diff --git a/orx-envelopes/build.gradle.kts b/orx-envelopes/build.gradle.kts
index b104cf60..ac1faec7 100644
--- a/orx-envelopes/build.gradle.kts
+++ b/orx-envelopes/build.gradle.kts
@@ -18,7 +18,8 @@ kotlin {
         @Suppress("UNUSED_VARIABLE")
         val jvmDemo by getting {
             dependencies {
-                implementation(project(":orx-shapes"))
+                implementation(project(":orx-envelopes"))
+                implementation(project(":orx-noise"))
             }
         }
     }
diff --git a/orx-envelopes/src/commonMain/kotlin/ADSR.kt b/orx-envelopes/src/commonMain/kotlin/ADSR.kt
index dd391d86..f84fcbad 100644
--- a/orx-envelopes/src/commonMain/kotlin/ADSR.kt
+++ b/orx-envelopes/src/commonMain/kotlin/ADSR.kt
@@ -8,11 +8,15 @@ data class ADSR(
     val decayDuration: Double,
     val sustainValue: Double,
     val releaseDuration: Double
-) : Envelope{
+) : Envelope() {
     override fun value(t: Double, tOff: Double): Double {
         return adsr(attackDuration, decayDuration, sustainValue, releaseDuration, t, tOff)
     }
 
+    override fun position(t: Double, tOff: Double): Double {
+        return adsrPosition(attackDuration, decayDuration, releaseDuration, t, tOff)
+    }
+
     override fun isActive(t: Double, tOff: Double): Boolean {
         return !(t - tOff > releaseDuration)
     }
@@ -26,12 +30,21 @@ fun adsr(
     t: Double,
     tOff: Double = 1E10
 ): Double {
-
     val da = t / attackDuration
     val dc = (t - attackDuration) / decayDuration
-
     val vOn = mix(min(1.0, da), sustainValue, dc.coerceIn(0.0..1.0))
-
     return mix(vOn, 0.0, ((t - tOff) / releaseDuration).coerceIn(0.0..1.0))
+}
 
+fun adsrPosition(
+    attackDuration: Double,
+    decayDuration: Double,
+    releaseDuration: Double,
+    t: Double,
+    tOff: Double
+): Double {
+    val ta = (t / attackDuration).coerceIn(0.0..1.0)
+    val td = ((t - attackDuration) / decayDuration).coerceIn(0.0..1.0)
+    val tr = ((t - tOff) / releaseDuration).coerceIn(0.0..1.0)
+    return (ta + td + tr) / 3.0
 }
\ No newline at end of file
diff --git a/orx-envelopes/src/commonMain/kotlin/Envelope.kt b/orx-envelopes/src/commonMain/kotlin/Envelope.kt
index 1886af2f..c4c0c6a2 100644
--- a/orx-envelopes/src/commonMain/kotlin/Envelope.kt
+++ b/orx-envelopes/src/commonMain/kotlin/Envelope.kt
@@ -1,7 +1,11 @@
 package org.openrndr.extra.envelopes
 
-interface Envelope {
-    fun value(t: Double, tOff: Double): Double
+abstract class Envelope {
+    abstract fun value(t: Double, tOff: Double): Double
 
-    fun isActive(t: Double, tOff:Double): Boolean
+    abstract fun position(t: Double, tOff: Double): Double
+
+    abstract fun isActive(t: Double, tOff: Double): Boolean
+
+    var objectFunction: ((time: Double, value: Double, position: Double) -> Unit) = { _, _, _ -> }
 }
\ No newline at end of file
diff --git a/orx-envelopes/src/commonMain/kotlin/MPPSynchronize.kt b/orx-envelopes/src/commonMain/kotlin/MPPSynchronize.kt
new file mode 100644
index 00000000..0a5f0b57
--- /dev/null
+++ b/orx-envelopes/src/commonMain/kotlin/MPPSynchronize.kt
@@ -0,0 +1,3 @@
+package org.openrndr.extra.envelopes
+
+expect fun <V> mppSynchronized(lock:Any, f:()->V) : V
\ No newline at end of file
diff --git a/orx-envelopes/src/commonMain/kotlin/Tracker.kt b/orx-envelopes/src/commonMain/kotlin/Tracker.kt
index 00719d06..7279942b 100644
--- a/orx-envelopes/src/commonMain/kotlin/Tracker.kt
+++ b/orx-envelopes/src/commonMain/kotlin/Tracker.kt
@@ -5,42 +5,62 @@ package org.openrndr.extra.envelopes
 import org.openrndr.Clock
 import org.openrndr.extra.parameters.DoubleParameter
 
