1. AUTODESK - Media and Entertainment
3ds Max Data Exchange Interface (3DXI)
and COLLADA
Bernard Lefebvre
AUTODESK - Media and Entertainment
Dev. Tech. Support

2. Overview 3DXI – High Level API for 3ds Max SDK
Goals and Targets
Interface Scope Overview
Flexibility and Customization
COLLADA - Digital Asset Exchange Schema
Goals and Guidelines
Library types
3DXI in COLLADA Export plug-in
How things work together
Data round-trip demonstration
Overview

3. 3DXI - High Level API for 3ds Max SDK

4. 3DXI: Goals and Targets
3DXI (formerly known as IGame) was introduced as a set of interfaces for rapid data extraction
Dual target
Allow novice 3ds Max developers to extract data with minimal effort
Allow for the gradual adoption of 3DXI within existing pipelines

5. 3DXI: Goals and Targets
M&E is devoting R&D resources to maintain and expand 3DXI
Short term goal:
Complete the set of entities exposed when parsing the scene graph
Mid term goal:
Incorporate import capabilities to the API
Long term goal:
Become a standard API for data exchange in and out of 3ds Max
Demo the per face examples from the sdk – adding tessellation and viewing the copied data etc..

6. 3DXI: Interface Scope Overview
Provides unified Scene traversal and Object enumeration
Well defined data containers for top level Nodes and Materials interfaces with list of their children
class IGameScene{ virtual bool InitialiseIGame(bool selected = false)=0; };

7. 3DXI: Interface Scope Overview
Built-in Conversion System
Coordinate System Conversions (3ds Max, OpenGL, DirectX, custom)
IGameConversionManager * cm = GetConversionManager();
cm->SetCoordSystem(IGameConversionManager::IGAME_D3D);

8. 3DXI: Interface Scope Overview
Access to 3ds Max elements
Geometry, Spline, Lights and Cameras, Helper Objects
Modifiers, Skin Deformers, Materials, Textures (including Bitmap)
Controllers, Constraints, IK Chain, Bipeds
Object Parameter Containers
Paramblocks, Custom Attributes, MXS plugins, Custom Node Data

9. 3DXI: Interface Scope Overview
Mesh Access
All Vertex Colors, Alpha, Illumination, Normals, Texture Coordinates, Binormals, and Tangents are accessed directly
Vertex normals calculated based on the smoothing group of the face
Support for Mesh and MNMesh (N-sided polygons)

10. 3DXI: Interface Scope Overview
Animation
Access to TCB, Euler Controllers, Constraints and Biped systems
Option for key sampling for parametric controllers

11. 3DXI: Interface Scope Overview
DirectX Effects
DirectX 9 Shader Material supported directly via IGameMaterial

12. 3DXI: Interface Scope Overview
IGameFX – main interface to D3D effect, compliant with HLSL COLLADA FX (1.4.0)
IGameFXProperty – interface for individual parameter (property), can be extracted to general IGameProperty
IGameFXTechnique – interface for technique information
IGameFXPass – interface for pass information
IGameFXFunction – access to function’s data

13. 3DXI: Interface Scope Overview
Graphical Class Hierarchy
IGameScene
IGameConstraint
IGameGenMod
IGameGenObject
IGameNode
IGameMorpher
IGameLight
IGameModifier
IGameControl
IGameSkin
IGameCamera
IGameKey
IGameObject
IGameIKChain
IExportEntity
IGameMaterial
IGameSpline
IGameFX
IGameTexture Map
IGameXRefObject
IGameConversionManager
IGameUVGen
IGameSupportObject
IPropertyContainer
IGameProperty
IGameMesh
FaceEx

14. 3DXI: Interface Scope Overview
Code Example: Simplification
Extracting key frame data from controller (3ds Max SDK):
Control * cont = node->GetTMController()->GetPositionController()
if (!cont)
return;
IKeyControl * ikc = GetKeyControlInterface(cont);
// TCB point3
if (ikc && (cont->ClassID()== Class_ID(TCBINTERP_POINT3_CLASS_ID, 0))) {
for (int i=0; i<ikc->GetNumKeys(); i++) {
ITCBPoint3Key key;
ikc->GetKey(i, &key);
// process data }

15. 3DXI: Interface Scope Overview
Code Example: Simplification
The same data in 3DXI can be extracted as:
IGameKeyTab poskeys;
IGameControl * gameControl = gameNode->GetIGameControl();
if (!gameControl) return;
gameControl->GetTCBKeys(poskeys,IGAME_POS));
// process data

