AnimTestbed/3rdparty/ozz-animation/samples/attach

Ozz-animation sample: Attachment to animated skeleton joints

Description

Demonstrates how to attach an object to an animated skeleton's joint. This feature allows for example to render a sword in the hand of a character. This could also be used to attach an animated skeleton to a joint of an other animated object.

Concept

The idea is to get the joint matrix from the model-space matrices array (for the selected "hand" joint), and use this matrix to build transformation matrix of the attached object (the "sword"). Model-space matrices are outputted by LocalToModelJob. An offset (from the joint) can be applied to the joint transformation by concatenating an offset matrix to joint matrix.

Sample usage

Some parameters can be tuned from sample UI to move the attached object from a join to an other, or change the offset from that joint:

• Select the joint where the object must be attached: "Select joint" slider.
• Offset of the attached object from the joint: "Attachment offset" x/y/z sliders.

Implementation

1. Load animation and skeleton, sample animation to get local-space transformations, optionally blend with other animations, and finally convert local-space transformations to model-space matrices. See Playback sample for more details about these steps.
2. Concatenate object offset transformation (offset relative to the joint) with joint model-space matrix to compute final model-space transformation of the "attached object".
3. Use resulting transformation matrix to render "attached object" or update the scene graph.