Envelope
Categories:
GS_Core::Envelope provides an ADSR envelope — the attack / decay / sustain / release shape borrowed from synthesis, generalised for any value that needs to rise, hold and fall over time.
It is a general-purpose utility, not an audio one. Anywhere a value should ramp in, hold, and ramp out — a shake intensity, a feedback effect’s strength, a UI element’s emphasis — an envelope describes that shape as data instead of as hand-written timing code.
For usage guides and setup examples, see The Basics: GS_Core.
Contents
ADSREnvelope
A reflected struct, so it can be authored directly on a component or asset and tuned in the Inspector.
| Field | Default | Description |
|---|---|---|
| Attack | 0.05 | Seconds to rise from zero to full. |
| Decay | 0.10 | Seconds to fall from full to the sustain level. |
| Sustain | 0.00 | Seconds to hold at the sustain level. |
| Release | 0.30 | Seconds to fall from the sustain level to zero. |
| Sustain Level | 1.0 | The level held during the sustain phase. |
The defaults describe an attack-release shape — a quick rise and a slower fall with no hold, which is what most one-shot effects want. Give Sustain a non-zero duration when the value should stay up for a while before releasing.
Being reflected is the point: a designer authors the envelope on the component, and the code just evaluates it.
Functions
| Function | Returns | Description |
|---|---|---|
Evaluate(elapsed, envelope) | float | The envelope’s value at a given elapsed time. |
TotalDuration(envelope) | float | Attack + decay + sustain + release. |
IsFinished(elapsed, envelope) | bool | Whether the envelope has completed. |
IsFinished is worth using rather than comparing against TotalDuration yourself — it is the signal to stop evaluating and shut the effect down, which is the cheaper path when many effects are running.
Usage
The pattern is always the same: accumulate elapsed time, evaluate, and stop when finished.
#include <GS_Core/Utility/Math/EnvelopeUtility.h>
// each tick, while active
m_elapsed += deltaTime;
const float gain = GS_Core::Envelope::Evaluate(m_elapsed, m_envelope);
ApplyGain(gain);
if (GS_Core::Envelope::IsFinished(m_elapsed, m_envelope))
{
m_active = false;
}
Reset m_elapsed to zero to retrigger. Because the envelope is data, retriggering with a different shape is a matter of swapping the struct rather than changing any of this code.
See Also
For related utilities:
- Easing Curves — shaping a single transition rather than a full envelope
- Noise — continuous variation rather than a one-shot shape
- Gradients — value over a normalized range rather than over time
For conceptual overviews and usage guides:
Get GS_Core
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