-class Trigger(val on: Double, var off: Double, val envelope: Envelope)
+class Trigger(val id: Int, val on: Double, var off: Double, val envelope: Envelope)
 
-class TrackerValue(val time: Double, val value: Double)
-abstract class Tracker<T : Envelope>(val clock: Clock) {
-
-    val triggers = mutableListOf<Trigger>()
-
-
-    protected abstract fun createEnvelope(): T
-
-    fun triggerOn() {
-        val t = clock.seconds
-        triggers.removeAll { !it.envelope.isActive(t - it.on, it.off - it.on) }
-        triggers.add(Trigger(clock.seconds, 1E30, createEnvelope()))
+class TrackerValue(
+    val time: Double,
+    val value: Double,
+    val position: Double,
+    val envelope: Envelope
+) {
+    operator fun invoke() {
+        draw()
     }
 
-    fun triggerOff() {
-        val t = clock.seconds
-        triggers.removeAll { !it.envelope.isActive(t - it.on, it.off - it.on) }
-        triggers.lastOrNull()?.let {
-            it.off = clock.seconds
+    fun draw() {
+        envelope.objectFunction(time, value, position)
+    }
+}
+
+abstract class Tracker<T : Envelope>(val clock: Clock) {
+    val triggers = mutableListOf<Trigger>()
+
+    protected abstract fun createEnvelope(objectFunction: (time: Double, value: Double, position: Double) -> Unit): T
+
+    fun triggerOn(
+        triggerId: Int = 0,
+        objectFunction: (time: Double, value: Double, position: Double) -> Unit = { _, _, _ -> }
+    ) {
+        mppSynchronized(triggers) {
+            val t = clock.seconds
+            triggers.removeAll { !it.envelope.isActive(t - it.on, it.off - it.on) }
+            triggers.add(Trigger(triggerId, clock.seconds, 1E30, createEnvelope(objectFunction)))
+        }
+    }
+
+    fun triggerOff(triggerId: Int = 0) {
+        mppSynchronized(triggers) {
+            val t = clock.seconds
+            triggers.removeAll { !it.envelope.isActive(t - it.on, it.off - it.on) }
+            triggers.findLast { it.id == triggerId }?.let {
+                it.off = clock.seconds
+            }
         }
     }
 
     fun values(): List<TrackerValue> {
         val t = clock.seconds
-        return triggers.mapNotNull {
-            val tOn = t - it.on
-            val tOff = it.off - it.on
+        return mppSynchronized(triggers) {
+            triggers.mapNotNull {
+                val tOn = t - it.on
+                val tOff = it.off - it.on
 
-            if (it.envelope.isActive(tOn, tOff)) {
-                val v = it.envelope.value(tOn, tOff)
-
-                TrackerValue(t, v)
-            } else {
-                null
+                if (it.envelope.isActive(tOn, tOff)) {
+                    val v = it.envelope.value(tOn, tOff)
+                    TrackerValue(t, v, it.envelope.position(tOn, tOff), it.envelope)
+                } else {
+                    null
+                }
             }
         }
     }
@@ -48,21 +68,27 @@ abstract class Tracker<T : Envelope>(val clock: Clock) {
     fun value(): Double {
         return values().sumOf { it.value }
     }
-
 }
 
-class ADSRTracker(clock: Clock): Tracker<ADSR>(clock) {
+
+class ADSRTracker(clock: Clock) : Tracker<ADSR>(clock) {
 
