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Add multiplicative envelope

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This commit is contained in:
Paul Ferrand 2020-03-30 21:32:50 +02:00
parent 1523a14ee8
commit 9e3f496f9e
1 changed files with 20 additions and 0 deletions
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20
src/sfizz/SfzHelpers.h
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@ -361,5 +361,25 @@ void linearEnvelope(const EventVector& events, absl::Span<float> envelope, F&& l
fill<float>(envelope.subspan(lastDelay), lastValue);
}
template<class F>
void multiplicativeEnvelope(const EventVector& events, absl::Span<float> envelope, F&& lambda)
{
ASSERT(events.size() > 0);
ASSERT(events[0].delay == 0);
auto lastValue = lambda(events[0].value);
auto lastDelay = events[0].delay;
for (unsigned i = 1; i < events.size(); ++ i) {
const auto event = events[i];
const auto length = event.delay - lastDelay;
const auto nextValue = lambda(event.value);
const auto step = std::exp((std::log(nextValue) - std::log(currentValue)) / length);
multiplicativeRamp<float>(envelope.subspan(lastDelay, length), lastValue, step);
lastValue = nextValue;
lastDelay += length;
}
fill<float>(envelope.subspan(lastDelay), lastValue);
}
} // namespace sfz