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The Blend object allows various effects such as blended inputs, animating the parents of objects, sequencing, partial transformation inheritance, three-point orientation, and other effects. It gives you some extra flexibility in setting up parent-child relationships. It operates like the Switch and Sequence blend sops insofar as it takes more than one input and blends or switches those into one output.
Some potential uses of the Blend op are to animate parenting, such as when one character passes an item to another, or to pass on only part of a parents characteristics.
The Blend Object gives you some extra flexibility in setting up parent-child relationships. It operates like the Switch and Sequence blend sops insofar as it takes more than one input and blends or switches those into one output. As with the other objects, such as lights and cameras, the Blend OP can be placed and wired into networks, but its only purpose is to channel data rather than hold it.
Blend allows for a great deal of control over how much influence each of the inputs has over the child object. This can be set either using a weight value for the input or by masking the input to restrict its effect by channels. Each input has its own set of weight and mask controls. There is a special case when you have exactly three inputs which enables the Normal Offset and Orient Axes parameters. The Offset works by moving the child perpendicular to the plane formed by the three inputs; the Orient function rotates the child such that the first input determines the axes center, the second the +X orientation, and the third the +Y orientation.
The Sequence type simply switches between inputs, so the weight and mask controls become inactive. A Sequence value of 0 parents the child to the first input object, a value of 1 parents it to the next, etc. Any value outside the range of inputs will unparent the child.
Method in which parent transforms are combined to produce a unique transform.
Use Rest Angles
If enabled, this is used when performing shortest path rotation blending to control when flipping will occur. The flipping point will occur when the input orientations differ from the rest angles by more than 180 degrees.
This controls the type of rotation blending used. When blending between full rotations (ie. rx, ry, and rz) at the same time, then in addition to Euler, the Shortest Path rotation blending methods are also available.
Blends each of the rotation components independently.
Shortest Path (Linear)
Use the shortest path when blending rotations between two inputs, with a constant rate of rotation. All 3 rotations (RX, RY, RZ) must be enabled for this option and can only be used when given two inputs.
Shortest Path (Fast Linear)
Use the shortest path when blending rotations between any number of inputs by trading off a constant rate of rotation. All 3 rotations (RX, RY, RZ) must be enabled for this option.
These weights are used to weight each corresponding input parent.
These masks are used to select which component of each parent is used in the blending process.
Rest Angle 1
The world space (euler) rotation values for the
Use Rest Angles option.
Rest Angle Order 1
The rotation order for the corresponding
Rest Angle values.
When exactly three parents are input, the child position may be offset in the direction perpendicular to the triangular plane they form.
When exactly three parents are input this option will orient the child’s local axes to match the orientation of the parents as follows:
When the Type is set to Sequence, this value controls which input parent contributes to the child’s position. It can be used to animate a child from one parent to another. A sequence outside the range of inputs is interpreted as unparenting the child.
Shortest Path Rotation Blending
Use the shortest path possible when blending rotations between two inputs.
Ignore Scales From Inputs
Remove the scales from the input transforms before blending.
When the Type is set to Constrain, this is similar in operation except no 'popping' occurs when transferring from one parent to another.
Since this behavior is state-dependent this value allows the child to reset itself (ie. zero any accumulated transform) at the frame.
The left menu chooses the order in which transforms are applied (for example, scale, then rotate, then translate). This can change the position and orientation of the object, in the same way that going a block and turning east takes you to a different place than turning east and then going a block.
The right menu chooses the order in which to rotate around the X, Y, and Z axes. Certain orders can make character joint transforms easier to use, depending on the character.
Translation along XYZ axes.
Degrees rotation about XYZ axes.
Non-uniform scaling about XYZ axes.
Local origin of the object. See also setting the pivot point .
Scale the object uniformly along all three axes.
This menu contains options for manipulating the pre-transform values. The pre-transform is an internal transform that is applied prior to the regular transform parameters. This allows you to change the frame of reference for the translate, rotate, scale parameter values below without changing the overall transform.
This reverts the translate, rotate, scale parameters to their default values while maintaining the same overall transform.
This sets the translate parameter to (0, 0, 0) while maintaining the same overall transform.
This sets the rotate parameter to (0, 0, 0) while maintaining the same overall transform.
This sets the scale parameter to (1, 1, 1) while maintaining the same overall transform.
This removes the pre-transform by setting the translate, rotate, and scale parameters in order to maintain the same overall transform. Note that if there were shears in the pre-transform, it can not be completely removed.
This completely removes the pre-transform without changing any parameters. This will change the overall transform of the object if there are any non-default values in the translate, rotate, and scale parameters.
Keep Position When Parenting
When the object is re-parented, maintain its current world position by changing the object’s transform parameters.
When the object is being transformed, maintain the current world transforms of its children by changing their transform parameters.
Enable Constraints Network on the object.
Path to a CHOP Constraints Network. See also creating constraints.
You can you use the Constraints drop down button to activate one of the Constraints Shelf Tool. If you do so, the first pick session is filled automatically by nodes selected in the parameter panel.
Set Wireframe Color
Use the specified wireframe color
The display color of the object
Viewport Selecting Enabled
Object is capable of being picked in the viewport.
Script to run when the object is picked in the viewport. See select scripts .
Cache Object Transform
Caches object transforms once Houdini calculates them. This is especially useful for objects whose world space position is expensive to calculate (such as Sticky objects), and objects at the end of long parenting chains (such as Bones). This option is turned on by default for Sticky and Bone objects.
See the OBJ Caching section of the Houdini Preferences window for how to control the size of the object transform cache.
The following examples include this node.