     @DoubleParameter("attack", 0.0, 20.0, order = 1)
     var attack: Double = 0.1
+
     @DoubleParameter("decay", 0.0, 20.0, order = 2)
     var decay: Double = 0.1
+
     @DoubleParameter("sustain", 0.0, 1.0, order = 3)
     var sustain: Double = 0.9
+
     @DoubleParameter("release", 0.0, 20.0, order = 4)
     var release: Double = 0.9
 
-    override fun createEnvelope(): ADSR {
-        return ADSR(attack, decay, sustain, release)
+    override fun createEnvelope(objectFunction: (time: Double, value: Double, position: Double) -> Unit): ADSR {
+        return ADSR(attack, decay, sustain, release).apply {
+            this.objectFunction = objectFunction
+        }
     }
-}
\ No newline at end of file
+}
+
diff --git a/orx-envelopes/src/jsMain/kotlin/MPPSynchronize.kt b/orx-envelopes/src/jsMain/kotlin/MPPSynchronize.kt
new file mode 100644
index 00000000..23bf70ac
--- /dev/null
+++ b/orx-envelopes/src/jsMain/kotlin/MPPSynchronize.kt
@@ -0,0 +1,5 @@
+package org.openrndr.extra.envelopes
+
+actual fun <V> mppSynchronized(lock: Any, f: () -> V): V {
+    return f()
+}
\ No newline at end of file
diff --git a/orx-envelopes/src/jvmDemo/kotlin/DemoADSRTracker02.kt b/orx-envelopes/src/jvmDemo/kotlin/DemoADSRTracker02.kt
new file mode 100644
index 00000000..21d250f6
--- /dev/null
+++ b/orx-envelopes/src/jvmDemo/kotlin/DemoADSRTracker02.kt
@@ -0,0 +1,46 @@
+import org.openrndr.application
+import org.openrndr.draw.loadFont
+import org.openrndr.extra.envelopes.ADSRTracker
+import org.openrndr.extra.noise.uniform
+import org.openrndr.shape.Rectangle
+
+fun main() {
+    application {
+        program {
+            val tracker = ADSRTracker(this)
+            tracker.attack = 1.0
+            tracker.decay = 0.2
+            tracker.sustain = 0.8
+            tracker.release = 2.0
+
+            keyboard.keyDown.listen {
+                if (it.name == "t") {
+                    val center = drawer.bounds.uniform(distanceToEdge = 30.0)
+                    tracker.triggerOn(0) { time, value, position ->
+                        drawer.circle(center, value * 100.0)
+                    }
+                }
+                if (it.name == "r") {
+                    val center = drawer.bounds.uniform(distanceToEdge = 30.0)
+                    tracker.triggerOn(1) { time, value, position ->
+                        val r = Rectangle.fromCenter(center, width = value * 100.0, height = value * 100.0)
+                        drawer.rectangle(r)
+                    }
+                }
+            }
+            keyboard.keyUp.listen {
+                if (it.name == "t")
+                    tracker.triggerOff(0)
+                if (it.name == "r")
+                    tracker.triggerOff(1)
+            }
+            extend {
+                tracker.values().forEach {
+                    it()
+                }
+                drawer.fontMap = loadFont("demo-data/fonts/IBMPlexMono-Regular.ttf", 16.0)
+                drawer.text("press and hold 't' and/or 'r'", 20.0, height - 20.0)
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/orx-envelopes/src/jvmMain/kotlin/MPPSynchronize.kt b/orx-envelopes/src/jvmMain/kotlin/MPPSynchronize.kt
new file mode 100644
index 00000000..b23742f3
--- /dev/null
+++ b/orx-envelopes/src/jvmMain/kotlin/MPPSynchronize.kt
@@ -0,0 +1,7 @@
+package org.openrndr.extra.envelopes
+
+actual fun <V> mppSynchronized(lock: Any, f: () -> V): V {
+    return synchronized(lock) {
+        f()
+    }
+}
\ No newline at end of file