init

Source/DSP/Envelope.h

@@ -0,0 +1,87 @@
+#pragma once
+#include <cmath>
+#include <algorithm>
+
+enum class ADSRStage { Idle = 0, Attack, Decay, Sustain, Release };
+
+class ADSREnvelope {
+public:
+    void prepare(double sr) {
+        sampleRate = sr;
+        stage = ADSRStage::Idle;
+        level = 0.0f;
+    }
+
+    void setAttack(float a)  { attackTime = std::max(a, 0.001f); }
+    void setDecay(float d)   { decayTime = std::max(d, 0.001f); }
+    void setSustain(float s) { sustainLevel = std::clamp(s, 0.0f, 1.0f); }
+    void setRelease(float r) { releaseTime = std::max(r, 0.001f); }
+
+    void noteOn() {
+        stage = ADSRStage::Attack;
+        level = 0.0f;
+    }
+
+    void noteOff() {
+        if (stage != ADSRStage::Idle)
+            stage = ADSRStage::Release;
+    }
+
+    bool isActive() const { return stage != ADSRStage::Idle; }
+
+    float getNextSample() {
+        switch (stage) {
+            case ADSRStage::Idle:
+                level = 0.0f;
+                break;
+
+            case ADSRStage::Attack: {
+                float attackInc = 1.0f / (attackTime * static_cast<float>(sampleRate));
+                level += attackInc;
+                if (level >= 1.0f) {
+                    level = 1.0f;
+                    stage = ADSRStage::Decay;
+                }
+                break;
+            }
+
+            case ADSRStage::Decay: {
+                float decayInc = (1.0f - sustainLevel) / (decayTime * static_cast<float>(sampleRate));
+                level -= decayInc;
+                if (level <= sustainLevel) {
+                    level = sustainLevel;
+                    stage = ADSRStage::Sustain;
+                }
+                break;
+            }
+
+            case ADSRStage::Sustain:
+                level = sustainLevel;
+                break;
+
+            case ADSRStage::Release: {
+                float releaseInc = level / (releaseTime * static_cast<float>(sampleRate));
+                level -= releaseInc;
+                if (level <= 0.0f) {
+                    level = 0.0f;
+                    stage = ADSRStage::Idle;
+                }
+                break;
+            }
+        }
+
+        return level;
+    }
+
+    float getCurrentLevel() const { return level; }
+    ADSRStage getCurrentStage() const { return stage; }
+
+private:
+    double sampleRate = 44100.0;
+    float attackTime = 0.01f;
+    float decayTime = 0.3f;
+    float sustainLevel = 0.7f;
+    float releaseTime = 0.5f;
+    float level = 0.0f;
+    ADSRStage stage = ADSRStage::Idle;
+};