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Aphelion

Aphelion Editor

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8 — Driving properties over time

Keyframes are not the only way to animate. Property Drive lets a Number connection override any numeric property of any node, which is how you build procedural, non-repetitive motion cheaply.

You will build: an Oscillator driving a Transform 2D's rotation with no keyframes at all.

The two property nodes

NodeDirectionUse
Property Drivevalue → another node's propertyAnimate/override a property from a Number
Property Linkanother node's property → valueRead a property as a Number for math or routing

Both take a node reference: drag the target node's output socket into the target (Drive) or source (Link) input, then choose the property from the Drive → Property / Source → Property dropdown. The dropdown lists that node's numeric properties, grouped by their Properties-panel group.

Steps: procedural rotation

  1. Add a Transform 2D after your footage (Video Input → Transform 2D → Viewer).
  2. Add an Oscillator:
    • Wave → Waveform = Sine
    • Wave → Frequency = 0.25 (cycles per second)
    • Wave → Amplitude = 30
    • Wave → Offset = 0
  3. Add a Property Drive.
  4. Drag Transform 2D.frame into Property Drive.target.
  5. In Property Drive properties, set Drive → Property = Transform · Rotation.
  6. Connect Oscillator.value → Property Drive.value.
  7. Scrub or play. The Transform 2D rotation now oscillates ±30°, driven entirely by the oscillator.

The Drive's Drive → Enabled toggle temporarily suspends the override, and Source → Fallback is the value used while nothing is connected to value.

Useful drivers

DriverWaveform / settingsEffect
OscillatorSine, 0.1–0.5 HzSmooth breathing/pulsing motion
OscillatorTriangleLinear ramps up and down
OscillatorSquare, Wave → DutyHard on/off switching
RandomRandom → Per Frame offOne random value, held
RandomRandom → Per Frame on, Interval = 2A new value every 2 frames — stutter/glitch
Timeline Normalized—0 → 1 across the whole timeline, for a one-way ramp
Timeline Frame—Current frame number
Timeline Time—Current time in seconds
Timeline FPS—Project frame rate
Timeline Max Frame—Last frame of the timeline

Timeline Normalized is the keyframe-free way to ramp a parameter across the whole shot: drive Mix, Opacity, a blur radius, anything.

Combining and scaling

Insert a Math or Math Function node between the driver and the Drive:

Oscillator.value → Math(a) → Property Drive.value

Math → Operation can add, multiply, remap, and so on; Math → A/B provide constants for the operand. Use Clamp to keep a driven property inside a safe range, and Remap to map one range onto another.

Logic → Compare, Logic Gate, Select, Range Check, and Smooth Step let a numeric driver make decisions — for example, "only glitch when the random value is above 0.7".

Reading properties

Property Link is the reverse: point it at a node property and it emits that value as a Number. This is how you feed one node's parameter into another's math without keyframing both.

Tips

  • Driven properties are still keyframable; the drive simply overrides the value while Enabled is on.
  • Drivers are evaluated per frame, so a timeline scrub updates them live.
  • Use Processing → Mix on an effect as a drive target for smooth effect fade-ins without touching keyframes.