The curve will be a straight line ending at the right keyframe’s incoming value, and will not match the left keyframe’s incoming value. Unlike the hou.matchout() function, the right keyframe’s incoming value can differ from its outgoing value, so so hou.vmatchout() can produce curves whose right tangent matches the right keyframe but whose right values do not line up.
This function is one of the special animation functions that use the current playbar time and information in the parameter’s keyframes, such as in and out values, tangents, acceleration, etc., to evaluate themselves. Because the information needed to evaluate these functions comes from the keyframes, these functions take few or no parameters.
Calling this function from outside a parameter’s expression will raise a hou.NotAvailable exception.