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Revision as of 16:51, 30 March 2011 by Dsventura (talk | contribs) (added known issues)
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Name: Dan Ventura

IRC name: danman


GAM670 Team: GAM670 Slap Your Grandma


GitHub Repository: DanVentura@github


Firefox Build

Building Firefox 4 - Minefield



946-Converting Char to String



127-Make it easier to specify subtitles


Note: this bug is invalid, however I created subtitle unit tests in the process. (popcorn.subtitle.unit.js and popcorn.subtitle.unit.html)

305-Create Unit tests for subtitle plugin




321-Create plugins/index.html


331-Create a Facebook plugin


GAM670 - XAnimation

Source Code


Animation in DirectX9 can be done using .X files. The .X extension refers to a file containing a Microsoft proprietary format for exported 3D models. This format is similar to COLLADA, except the file parsing is handled by DirectX internally. To export a model in .X format in 3Ds MAX, I used a plugin from PandaSoft called the Panda DirectX Max exporter (link on last page).

Once exported, the file contains information each object and maintains their hierarchical relationships between each object. Each object has a frame container and a mesh container. The frame contains information for positioning, while the mesh contains mesh related information such as: bones, textures, etc. To perform skeletal information, the frames must be arranged in an inheritance hierarchy so that the frame's matrix transformations would be relative to it's parent, respectively (Figure 1).


(*Source -

Figure 1: Inheritance hierarchy consisting of a body and two arms. (“Left Arm Frame” would be a shoulder or joint. The name in this diagram may be misleading)

This hierarchy would be established in 3Ds MAX through linking. For more information on how to use bones and make skeletal animations in 3Ds MAX, refer to the references.

In order to properly load this information, we first need to do a little inheritance of some structs to make our lives easier (refer to MeshStructs.h). We need to extend D3DXMESHCONTAINER and D3DXFRAME with some extra data so we can support skinning. Basically, skinning is a technique where you combine the frame (bone) and mesh (skin) matrices so that the mesh's vertex positions will be altered depending on the frame's movement; making the mesh stretch and contract like actual skin. For more information on skinning, refer to the “X File Hierarchy Loading” link in references.

Once we have extended the structures, we have to implement the ID3DXAllocateHierarchy interface to support the extra information we've put into these structures and load the file properly. These functions are called internally as the D3DXloadMeshHierarchyFromX function parses the .X file. (refer to MeshHierarchy.h)

To put all of this into the framework, we create an XObject class which is derived from Object. This will hold model information as well as the animation controller. It will also hold information that allows us to change animation sets and the speed of the animation. (refer to XObject.h)

Animation Controller

To give you an overview of the animation controller and it's functions, here's a list of functions used in this example (descriptions from


// Takes the filename and extracts the information from the x file. memoryAllocator is the

// frame hierarchy, frameRoot is the parent frame, and m_animController is the COM object

D3DXLoadMeshHierarchyFromX(filename, D3DXMESH_MANAGED, d3dd, &memoryAllocator, NULL, &m_frameRoot, &m_animController);

// Like any COM object, you must release it when you're done


// Returns how many different animations are stored in the file


// Advances the animation timeline

m_animController->AdvanceTime(elapsedTime, NULL);


m_animController->GetAnimationSet(m_currentAnimationSet, &set );

// This method sets the animation set to the specified track for mixing. The animation set for

// each track is blended according to the track weight and speed when AdvanceTime is called

m_animController->SetTrackAnimationSet( newTrack, set );

// Removes events from the animation track

m_animController->UnkeyAllTrackEvents( m_currentTrack );

// Enables or disables an animation track

m_animController->KeyTrackEnable( m_currentTrack, FALSE, startTime );

// Sets the rate of play of an animation track

m_animController->KeyTrackSpeed( m_currentTrack, newSpeed, m_currentTime, duration, D3DXTRANSITION_LINEAR );

// Changes the weight of an animation track. The weight is used as a multiplier when combining

// multiple tracks together

m_animController->KeyTrackWeight( m_currentTrack, newWeight, m_currentTime, duration, D3DXTRANSITION_LINEAR );

// Enables or disables a track in the animation controller

m_animController->SetTrackEnable( newTrack, TRUE );

Known Issues

CreateFrame() and CreateMeshContainer

In both CreateFrame and CreateMeshContainer, name was never set in the original code. If you were to implement this code yourself, make sure you set the frame or mesh container's name to the Name parameter. Forgetting to do this will make the animation controller always return NULL from the D3DXLoadMeshHierarchyFromX call.

// for CreateFrame
  newFrame->Name = new char[strlen(Name)+1];
  strcpy(newFrame->Name, Name);
  newFrame->Name[strlen(Name)] = 0;

DestroyFrame() and DestroyMeshContainer()

  delete []meshContainer->Name;


This line used to be in the draw function:

static DWORD lastTime=timeGetTime();

The problem arose when I put multiple instances of XObject in design. Due to the static keyword, this variable would be shared among all of the animated objects. The first animation would run smoothly, while any animations added afterwords would be extremely slow. This is because this variable tells the function when the last time it drew the object's state along the animation time-line, and each object's time-line is different. To fix this, I made last time a data member and initialized it to 0 in the constructor.