Bone object

When the object is re-parented, maintain its current world position by changing the object’s transform parameters.

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.

Translation along XYZ axes.

Degrees rotation about XYZ axes.

Scale the object uniformly along all three axes.

Object to point to. Constrains an object so its -Z axis always points at another object’s origin.

When specifying a look at, it is possible to specify an up vector for the look at. This controls the roll of this object when looking at the look at object.

A reference to the curve node or object you want this object to follow.

The orientation of the object around the path.

The position of the object along the path. 0.0 means at the beginning of the path, and 1.0 means the end. The integer portion of the position is used as the primitive number inside the geometry while the fractional part indicates the u value on the primitive.

If the primitive number does not exist, then it is wrapped back to the beginning. So for numbers greater than 1.0 in a path object that only have a single primitive, it wraps around to the beginning again. You can easily animate something moving around a circular track simply by continuously increasing the position value.

Keyframe this value to animate the object moving along the path.

The Parameterization option controls how position values between 0 and 1 correspond to knots on the path curve.

Controls how the Position parameter is translated into a point on the path curve. Use Arc-length (the default) to interpolate the position values evenly along the physical length of the curve.

Use Uniform to distribute the position values between the knots of the curve. This lets you slow down the object at certain points by bunching up knots in the path curve. However, it is much more convenient to simply edit the animation curve to control the speed of the object along the path.

Orient the object according to the path’s curvature.

The direction vector of the object’s Y axis to orient with.

Controls automatic banking of the object as it turns corners. Set this to 0 to turn automatic banking off.

Toggles the displaying of the link geometry

Defines the relative weighting of rotations about the bone’s x,y,z axis for the Inverse Kinematics solver. These values are relative to the bone’s pre-transform. These are zero by default when created from the object viewer’s Bones tool with the pre-transform rotation values defining the rest angles.

Changes the length of the bone

Specifies the CHOP node from which this bone should obtain its cooking rotations from. This requires that the specified CHOP have 3 tracks that are named as: path:rx, path:ry, and path:rz where path is the full path of this bone without the /obj prefix. This path can be obtained using the opsubpath() expression function.

If this parameter is non-empty on a bone without custom geometry, then the display geometry of the bone will be different to indicate this.

Affects how quickly this bone’s angles can be changed.

Specifies the minimum and maximum rotation angles that this bone can have in each axis. (Only used by IK w/Constraints solver)

Applies damping to the rotation of the bone when the rotation in each axis falls within the specified angle of its minimum or maximum value. The damping occurs when the solved angle is within this angle value from the angle range. (Only used by IK w/Constraints solver)

Specifies the rate at which damping increases as the rotation varies within the damping angle of the minimum or maximum angles. This can also be thought of as the linear slope value at the damping angle region. (Only used by IK w/Constraints solver)

This tab contains similar parameters as capture regions, but they are used for animation and deformation of captured geometry. Notably, the scaling factors can be used to squash and stretch the capture regions during animation.

the length of a bone in the capture mode. This is the bone length when a bone is used for capturing geometry. Note that the capture mode can be turned on by selecting “Settings > Objects > Kinematic Override: capture” from the main menu.

the translation of the bone in the capture mode.

the rotation angles of the bone in the capture mode. Note that the bone rotation axis order is ZYX. Rotation together with Translate and Scale parameters form a transformation that positions a bone in the capture position and orientation with respect to the world space. The transform order for this transformation is Scale, Rotate, Translate.

the scaling of the bone in the capture mode

Path to the Material node.

Whether or not this object is displayed. Turn on the checkbox to have Houdini use this parameter, then set the value to 0 to hide the object, or 1 to show the object. If the checkbox is off, Houdini ignores the value.

Use the specified wireframe color

The display color of the object

Object is capable of being picked in viewport.

Script to run when the object is picked in the viewport. See select scripts .

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.