16. 3DXI: Flexibility and Customization
Ability to fit into existing plugins
All the major 3DXI classes provide access to the underlying 3ds Max object:
INode * node = gameNode->GetMaxNode();
Object * obj = gameObject->GetMaxObject();
Mesh * mesh = gameMesh->GetMaxMesh();
Mtl* mat = gameMaterial->GetMaxMaterial();
Conversion from INode* to IGameNode*:
IGameNode * gameNode = GetIGameInterface()->GetIGameNode(node);

17. 3DXI: Flexibility and Customization
Object properties are stored in different containers
IParamBlock, IParamBlock2, Custom Attributes, MXS plugins
3DXI collects all properties from different 3ds Max containers automatically

18. 3DXI: Flexibility and Customization
And provides an interface to extract them by index or by name (as the name known to MAXScript)
IGameObject * obj = gameNode->GetIGameObject();
switch(obj->GetIGameType()){
case IGameObject::IGAME_LIGHT: {
IGameLight * light = (IGameLight*)obj;
IGameProperty * prop =
GetIPropertyContainer()->QueryProperty(_T("color"));
Point3 pvalue;
if (prop) // property can be NULL, if name not found
prop->GetPropertyValue(pvalue); }

19. 3DXI: Flexibility and Customization
If you use User Defined Properties:
XML defined in IGameProp.xml
<ExportUserData>
<UserProperty>
<id>101</id>
<simplename>MyString</simplename>
<keyName>IGameTestString</keyName>
<type>string</type>
</UserProperty></ExportUserData>
Extract Custom Property
IGameObject * obj = gameNode->GetIGameObject();
IGameSupportObject * hO = (IGameSupportObject*)obj;
IPropertyContainer * cc = hO->GetIPropertyContainer();
IGameProperty * prop = cc->QueryProperty(101);
TCHAR * buf;
if(prop)
prop->GetPropertyValue(buf);
We would rather recommend using Custom Attributes.

20. 3DXI: Flexibility and Customization
Example of IGameProperty advantage for lights:
Omni - is paramblock based
Skylight – is paramblock2 based
Mr_Area_Omni – is scripted plugin
A single way to access property:
IGameProperty * prop = cc->QueryProperty(_T(“Multiplier"));

21. COLLADA - Digital Asset Exchange Schema

22. COLLADA: Goals and Guidelines
COLLADA - An open Digital Asset Exchange (XML) Schema for the interactive 3D industry
Driven by Sony Computer Entertainment , Inc.
Current version is 1.4.0
COLLADA ("COLLAborative Design Activity")
open standard for the interactive entertainment industry that defines an XML-based schema for 3D authoring applications to freely exchange digital assets without loss of information. This enables multiple software packages to be combined into extremely powerful tool chains. COLLADA support programmable shaders authored and packaged using OpenGL ES Shading Language so that leading 3D authoring tools can work effectively together to create OpenGL ES applications and assets.

23. COLLADA: Goals and Guidelines
COLLADA is not a game engine format
Goals:
To liberate digital assets from proprietary binary formats into XML open-source format
No binary data within XML Shema
Flexibility and Scalability
To provide a standard common format for digital content users
XML Schema, Specification, and API
To be a basis for common data exchange between 3D applications
User’s quote: “The days of game developers writing custom export plug-ins for modeling packages are, from what we've seen, over”

24. COLLADA 1.4 New features. COLLADA FX COLLADA Physics
Cross-platform standard shader and effects definition written in XML.
Targets:
High-end systems running OpenGL Shading Language (GLSL) and Cg (HLSL coming),
Resource-constrained systems (OpenGL ES 1.x profile).
COLLADA Physics
Rigid Body Dynamics, Rag Dolls, Contraints, Collision Volumes.
Enables data interchange between Ageia (Novodex), Havok, Meqon, ODE and other game physics middleware
Collada FX
Next generation lighting, shading and texturing
High level effects and shaders
Support for all shader models (1.x, 2.0, 3.0) under CG and GLSL profiles.

