Animation Blending

As a developer or designer using Qt Quick 3D, I want to be able to blend and interpolate multiple 3D animations together, so that I can create smooth transitions between different animations and achieve more realistic character movements. Specifically, I want to be able to import models with rigged/skinned animations, and be able to play back multiple animations simultaneously, with the ability to blend and interpolate them together in real-time. For example, I may want to blend a walk animation and a run animation to achieve a smooth transition between the two. This will allow me to create more complex and engaging 3D scenes with more realistic and dynamic characters.

Currently Qt Quick 3D only supports a single input pose (animation) for every output pose.  We should be able to accept multiple input poses and provide an API to define programatically how they are blended to become the output pose. Consider the following example model of a character animation:

[Animation Timeline 0 - 135]

Idle [frame 5 - 35]

Walking [frame 40 - 70

Running [frame 75 - 105]

Jumping [frame 110-140]

There is a single Animation timeline provided by the designer for the character model with different poses.  The animation is baked at 30 frames per second, so each sub animation is a 1 second slice of "Animation Timeline 0" and each is designed to loop cleanly.  So if you were to play frames 40 - 70 on repeat you would see the character walking.

I should be able to play more than one animation at a time such that:

frames [40 - 70]  and frames [75 - 105] should be playing but the contribution of each should be configurable.  So say if I wanted to be half walking, half running it each each would only contribute 50% weights to the overall transformation of the skinned animation.