instance_array_matrix.md

EXT_INSTANCE_ARRAY_MATRIX

Introduces the "arrayMatrix" instance subtype.

Parameters:

Name	Type	Description
group	GROUP	Group to be instanced, required
array.transform	ARRAY1D of FLOAT32_MAT4	Array of transforms, required
array.id	ARRAY1D of UINT32	optional array of ids

For evey matrix in the array.transform array the group is placed in the scene transformed by that matrix.

skeletal_transform.md

EXT_SKELETAL_TRANSFORM

Introduces the "skeletal" instance subtype.

"skeletal" instance Parameters:

Name	Type	Description
group	GROUP	Group to be instanced, required
bone.transform	ARRAY1D of FLOAT32_MAT4	Array of transforms, required
id	UINT32	Object id

Geometries with a vertex.position array parameter additionally have the following parameters

Geometry Parameters:

Name	Type	Description
vertex.boneWeight	ARRAY1D of FLOAT32_VEC4	bone weight
vertex.boneIndex	ARRAY1D of UINT32_VEC4	bone index

If the geometry is instanced by a non-skeletal instance subtype these parameters are not used.

If the geometry is instanced by a skeletal instance subtype the the transform is calculated per vertex as:

transform = boneWeight.x*bone.transform[boneIndex.x]
          + boneWeight.y*bone.transform[boneIndex.y]
          + boneWeight.z*bone.transform[boneIndex.z]
          + boneWeight.w*bone.transform[boneIndex.w]

If a geometry without these parameters is instanced by a skeletal instance subtype vertex.boneWeight and vertex.boneIndex are treated as if they were (0, 0, 0, 1) and will therefore use bone.transform[0] per above formula.