25. COLLADA: Library types
library_animations, library_animation_clips
library_geometries
library_controllers
library_nodes
library_materials, library_images
library_cameras, library_lights
library_visual_scenes
library_effects
library_physics_models
library_physics_materials, library_force_fields
library_physics_scenes

26. COLLADA: Library types
Example of <animation> created by 3ds Max COLLADA exporter
<animation id="ColladaAnim.max_animation">
<animation id="Box01-Translate">
<source id="Box01-Translate-X-time">
<float_array id="Box01-Translate-X-time-array" count="2"> </float_array>
<technique_common>
<accessor source="#Box01-Translate-X-time-array" count="2">
<param name="TIME" type="float"></param>
</accessor>
</technique_common>
</source>
<source id="Box01-Translate-X-value">
<float_array id="Box01-Translate-X-value-array" count="2"> </float_array>
<accessor source="#Box01-Translate-X-value-array" count="2">
<param name="TRANS.X" type="float"></param>

27. COLLADA: Library types
Example of <animation> (Continue)
<source id="Box01-Translate-X-interp">
<Name_array id="Box01-Translate-X-interp-array" count="2">BEZIER BEZIER</Name_array>
<technique_common>
<accessor source="#Box01-Translate-X-interp-array" count="2"> <param name="TRANS.X" type="Name"></param>
</accessor>
</technique_common>
</source>
<source id="Box01-Translate-X-intgt">
<float_array id="Box01-Translate-X-intgt-array" count="2">-0 -0</float_array>
<accessor source="#Box01-Translate-X-intgt-array" count="2"> <param name="TRANS.X" type="float"></param>
<source id="Box01-Translate-X-outtgt">
<float_array id="Box01-Translate-X-outtgt-array" count="2">0 0</float_array>
<accessor source="#Box01-Translate-X-outtgt-array" count="2">
<param name="TRANS.X" type="float"></param>

28. COLLADA: Library types
Example of <animation> (Continue)
<sampler id="Box01-Translate-X-sampler">
<input semantic="INPUT" source="#Box01-Translate-X-time"></input>
<input semantic="OUTPUT" source="#Box01-Translate-X-value"></input>
<input semantic="INTERPOLATION" source="#Box01-Translate-X-interp"></input>
<input semantic="IN_TANGENT" source="#Box01-Translate-X-intgt"></input>
<input semantic="OUT_TANGENT" source="#Box01-Translate-X-outtgt"></input>
</sampler>
<channel source="#Box01-Translate-X-sampler" target="Box01/Trans.X"></channel>
</animation>

29. COLLADA: Library types
Example of <mesh> element exported by 3ds Max COLLADA exporter
<geometry id="Box01-obj" name="Box01">
<mesh>
<source id="Box01-obj-position">
<float_array id="Box01-obj-position-array" count="24"> </float_array>
<technique_common>
<accessor source="#Box01-obj-position-array" count="8" stride="3">
<param name="X" type="float"></param> <param name="Y" type="float"></param>
<param name="Z" type="float"></param>
</accessor>
</technique_common>
</source>
<source id="Box01-obj-normal">
<float_array id="Box01-obj-normal-array" count="72"> </float_array>
<accessor source="#Box01-obj-normal-array" count="24" stride="3">

30. COLLADA: Library types
Example of <mesh> (Continue)
<source id="Box01-obj-mapchan-1">
<float_array id="Box01-obj-mapchan-1-array" count="36"> </float_array>
<technique_common>
<accessor source="#Box01-obj-mapchan-1-array" count="12" stride="3">
<param name="S" type="float"></param> <param name="T" type="float"></param>
<param name="R" type="float"></param>
</accessor>
</technique_common>
</source>
<vertices id="Box01-obj-vertex">
<input semantic="POSITION" source="#Box01-obj-position"></input>
</vertices>
<polylist material="ColorMaterial_ " count="6">
<input semantic="VERTEX" source="#Box01-obj-vertex" offset="0"></input>
<input semantic="NORMAL" source="#Box01-obj-normal" offset="1"></input>
<input semantic="TEXCOORD" source="#Box01-obj-mapchan-1" offset="2" set="1"></input>
<vcount> </vcount>
<p> </p>
</polylist>
</mesh>
</geometry>
Vcount: nb vertex for each poly

31. COLLADA: external references.
<library_visual_scenes>
<visual_scene id="Animation_max" name="Animation_max">
<node id="MyGeometry" sid="MyGeometry" name="MyGeometry">
<translate sid="Trans"> </translate>
<rotate sid="RotZ"> </rotate>
<rotate sid="RotY"> </rotate>
<rotate sid="RotX"> </rotate>
<instance_geometry url="./SourceGeometry.dae#MyGeometry-obj"> </instance_geometry>
</node>
</visual_scene>
</library_visual_scenes>
Max X-Ref can be exported as external references.
NameOfMaxFile.dae

32. 3DXI in COLLADA Export plug-in

33. 3DXI for COLLADA M&E is fully committed to COLLADA
COLLADA Exporter and Importer effort by Feeling Software, Inc. Personal thanks to Guillaume Laforte
3ds Max Exchange plugins for COLLADA support version 1.4.0
For 3ds Max 7 and
3ds Max 8.

