blendDevice node

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This node provides reliable motion capture device data monitoring and fast animation preview functionality for motion capture (unclutched) input devices. Its designed role is to service the device attribute attachments, (see attachDeviceAttr command), device data monitoring control (see enableDevice command), and "take" evaluation (see applyTake -preview).

This node blends the three possible value sources for a device attached attribute:

Current device data from the device attachment
applyTake -preview data
Other keyframe or input data from input[0]

The formulaic version of this node:

    pcPrev = blender * input[0] + (1-blender)*previewData(time)
    output = deviceBlend * deviceValue + (1-deviceBlend) * pcPrev

where previewData(time) represents the lookup in data of the current preview value based on time, data, timeStamp, et. al. The previewData value is a linear interpolation at the current time.

In order to support correct unit conversion the input and ouput connections have angular, linear, and unitless versions. Evaluation of an output draws input values only from the input attribute of the matching type. The effect on the node's behavior can be seen by substituting inputLinear and outputLinear or inputAngle and outputAngle in the equations above for input and output, respectively.

Notes:

While each of the inputs is a multi attribute, only the 0th entry is ever considered in evaluating the output value.

Remember that device data is considered to be in internal unit and is not subject to unit conversion. Thus if a rotational device channel is attached to a linear attribute, the rotations in radian will be assigned to the linear unit in cm.

Preview data is not stored in a saved filed.

While this node could possibly be used for other purposes than functioning as the arbiter of various device and animation data, it is not supported for use in any other role.

Node name	Parents	Classification	MFn type	Compatible function sets
blendDevice	blend	math	kBlendDevice	kBase kNamedObject kDependencyNode kBlend kBlendDevice

Attributes (14)

blender, data, deviceBlender, deviceValue, inputAngle, inputLinear, minTime, offset, outputAngle, outputLinear, period, stride, time, timeStamp

Long name (short name) Type Default Flags

time (t) time 0film

The current time value, implicitly connected to the animation time. This attribute is internal, do not connect or set.

deviceValue (dv) double 0.0

The value of the current device state from the device attribute attachment. This attribute is internal, do not connect or set.

deviceBlender (db) float 0.0

Reflects current clutch/enable state of the device. Act as the selector for current device data or animation/preview data. This attribute is internal, do not connect or set.

inputAngle (ia) angle (double) 0.0deg

Available for connection (or connected to) the anim curve for the device attached attribute, if the attribute is angular.

outputAngle (oa) angle (double) 0.0deg

Blended output computed from angle inputs. Typically connected to the device attached attribute.

inputLinear (il) distance (double) 0.0cm

Available for connection (or connected to) the anim curve for the device attached attribute, if the attribute is linear

outputLinear (ol) distance (double) 0.0cm

Blended output computed from linear inputs. Typically connected to the device attached attribute.

blender (b) float 1.0

Controls the source of animation data as either 0.0 (source is data) or 1.0 (source is input[0], inputAngle[0], or inputLinear[0]).

minTime (mnt) double 0.0

Begining of time range for preview data

period (p) double 0.0

If non-zero the preview data is periodic, and this attribute is the period of the preview data, and the timestamp attribute is ignored. If period is set to 0.0, the timestamp attribute is used to provide temporal information for the preview data.

timeStamp (ts) doubleArray empty

Contains the timestamp for preview data (ignored if period is > 0 ) Timestamp values are relative to minTime, and must be > 0 and monotonically increasing.

data (d) doubleArray empty

Contain the preview data values from applyTake -preview

stride (st) integer 1

Is the record size of the preview data array. Combined with offset, allows data to be a 2 dimensional array indexed for a particular column.

offset (off) integer 0

Is the offset into a record in the preview data array for the device preview value for this attribute. Combined with stride, allows data to be a 2 dimensional array indexed for a particular column.