Drive effects from a blend shape

When to use this

Use a blend shape trigger when something should follow a shape that already moves: a blush that grows with the smile a gesture plays, or eyes that glow while an angry face is on. The shape can be moved by a gesture, face tracking, a toggle of yours, or an animation that Modular Avatar or VRCFury adds.

If a toggle or a parameter should switch the effect, see Link effects to another toggle or a parameter. It is simpler when the source is on or off.

This needs Advanced mode, the default.

Steps

1. In the Hierarchy, select the object that holds your AvatarDoc component.

2. In the inspector's toolbar, press + Trigger. On a narrow inspector, it sits under + More.

   You should now see a trigger named New Trigger, selected under Triggers in the tree.

3. In the trigger's panel, type a name into Name, such as Smile blush, and press Enter.

4. Set When to A blendshape is animated.

   You should now see a Shape row, then Style, Starts at, Fully on at, Swaps at and Mode.

5. Press the button on the Shape row and pick the shape to follow, such as Smile.

6. In Style, keep Smooth to let the effects grow with the shape, or pick Switch to turn them fully on at one weight.

7. With Smooth, set where the effects start and where they are full:

   • Starts at is the shape's weight where the effects start, 0 for a new trigger.
   • Fully on at is the weight where they are fully on, 100 for a new trigger.
   • Swaps at is the weight where objects switch and materials swap, 50 for a new trigger. These cannot grow, so they switch at one point.

   With Switch, set Switch at instead: every effect is on once the shape reaches that weight, and off again when it drops back.

   In the picture, 1 is the shape the trigger follows, 2 Style, 3 Starts at, 4 Fully on at and 5 Mode.

8. In the panel, press + Add effect, then Blendshapes, and pick the shape that follows, such as Blush.

   You should now see a row for Blush, set to Fixed weight, at weight 100.

On a blend shape row, Fixed weight goes from rest to the row's weight as the trigger comes on. Follow source copies the followed shape instead, times Multiplier, and keeps the result between 0 and 100.

Mode decides what happens to the followed shape itself:

• Add, the default, lets the shape move as its own animations say, with the effects on top.
• Replace takes the shape out of every FX animation that moves it. The shape stays at rest and only the effects show, still following where the shape would have been.

To make the trigger work only while something else is true, press + And in the box around the Shape row. That group holds the shape and up to three requirements. While any requirement fails, the effects rest.

What AvatarDoc builds

At upload, AvatarDoc copies the shape's weight into a hidden value in every FX animation that moves the shape, after Modular Avatar and VRCFury have added theirs. The trigger follows that copy. The value is not an expression parameter, so the trigger costs no synced bits: every player's copy of your avatar works it out from the same animations.

Only animations in the FX layer reach the trigger. When the shape also moves in the Gesture, Action or Additive layer, the inspector warns and names those animations.

Check it worked

• In Play mode with Gesture Manager, play the gesture or toggle that moves the followed shape. The effects follow it. See Your first toggle for Play mode.
• The Scene preview row of the trigger says which shape it follows in the scene. When a toggle of yours moves that shape, preview the toggle with On, and the Scene view shows the trigger's effects follow.

If it does not work

• A warning says VRChat moves the shape itself for blinking or lip sync: the trigger never sees those shapes move. Pick a shape your own animations move. See the message.
• A warning says the shape also moves outside the FX layer: the trigger does not follow it there. Move that animation into the FX layer if the trigger should react to it. See the message.
• At upload, a message says no FX animation moves the shape: the effects stay where the shape's resting weight puts them. Animate the shape in an FX animation, or pick one that already moves. See the message.

Related

• Blend shape triggers describes every setting.
• React to touch drives effects from how close a hand is instead.
• A blend shape trigger does nothing in Troubleshooting.