`<reference>`#

The so-called reference point is a generalization of a listener point. In a headphone-based reproduction system it corresponds to the position (and orientation) of the listener’s head in the virtual scene. In a loudspeaker-based system there might be multiple listeners, but the loudspeaker setup should still have a single reference point, which is typically somewhere in the center of the setup.

The <reference> can be specified explicitly within the <head> element and it can optionally have static transform attributes like pos and rot, as in the example scene reference-transform.asd:

<asdf version="0.4">
  <head>
    <reference pos="-1 1" rot="-45" />
  </head>
</asdf>

At most one <reference> element can be specified, and it implicitly has the reserved ID "reference", which can be used as the target of a <transform>. If no <reference> element is given, the reference point can still be transformed using apply-to="reference", as in implicit-reference.asd:

<asdf version="0.4">
  <par>
    <clip file="audio/ukewave.ogg" pos="0 0" />
    <transform apply-to="reference">
      <o pos="0 -1" />
      <o pos="-2 1" />
      <o pos="2 1" />
      <o pos="closed" />
    </transform>
  </par>
</asdf>

<reference>#

`<reference>`#