Book Image

Hands-On C++ Game Animation Programming

By : Gabor Szauer
Book Image

Hands-On C++ Game Animation Programming

By: Gabor Szauer

Overview of this book

Animation is one of the most important parts of any game. Modern animation systems work directly with track-driven animation and provide support for advanced techniques such as inverse kinematics (IK), blend trees, and dual quaternion skinning. This book will walk you through everything you need to get an optimized, production-ready animation system up and running, and contains all the code required to build the animation system. You’ll start by learning the basic principles, and then delve into the core topics of animation programming by building a curve-based skinned animation system. You’ll implement different skinning techniques and explore advanced animation topics such as IK, animation blending, dual quaternion skinning, and crowd rendering. The animation system you will build following this book can be easily integrated into your next game development project. The book is intended to be read from start to finish, although each chapter is self-contained and can be read independently as well. By the end of this book, you’ll have implemented a modern animation system and got to grips with optimization concepts and advanced animation techniques.
Table of Contents (17 chapters)

Unit quaternions

Quaternions can be normalized just like vectors. Normalized quaternions represent only a rotation and non-normalized quaternions introduce a skew. In the context of game animation, quaternions should be normalized to avoid adding a skew to the transform.

To normalize a quaternion, divide each component of the quaternion by its length. The resulting quaternion's length will be 1. This can be implemented as follows:

  1. Implement the normalize function in quat.cpp and declare it in quat.h:
    void normalize(quat& q) {
       float lenSq = q.x*q.x + q.y*q.y + q.z*q.z + q.w*q.w;
       if (lenSq < QUAT_EPSILON) { 
       float i_len = 1.0f / sqrtf(lenSq);
       q.x *= i_len;
       q.y *= i_len;
       q.z *= i_len;
       q.w *= i_len;
  2. Implement the normalized function in quat.cpp, and declare it in quat.h:
    quat normalized(const quat& q) {