job is to prepare complex data to be able to be read into a visualization

application. It has 2 parts:

1- The first part is where it tries to keep as rich as possible data model, this is based on ISO10303

and is a standard for moving CAD data around. From there it can process the data either

producing a NURBS or Mesh representation. It does this respecting the topology information of

the CAD original CAD data. It can also produce a stitched model (i.e. add topology) for

unorganized data (Alias Studio). This allows a visualization application to display it without

“cracks”. Importers for original CAD data can easily be written to populate the first data

structure.

2- The second part is a fast access data model that is tuned to supply data to the visualization

application. This is what most applications write an API to, including Showcase and 3ds Max. DC

takes the CAD data and produces data in this form in an .apf file. This supports demand loading,

instances (assemblies). At this point the API can give the user the geometry in a form of a NURB

or a mesh.

RealDWG versus FBX RealDWG is the AutoCAD DWG file format SDK, whereas FBX is also an SDK but does not share the same

file format. They do not really compete as they are addressing different problems. Here is below a quick

comparison of the 2 SDK:


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RealDWG FBX

AutoCAD native file format

ASM ( manifold, non-manifold 3d

geometry )

Accuracy / Precision versus Realistic

Windows only

Not Free

MotionBuilder file format

Mesh, Nurbs

Tessellation

Speed / Rendering versus Precision

Multi-platform

Free

Not Round-trip with ASM

Layered Animation evaluation engine

o Solvers

o PhysX

FBX Extension SDK The FBX Extensions SDK is a set of callback functions that you can define in a dynamically loaded library

(.dll) to customize the behavior of the FBX importing and exporting functionality of 3ds Max, Maya, and

MotionBuilder for example.

The FBX Extensions SDK comes packaged with:

Source code for reading and writing scenes to FBX and Collada files. This source code can be

modified to extend these file formats for your own needs.

Samples to help you read and write in a custom file format.

Source code for sample FBX extensions to 3ds Max, Maya and MotionBuilder.

In short, you do not need to rewrite a complete importer / exporter to customize the FBX file with your

custom data. During an import / export, you can be callback for each FBX node and manipulate the

nodes and/or add your custom information. Unlike the FBX SDK, the FBX Extension SDK is C++ only.

Additional Information & Material

Significant 3rd Parties using FBX EIDOS

Illuminate Labs

Quest3D

Microsoft XNA

SideEffects

Maxon

Luxology

Epic (Unreal)


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Unity

JDA

DigitalExtremes

EuroCom

PixelActive (CityScape)

Goalem

and more…

Download the FBX SDK and tools Visit http://www.autodesk.com/fbx & www.autodesk.com/developfbx

The Autodesk FBX SDK and tools are updated regularly with new features and bugfixes.

Get Help on FBX Forums on Autodesk AREA http://area.autodesk.com/

http://area.autodesk.com/forum/autodesk-fbx/

http://area.autodesk.com/blogs/chris

Support

for FBX plug-ins - [email protected]

for the FBX SDK - [email protected]

Online documentation available and updated regularly here

http://usa.autodesk.com/adsk/servlet/item?siteID=123112&id=16707768

Become an ADN member

http://www.autodesk.com/joinadn



http://area.autodesk.com/

http://area.autodesk.com/forum/autodesk-fbx/

http://area.autodesk.com/blogs/chris

mailto:[email protected]


http://usa.autodesk.com/adsk/servlet/item?siteID=123112&id=16707768

http://www.autodesk.com/joinadn

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Feedback If you have any feedback or questions on FBX or this presentation, please email [email protected].


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