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)

Optimizing texel fetches

Even on a gaming PC, rendering over 200 crowd characters will take more than 4 milliseconds, which is a pretty long time, assuming you have a 16.6 ms frame time. So, why is crowd rendering so expensive?

Every time the GetPose helper function is called, the shader performs 6 texel fetches. Since each vertex is skinned to four influences, that's 24 texel fetches per vertex! Even with a low poly model, that is a lot of texel fetches. Optimizing this shader will boil down to minimizing the number of texel fetches.

The following sections present different strategies you can use to minimize the number of texel fetches per vertex.

Limiting influences

A naive way to optimize texel fetches would be to add a branch to the shader code. After all, if the weight of the matrix is 0, why bother getting the pose? This optimization could be implemented as follows:

    mat4 pose0 = (weights.x < 0.0001)? 
     ...