Create an Animated iProp - Tank Tracks

Create an Animated iProp - Tank Tracks

05/05/2011 10:25:25http://developer.reallusion.com/whitepaper/Tank_Tracks/index.htm


Through upgrade of iClone, Reallusion Content Store will support more realistic objects. In earlier content packs, the track movements

are made with UV animation which is visually effective but still looks unreal. In this chapter, we introduce another method to create more

mechanical tracks of a tank. The following videos show a new type of tracks which include lots of moving chains. It has a better visual

effect than using UV animation in the past.

There are five main steps for creating a animated track in 3Ds Max before exporting to iClone.

1. Create chains of track

2. Define a path to roll the chains

3. Setup moving behavior in animation

4. Transform and store animation by FBX

5. Export Props with AML perform

We will also show you how to compile rolling animations and AML in the final stage of this document.

In the following pipeline, we recommend users to build tracks in vertical distribution. After baking animations through FBX conversion, we

will then run tracks from vertical to horizontal. If tracks directly roll on the horizontal path by Spline IK solver, it maybe cause element

mesh overturn randomly.

Create Elements of Track

Let's start to create elements of continuous tracks. Create boxes in a row as shown below, then attach them into a single mesh. Make

sure to give ResetXForm from the Utilities panel and convert this mesh as polygons before skinning bones.


Open Bone Tools panel to Create Bones through each chain.



Apply Skin modifier to the mesh and create bones for each piece of the mesh. To make rigid skinning , each chain must be fully weighted

to each bone, and no vertices of neighboring chain should be included.

Save this 3Ds Max file and name it as "Tank Tracks_Straight.max".

Define a path to roll elements

Draw a Line to follow the moving path. To prevent unpredictable chain overturn after applying Spline IK solver, we recommend you draw

this line in Top or Perspective viewport.



The next step is using Spline IK solver to make the straight tracks roll on the path:

1. Have Bone01 selected.

2. Activate toolbar "Animation" > "IK Solvers" > "SplineIK Solver".

3. After activating SplineIK Solver, you will find a dotted line in-between Bone01 and your mouse. Please pick the end bone

"Bone21" when the dotted line appears.

4. After picking Bone21, the dotted line will appear in-between Bone21 and your mouse. Finally, pick the Line that we drew earlier.

Once the steps are complete, each element of the continuous tracks will snap and follow the path.

After all the pieces snaps it will generate some dummy Points ( wireframe cube )to help you adjust the shape of the path. Adjust Bone01

and Bone21 to the adjacent position by moving the dummy points.



Save current 3Ds Max file and name it as "Tank Tracks_SplineIKsolver.max".

Setup moving behavior in animation

In this section, we would set animation keys to simulate the moving behavior of tracks. Let's begin the follow procedure at the 0 frame.

Select the first bone "Bone01" and go to the "Motion" control panel.

Double-click "Path Constraint" to activate in Position List. It would show another list to set up Path Parameters. % Along Path in

Path Option is the key to animate our tracks, and it's default value is 0.0.



Press "N" on keyboard to activate Auto Key mode.

Go to frame 120, then change % Along Path from 0 to 100. There will be a key mark (red) on the spinner.



Play Animation on play bar. The continuous tracks will roll along the path.

Save present 3Ds Max file and name it as "Tank Tracks_Rolling.max".

Transform and store animation by FBX

Now we are ready to export Model and animation into iClone4. The pipeline is baking animation through collapse of transformation in FBX

because iClone can't translate animated keys of SplineIK solver. You could survey the setting of FBX export and import in Whitepaper "

Creature Base Models".



FBX Export setting



FBX Import setting

There are tracks mesh, bones, splineIK solver, points and animation in the same scene of 3Ds Max. We have to simplify them and just

include mesh, bones and animation.

1. Only select all bones with rolling animation at "Tank Tracks_Rolling.max".

Press "File" > "Export Selected" to save these bones as FBX format "Animation.FBX".

Note: Animation baking function is available in FBX 2009.3 plug-in or later versions, which support 3ds Max R9 or later.



2. Reset a new 3Ds Max file, press "File" > "Import" to load the previous FBX file you exported.

3. Select all bones in this new scene. Press "File" > "Save Animation" to store the animation keys as a XML Animation file

"Animation.xaf"

4. Open the prepared 3Ds Max file "Tank Tracks_Straight.max", then only select all straight bones. Press "File" > "Load

Animation" to input the baking keys from "Animation.xaf", Make sure the "Absolute" and "Replace" check the box.



5. Finally the straight bones and mesh would transform into rolling path by XML animation.

Create an Animated iProp - Tank Tracks

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