Duplicate Layer

Layer_other_duplicate_icon.png

About Duplicate Layer

The Duplicate Layer makes multiple copies of the layers under it in real time.

The Duplicate Layer works like a loop over the content below it and provides a changing variable to that content. This variable (the Export Index) can now be used (Connect) within that content.

Parameters of Duplicate Layer

The parameters of the Duplicate Layers are:

Name

Value

Type

Real_icon.png Z Depth Parameter

0.000000

real

Real_icon.png Opacity

1.000000

real

Integer_icon.png Blend Method

Composite

integer

Real_icon.png Index Valuenode_icon.png

3.000000

Duplicate

The Index Parameter

The Index is automatically Export. This is the only ValueNode that will change from one copy to the next. This exported value can then be selected in the Library Panel and Connect to the parameter(s) in the layer under the duplicate dialog which should change in the copies.

The Index parameter has 3 sub-parameters, From, To, and Step. The value of the exported Index parameter varies from the value of From to the value of To in steps of size Step.

From can be higher or lower than To. It doesn’t matter whether Step is positive or negative. The steps will be in the direction from From to To.

The duplicated layers are placed in the layer stack in order, so that those corresponding to the From value will appear lower down (i.e. least visible with normal composite blend mode) than those corresponding to the To value (most visible).

Known Problems

  • The Duplicate Layer doesn’t do anything about bounding boxes. Doing so could help to speed up rendering when the duplicated layers are outside the visible area. It’s not clear how useful or possible this would be. To calculate its bounding box, the duplicate layer would need to loop through all values of Index to get the underlying bounding boxes and union them together. Maybe it’s worth doing anyway.

  • Editing a Spline below a Duplicate Layer becomes very difficult while a recent edit is still being rendered, because the Spline Handles move around as the render runs (if the duplications are at different positions or scale). I tried using the same mutex around the Duplicate ValueNode’s operator() method as is used in the Duplicate Layer’s code, but it lead to a deadlock.