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The Trail op takes an input op and makes a trail of each point of the input op over the past several frames, and connects the trails in different ways. It will generate trails of any input geometry, whether it is a cube translating, a deforming surface, or particles. This is useful for multi-frame ghosting effects and temporal modeling.
The particles thrown off the end-most points receive a higher velocity than those close to the root of the L-system (enable Points display in Viewport Display):
Temporal modeling with the Trail op: the corners of a translated and rotated cube are used as a source for the Trail op with a Trail Length of 50 frames connected by Columns.
How to construct the trail geometry.
Number of frames in trail.
Number of frames to skip in trail.
Number of frames to cache in RAM.
Resets the cache memory buffer.
Evaluate Within Frame Range
Clamp evaluation between
$FEND, otherwise may
evaluate before start frame.
How to create the output mesh.
Closes the rows in the output mesh.
When computing velocity the resulting velocity will be scaled by this
constant. Note there is an internal scale of
$FPS to convert the
measured change over a frame into a change over a second.
This is the method that is used to approximate the velocity from the point positions.
You can choose between Backward Difference, Central Difference and Forward Difference. Generally, Central Difference gives more accurate results.
Compute Angular Velocity
The difference in orientation of successive frames will be used to
compute an angular velocity,
w, for the points.
N attribute is needed to compute angular velocity. Without
N, the angular velocities are all zero.
Match by Attribute
Points on successive frames will be identified by using the provided integer attribute rather than the point number.
Attribute to Match
The name of the integer or string point attribute to use for matching successive frames.