View playback sample source code.

Description

Loads a skeleton and an animation from ozz binary archives. This animation is then played-back and applied to the skeleton. Animation time and playback speed can be tweaked.

Concept

This sample loads ozz binary archive file, a skeleton and an animation. Ozz binary files can be produced with ozz command line tool fbx2ozz, or with ozz serializer (ozz::io::OArchive) from your own application/converter. At every frame the animation is sampled with ozz::animation::SamplingJob. Sampling local-space output is then converted to model-space matrices for rendering using ozz::animation::LocalToModelJob.

Sample usage

Some parameters can be tuned from sample UI:

• Play/pause animation.
• Fix animation time.
• Set playback speed, which can be negative to go backward.

Implementation

1. Load animation and skeleton. Loading from file is covered in detail in the howto section.
   1. Open a ozz::io::OArchive object with a valid ozz::io::Stream as argument. The stream can be a ozz::io::File, or your custom io read capable object that inherits from ozz::io::Stream.
   2. Check that the stream stores the expected object type using ozz::io::OArchive::TestTag() function. Object type is specified as a template argument.
   3. Deserialize the object with >> operator.
2. Allocates runtime buffers (local-space transforms of type ozz::math::SoaTransform, model-space matrices of type ozz::math::Float4x4) with the number of elements required for your skeleton. Note that local-space transform are Soa objects, meaning that 1 ozz::math::SoaTransform can store multiple (4) joints.
3. Allocates sampling cache (ozz::animation::SamplingJob::Context) with the number of joints required for your animation. This cache is used to store sampling local data as well as optimizing key-frame lookup while reading animation forward.
4. Sample animation to get local-space transformations using ozz::animation::SamplingJob. This job takes as input the animation, the cache and a time at which the animation should be sampled. Output is the local-space transformation array.
5. Convert local-space transformations to model-space matrices using ozz::animation::LocalToModelJob. It takes as input the skeleton (to know about joint’s hierarchy) and local-space transforms. Output is model-space matrices array.
6. Model-space matrices array can then be used for rendering (to skin a mesh) or updating the scene graph.