obs.currentValue = computed([obs.mode, obs.quantize, inverted, param], function (mode, quantize, inverted, param) {
if (param != null) {
if (inverted) {
param = Sum([1, Negate(param)])
}
if (mode === 'exp') {
param = Square(param)
}
var result = Sum([
Multiply([param, Abs(range)]),
when(inverted, obs.maxValue, obs.minValue)
])
if (quantize) {
result = Quantize(result, quantize)
}
return result
} else {
return obs.minValue.currentValue
}
}, {
function LinkParam (context) {
var obs = ObservStruct({
param: Value(),
minValue: Param(context, 0),
maxValue: Param(context, 1),
mode: Prop('linear'),
quantize: Prop(0)
})
var releases = []
obs._type = 'LinkParam'
obs.context = context
var range = Sum([
obs.maxValue,
Negate(obs.minValue)
])
releases.push(
watch(range) // HACK: avoid regenerating transform AudioNodes
)
// only relink params if the param we want changes
var param = computed([context.paramLookup, obs.param], (paramLookup, paramId) => {
return context.paramLookup.get(paramId)
}, {
passthru: true // treat nested observables as values instead of expanding
})
var inverted = computed([range], range => {
return getValue(range, context.audio.currentTime) < 0
})
obs.currentValue = computed([obs.mode, obs.quantize, inverted, param], function (mode, quantize, inverted, param) {
if (param != null) {
if (inverted) {
param = Sum([1, Negate(param)])
}
if (mode === 'exp') {
param = Square(param)
}
var result = Sum([
Multiply([param, Abs(range)]),
when(inverted, obs.maxValue, obs.minValue)
])
if (quantize) {
result = Quantize(result, quantize)
}
return result
} else {
return obs.minValue.currentValue
}
}, {
nextTick: true,
comparer: (a, b) => {
// also compare AudioNodes and ParamSources
if (a instanceof global.AudioNode || ParamSource.isParam(a)) {
return a === b
}
}
})
obs.destroy = function () {
Param.destroy(obs)
while (releases.length) {
releases.pop()()
}
}
return obs
}