At this stage in character development, your model is complete with a mesh, some textures, a skeletal rig, and dummy nodes. What is left is to create individual animation sequences that a game engine will call depending on the player's actions in a game. If you've played some popular 3D games (and I hope you have), you've seen dozens of these sequences, nearly all of which are created manually by an animator or by motion capture. The rest of the animations might be rag-doll effects generated by software such as the Havok physics engine. A typical player character in an FPS can have 50-100 animation sequences.

Also contained within 3ds Max is a fairly powerful animation tool that allows you to key-frame your rig with user-defined footstep patterns in combination with natural physics effects. Key framing is a process whereby you define start and end positions of a basic motion for your character. Then Max fills in the in-between animation frames. For instance, instead of having to create every frame of movement to make a character crouch and stand up, you make two postures (standing and squatting), tell Max the total number of frames, and let it create the rest of the frames. The two postures you create are called key frames, and the process of filling in the frames that Max performs is called tweening.

Max also allows you to import MoCap (motion capture) files that drive your rig and the 3D mesh surrounding it. MoCap is a much better alternative to creating animation sequences because it involves capturing the actual motions of a human actor in a studio and porting them to your character rig. This is an expensive process because it requires a large studio with special image-tracking cameras positioned in three axes. An alternative could be purchasing pre-made MoCap files, but I will show you how to manually create some animations for your character in Chapter 8, "Character Animation in 3ds Max."

Some games like Half-Life 2 incorporate a purchased physics engine, such as Havok, to provide realistic, dynamic character behavior instead of using predefined animations. For instance, if an opponent is killed and falls from a ledge onto other objects, you can see the aforementioned rag-doll effect— the character tumbles like a rag doll, with arms and legs flopping around as they react to being struck. These are animations that the game engine provides on its own instead of calling premade sequences.

You save as files each of the animation sequences you create and name them according to whatever programmers want to call them, such as player_walk or player_jump. Then, when a user presses a certain key or button or uses the joystick in a certain way, the game calls up a particular animation sequence related to that action. After you create all of the animation files, you can package them along with the character mesh, textures, and skeleton and export them from Max to a proprietary game file format using special Max plug-ins that are designed for that game.

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