Separate Armature from Animation

[devshgraphicsprogramming]

CFinalBoneHierarchy right now unifies two aspects of skinned animation which can be quite orthogonal to each other, the armature and the animation keyframes.

It would be good to split CFinalBoneHierarchy into asset::IArmature and asset::IAnimationKeyframes, naturally the keyframes would need to refer to an armature (same keyframes don't make sense with different armature).

[devshgraphicsprogramming]

Refer to the glTF overview
https://raw.githubusercontent.com/KhronosGroup/glTF/master/specification/2.0/figures/gltfOverview-2.0.0a.png

Armature (Skelet) is refered to as Skin, and Animation are the keyframes.

[devshgraphicsprogramming]

We should probably add a asset::IArmatureMap that would map one armature onto another as a kind-of "animation adapter" (i.e. mapping from a skeleton with finger bones to a skeleton without fingers).

[devshgraphicsprogramming]

We need to think about the animation keyframe data layout in memory due to #97

[devshgraphicsprogramming]

CFinalBoneHierarchy has a circular dependency on ICPUSkinnedMesh mostly due to joint and keyframe struct definitions.

[devshgraphicsprogramming]

Armatures need bones with global UUIDs and keyframes can be separate per-bone.

template<class BufferType>
class IAnimationKeyframes
{
   public:
      struct alignas(4) AnimationData
      {
         uint32_t keyframeCount;
         uint32_t reserved; // the `keyframe.offset` should be here in the IGPUAnimationKeyframes
         float timestamps[1]; // actually an unbounded array
      };
      struct alignas(4) Keyframe
      {
         uint16_t rotation[3]; // in EF_R16G16B16_SNORM (yes I know format does not exist)
         uint16_t scale[3]; // in EF_R16G16B16_SFLOAT (yes I know format does not exist)
         float translation[3];
      };
   private:
      SBufferOffset<BufferType> animationdata;
      SBufferOffset<BufferType> keyframes;
};

class ICPUAnimationKeyframes : public IAnimationKeyframes<ICPUBuffer>
{
};
class IGPUAnimationKeyframes : public asset::IAnimationKeyframes<IGPUBuffer>
{
};

Then IGPUAnimationKeyframes::animationdata.offset can be used as a UUID for the input per object/node/instance data as outlined in #303

The asset::IArmature and asset::IArmatureMap objects are still to be determined.

[devshgraphicsprogramming]

Figured out how to do it and allow for blends