Using Motion Flow Mode to Combine Animations

Motion Flow Mode is used to animate one or more bipeds using a network of clips. The network of clips are joined together by transitions. This network is used to animate one biped or a crowd of bipeds. To animate one biped a single script is created that uses a list of clips to animate the biped. To animate a crowd of bipeds you can either use the random method of clip selection or a delegate driven approach. The random method simply picks clips at random and creates random scripts for each biped. This approach works well if the bipeds are standing still and don't require collision detection, a crowd at a ball game for example. The delegate driven approach also uses a network of clips but instead of random selection it bases clip selection on a delegates speed and heading. The delegate driven approach uses many parameters to simulate moving crowds and incorporates collision detection, surface follow and other parameters. For a detailed breakdown of delegate driven crowd behavior see Crowd Animation.

Motion Flow Mode provides an area to arrange clips into a network and tools to create and edit transitions. Clip and transition percentages are also set using controls in Motion Flow mode. Clip and transition percentages are used by the Create Random Motion command during motion synthesis. In a delegate driven crowd simulation, clips are arranged to follow a logical sequence. For example, the first clip could be a start walk clip, then a walk loop, then a branch to a turn right and turn left clip, then a slow to stop clip and so on. During synthesis this arrangement is used to pick clips. If the software senses a collision ahead, the slow to stop clip is selected, or a veer to avoid clip is chosen.


Transitions link motion files (clips) together to create longer character animation and crowd simulations. Transitions can be created manually with the transition editor or automatically by the software. Optimized transitions use minimum foot sliding rather than the default minimum motion loss. To create optimized transitions use the Optimize Selected Transition on the Motion Flow Graph toolbar or Optimize Transition in the Transition Editor. Optimized transitions take time to calculate but yield high quality transitions.

Crowd simulations can potentially use dozens of motion clips so automatic creation of optimized transitions can be a big time saver. Whether you plan on animating one or many bipeds using Motion Flow mode you'll need transitions between the clips in the Motion Flow Graph.

Random Motion

The Create Random Motion command uses clip and transition percentages to create random scripts to animate one or more bipeds. First you put bipeds into a Shared Motion Flow, and then you select clips and create transitions between the clips. The software then randomly traverses the clips to create random scripts for each biped.

Unified Motion

The Create Unified Motion command allows you to create one motion from a script. The entire unified motion is then available when you exit Motion Flow Mode.

Files and Directories

The location of the referenced .bip files is saved in the .mfe file. If a .bip file cannot be found, the program looks to the motion flow directory specified in \plugcfg\biped.ini. By default, this directory is MoFlowDir=<maxdir>\cstudio\scripts

If a referenced .bip file cannot be found in its current location, you will need to move it to the specified Motion Flow directory. You can change the location of this directory at any time by editing your biped.ini file with a text editor. The new directory will be used the next time you restart 3D Studio MAX. You can also add multiple search paths to your biped.ini file by repeating the MoFloDir= line multiple times. The program will search the directories in the order they appear and will use the first instance of the file that it finds. When network rendering the filenames need to be UNC compatible.

See also