Why does my Set Attribute from Curve always output the same value?

The Sample Time input defaults to 0 (or the constant Time node). Connect Age over Lifetime (0..1 ratio) to the Sample Time input so the curve evaluates per particle as it ages.

What's Age vs Lifetime?

Age is seconds since spawn; Lifetime is total. Age over Lifetime (Age / Lifetime) is normalized 0..1 and is the right input for curves.

Per-particle randomness?

Multiply by a random factor before sampling, or use Set Attribute from Curve with Random Per Particle source to vary across instances.

Fix: VFX Graph Set Attribute From Curve Flat

Quick answer: Connect Age over Lifetime to Sample Time. Default zero produces flat output.

Color over lifetime curve goes red → black. Particles render solid red. Sample Time input wasn’t connected; defaulted to 0, sampling start of curve forever.

The Fix

Particle Update:
  Age over Lifetime (computed)  →  Sample Time
  Set Color from Curve  (color curve, red→black)

// Curve sampled at age/lifetime each tick.
// At spawn: 0 (red). At end: 1 (black).

Per-particle Age over Lifetime ranges 0..1. Curve sampled accordingly. Same node available in Init or Update; Update gives time variation.

Verifying

Particles age red → black. Without connection: stays red. Curve preview shows the gradient correctly.

“Age over Lifetime in. Curve evaluates. Lifecycle visible.”

Related Issues

For VFX strip, see strip. For VFX Spawn Over Distance, see distance.

Age over Lifetime. Curve sweeps.