Orientation

With strands, the Orientation attribute is used to align the base particle and the StrandOrientation attribute is used to align the shapes at the StrandPosition values.

If StrandDeform is true, the reference frame for both Orientation and StrandOrientation is established by using the strand's tangent as the Y axis. PointUpVector and StrandUpVector define the X axis.

You can get and set the Orientation attribute with the Get Particle Orientation and Set Particle Orientation compounds, which are simply the Get Data and Set Data nodes with the Orientation attribute already specified.

PointUpVector

Used to establish a reference frame for Orientation on the base particle when using strands and StrandDeform is true. The strand tangent defines the Y axis and this attribute represents the X axis.

If this attribute is not defined, the up-vector is calculated from the camera view, which makes the deformations rotate if the camera moves.

StrandAge

The age of a strand in seconds. This attribute is set and updated by the Create Strands and Generate Strand Trails compounds.

StrandCenter

Set and used by the Strand compounds to control strand deformations.

StrandColor

The color of shapes along a strand.

This attribute is exposed as the Strand Color Gradient option in the Create Strands compound—see Creating Strands. The color is displayed in the render region only if you have an appropriate color gradient shader set up for the particles in the render tree, such as the Particle Density shader or the Particle Strand Gradient shader compound—see Particle Density (ICE) [Particle Shaders].

This attribute does not appear in the list of particle attributes displayed by the Explore button of Get Data and Set Data property editors. If the size of this array does not match StrandPosition, it is ignored.

StrandCount

Set and used by the Strand compounds to keep track of the number of segments in a strand.

This attribute is exposed as the Num Segments option in the Create Strands compound and as the Max Num Segments in the Generate Strand Trails compound—see Creating Strands and Generating Strand Trails.

StrandDeform

Determines whether shapes are lofted along the length of the strand (true) or placed individually at the discrete StrandPosition values (false). Lofting is supported only for Box, Capsule, Cone, and Cylinder shapes.

This attribute is exposed as the Loft Shape Along Strand option in the Create Strands and Generate Strand Trails compounds—see Creating Strands and Generating Strand Trails.

StrandLength

Set and used by the Strand compounds to keep track of the total length of strands.

This attribute is exposed as the Strand Length option in the Create Strands compound—see Creating Strands.

StrandOrientation

Used to orient shapes along a strand.

• If StrandDeform is false, the orientation is relative to the point cloud's local space.

• If StrandDeform is true, StrandOrientation provides an extra rotation that is applied on top of the orientation defined by the strand's tangent and StrandUpVector.

• If StrandOrientation is not defined, the base particle's Orientation is used instead.

The reference for StrandOrientation is established by using the strand's tangent as the Y axis and StrandUpVector as the X axis. If the size of this array does not match StrandPosition, it is ignored.

StrandPosition

The positions of shapes along a strand.

StrandSize

The sizes of shapes along a strand. If this attribute is not defined, the base particles' Size is used instead. If the size of this array does not match StrandPosition, it is ignored.

This attribute is exposed as the Strand Size Profile option in the Create Strands and Generate Strand Trails compounds—see Creating Strands and Generating Strand Trails.

StrandUpVector

Used to establish a reference frame for StrandOrientation if StrandDeform is true. The vector is expressed relative to the point cloud's local space. The strand tangent defines the Y axis and this attribute represents the X axis in the point cloud's local coordinates.

If this attribute is not defined, the up-vector is calculated from the camera, which will make the deformations rotate if the camera moves. If the size of this array does not match StrandPosition, it is ignored.

StrandVelocity

Available for compounds to store the velocities of the shapes at the StrandPosition values. This attribute is set and used by the Create Strands and Generate Strand Trails compounds. This attribute is not updated by the Simulate Particles or Simulate Rigid Bodies nodes.

If this attribute exists, it is used for rendering motion blur. If this attribute is not defined, the base particle's PointVelocity is used instead. If the size of this array does not match StrandPosition, it is ignored.