The refDistance
property of the PannerNode
interface is a double value representing the reference distance for reducing volume as the audio source moves further from the listener – i.e. the distance at which the volume reduction starts taking effect. This value is used by all distance models.
The refDistance
property's default value is 1
.
Syntax
var audioCtx = new AudioContext();
var panner = audioCtx.createPanner();
panner.refDistance = 1;
Value
A non-negative number. If the value is set to less than 0, a RangeError
is thrown.
Exceptions
RangeError
- The property has been given a value that is outside the accepted range.
Example
This example demonstrates how different values of refDistance
affect how the volume of a sound decays as it moves away from the listener. Unlike rolloffFactor
, changing this value also delays the volume decay until the sound moves past the reference point.
const context = new AudioContext();
// all our test tones will last this many seconds
const NOTE_LENGTH = 6;
// this is how far we'll move the sound
const Z_DISTANCE = 20;
// this function creates a graph for the test tone with a given refDistance
// and schedules it to move away from the listener along the Z (depth-wise) axis
// at the given start time, resulting in a decrease in volume (decay)
const scheduleTestTone = (refDistance, startTime) => {
const osc = new OscillatorNode(context);
const panner = new PannerNode(context);
panner.refDistance = refDistance;
// set the initial Z position, then schedule the ramp
panner.positionZ.setValueAtTime(0, startTime);
panner.positionZ.linearRampToValueAtTime(Z_DISTANCE, startTime + NOTE_LENGTH);
osc.connect(panner)
.connect(context.destination);
osc.start(startTime);
osc.stop(startTime + NOTE_LENGTH);
};
// this tone should decay immediately and fairly quickly
scheduleTestTone(1, context.currentTime);
// this tone should decay slower and later than the previous one
scheduleTestTone(4, context.currentTime + NOTE_LENGTH);
// this tone should decay only slightly, and only start decaying fairly late
scheduleTestTone(7, context.currentTime + NOTE_LENGTH * 2);
After running this code, the resulting waveforms should look something like this:
[[File:../../../../../../media.prod.mdn.mozit.cloud/attachments/2018/10/11/16243/5f6251b83ac11c6ad9cf02b9137b2dce/Screen_Shot_2018-10-11_at_23.14.32.png|A waveform visualisation of three oscillator tones produced in Web Audio. Each oscillator moves away from the listener at the same speed, but with different refDistances affecting the resulting volume decay.]]
Specifications
Specification | Status | Comment |
Web Audio APIThe definition of 'refDistance' in that specification. | Working Draft |
Browser compatibility
The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Update compatibility data on GitHub
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
refDistance
|
Chrome
Full support 14 |
Edge
Full support 12 |
Firefox
Full support 25 |
IE
No support No |
Opera
Full support 15 |
Safari
Full support 6 |
WebView Android
Full support Yes |
Chrome Android
Full support 18 |
Firefox Android
Full support 26 |
Opera Android
Full support 14 |
Safari iOS
? |
Samsung Internet Android
Full support 1.0 |
Legend
- Full support
- Full support
- No support
- No support
- Compatibility unknown
- Compatibility unknown
See also
PannerNode.refDistance by Mozilla Contributors is licensed under CC-BY-SA 2.5.