modify

The modify statement performs an operation on a node field or local variable. It is used inside a Command node or Coroutine node.

Modify can perform only operations supported by the field type that returns an output of the same type of the modified field or local.

For example, this means that modify on svec3 type fields or locals can be used to apply the scalarmul(sfloat) on the field, but not the dot(svec3). To assign arbitrary values to fields or locals, use the set statement.

Faster operations

The modify statement performs operations faster than using a setfield, setlocal, or set on the same field, so we recommend using modify, especially for onerous operations on large dictionaries (mdstring and dstring) and strings (sjson, stable, sstring).

Comparison of code using set and code using modify.

<Command name="showmenu">

<!-- slower code -->

<set name="menu.position" value="[@ menu.position.add(0 1 0)]" />

<!-- faster code -->

<modify name="menu.position" op="add" value="0 1 0" />

</Command>

Platform support

This node is fully supported on XR-Windows, XR-Portable Windows, XR-Portable iOS, XR-Portable Android, and XR-Portable WASM platforms.

Code example

This is a code example for the modify statement on both fields and locals.

<Command name="showmenu">

<modify name="menu.position" op="scalarmul" value="2.5" />

<local name="position" type="svec3" value="0 1 0" />

<modify name="position" op="cross" value="1 0 0" />

<log text="0 1 0 x 1 0 0 = [@%position%]" />

</Command>

Position

The modify statement can be used only inside a Command node or Coroutine node.

Fields

These are the fields for modify statement.