Interpolation can be performed with one or more of the following options:
D3DRMINTERPOLATION_CLOSED
D3DRMINTERPOLATION_LINEAR
D3DRMINTERPOLATION_NEAREST
D3DRMINTERPOLATION_OPEN
D3DRMINTERPOLATION_SLERPNORMALS
D3DRMINTERPOLATION_SPLINE
D3DRMINTERPOLATION_VERTEXCOLOR
If the interpolator is executed CLOSED, the interpolation is cyclic. The keys effectively repeat infinitely with a period equal to the index span. For compatibility with animations, any key with an index equal to the end of the span is ignored.
If the interpolation is OPEN, the first and last keys of each key chain fix the interpolated values outside of the index span.
The NEAREST, LINEAR, and SPLINE options specify how in-betweening is performed on each key chain. If NEAREST is specified the nearest key value is used. LINEAR performs linear interpolation between the 2 nearest keys. SPLINE uses a B-spline blending function on the 4 nearest keys.
The following two options affect only the interpolation of IDirect3DRMMesh::SetVertices:
·VERTEXCOLOR specifies that vertex colors should be interpolated.
·SLERPNORMALS specifies that vertex normals should be spherically interpolated (not currently implemented).