34. 3DXI for COLLADA 3DXI in action
All code snippets are taken from 3ds Max COLLADA exporter
//starting point
int ColladaExporter::DoExport(const TCHAR* name, ExpInterface* ei, Interface* i, BOOL suppressPrompts, DWORD options) {
IGameScene* pIgame = GetIGameInterface();
pIgame->InitialiseIGame(bool(options & SCENE_EXPORT_SELECTED)); }
Entire scene traversal happening here
All root nodes and materials (including their children) are enumerated

35. 3DXI for COLLADA 3DXI in action
All code snippets are taken from 3ds Max COLLADA exporter
//Create <material::effect> Library
IGameMaterial* mat = pIgame->GetRootMaterial(i); //for all scene mtls
IGameFX* gameFX = mat->GetIGameFX();
if(!gameFX) return; //not a DX Material
const TCHAR* fxFilename = gameFX->GetEffectFileName();
int np = gameFX->GetNumberOfProperties();
for (int j = 0; j < np; j++){
IGameFXProperty* fxp = gameFX->GetIGameFXProperty(j);
IGameProperty* property = fxp->GetIGameProperty(); // access to IGameProperty
if (fxp->GetPropertyUsage() == IGameFXProperty::IGAMEFX_LIGHT)
IGameNode* lightNode = fxp->GetBindingNode(); // bound light node }
int nt = gameFX->GetNumberOfTechniques(), i = 0; do {
IGameFXTechnique* fxTechnique = gameFX->GetIGameFXTechnique(i);
for (int j = 0; j < fxTechnique->GetNumberOfPasses(); j++)
IGameFXPass* pass = fxTechnique->GetIGameFXPass(j);
while (++i < nt);

36. 3DXI for COLLADA 3DXI in action
All code snippets are taken from 3ds Max COLLADA exporter
//extract Object data
IGameNode *node = pIgame->GetTopLevelNode(i); //for all scene nodes
IGameObject* object = node->GetIGameObject();
switch (object->GetIGameType()) {
case IGameObject::IGAME_LIGHT: AddLightObject(node, object); break;
case IGameObject::IGAME_CAMERA: AddCameraObject(node, object); break;
case IGameObject::IGAME_MESH: AddMeshObject(node, object); break; }
Object properties are collected into IGamePropertyContainer at this point.

37. 3DXI for COLLADA 3DXI in action – Access Mesh
All code snippets are taken from 3ds Max COLLADA exporter
//export Mesh
IGameObject* object = node->GetIGameObject();
IGameMesh* mesh = (IGameMesh*) obj;
mesh->InitializeData();
// mesh vertex positions
for (int i = 0; i < mesh->GetNumberOfVerts(); i++){
Point3 vert;
mesh->GetVertex(i, vert, exporterOptions->ExportObjectSpace()); }
// mesh normals
for (int i = 0; i < mesh->GetNumberOfNormals(); i++){
Point3 n;
mesh->GetNormal(i,n, exporterOptions->ExportObjectSpace());
// mesh tangents and binormals for a channel
int chan = 1;
for (int i = 0; i < mesh->GetNumberOfTangents() ; i++){
Point3 t,b;
t = mesh->GetTangent(i,chan);
b = mesh->GetBinormal(i,chan);
// mesh texture vertices for a channel
for (int i = 0; i < mesh->GetNumberOfMapVerts(chan); i++){
Point3 tv;
mesh->GetMapVertex(chan, i, tv);
For mesh all data (vertices, normals, map channels, binrormals, etc) collected/calculated. FaceEx* structure is stored per face basis

38. 3DXI for COLLADA Data round-trip demonstration
Mesh model textured, skinned with animated biped as a rig

39. 3DXI Resources On the DVD: http://beta.discreet.com
On the DVD:
3DXIHelp.chm (maxsdk\help)
3DXI Headers (maxsdk\include\IGame)
COLLADA Exporter and Importer (maxsdk\samples\Collada)

40. Questions ?