PannerNode.rolloffFactor

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rolloffFactor 特性为 PannerNode interface is a double value describing how quickly the volume is reduced as the source moves away from the listener. This value is used by all distance models.The rolloffFactor property's default value is 1 .

句法

var audioCtx = new AudioContext();
var panner = audioCtx.createPanner();
panner.rolloffFactor = 1;

值

A number whose range depends on the distanceModel of the panner as follows (negative values are not allowed):

" linear "
" inverse "
" exponential "

异常

RangeError

范例

This example demonstrates how different rolloffFactor values affect how the volume of the test tone decreases with increasing distance from the listener:

const context = new AudioContext();
// all our test tones will last this many seconds
const NOTE_LENGTH = 4;
// 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 rolloffFactor
// 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 = (rolloffFactor, startTime) => {
  const osc = new OscillatorNode(context);
  const panner = new PannerNode(context);
  panner.rolloffFactor = rolloffFactor;
  // 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 fairly quickly
scheduleTestTone(1, context.currentTime);
// this tone should decay slower than the previous one
scheduleTestTone(0.5, context.currentTime + NOTE_LENGTH);
// this tone should decay only slightly
scheduleTestTone(0.1, context.currentTime + NOTE_LENGTH * 2);

After running this code, the resulting waveforms should look something like this:

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 rolloffFactors affecting the resulting volume decay.

规范

规范	状态	注释
Web 音频 API The definition of 'rolloffFactor' in that specification.	工作草案

浏览器兼容性

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. 更新 GitHub 上的兼容性数据

	桌面						移动
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`rolloffFactor`	Chrome 14	Edge 12	Firefox 25	IE 不支持 No	Opera 15	Safari 6	WebView Android Yes	Chrome Android 18	Firefox Android 26	Opera Android 14	Safari iOS ?	Samsung Internet Android 1.0

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元数据

最后修改： 2020 年 1 月 22 日

Web 音频 API
PannerNode
构造函数
1. PannerNode()
特性
1. coneInnerAngle
2. coneOuterAngle
3. coneOuterGain
4. distanceModel
5. maxDistance
6. orientationX
7. orientationY
8. orientationZ
9. panningModel
10. positionX
11. positionY
12. positionZ
13. refDistance
14. rolloffFactor
方法
继承：
1. AudioNode
2. EventTarget
Related pages for Web Audio API

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句法

值

异常

范例

规范

浏览器兼容性

图例

另请参阅

相关话题