Loops and feedback

Some effects repeat the same steps: layered noise, raymarching, blurs with many samples. Others remember the last frame: trails, echoes, fading paint. Two zones cover these. A zone is a pair of nodes with a coloured box around everything between them.

Repeat

Add Repeat from the picker. You get a Repeat and a Repeat end node inside a teal box.

• count: how many times to repeat, up to 1024.
• value: goes in at the start, is updated on each pass, and comes out of the Repeat end when done.
• index: the current pass, starting at 0.

Repeats count times

Repeat

count

value

value

value

index

Wave

pass 1

uv

frequency

amplitude

phase

vec2

Repeat end

value

value

Drop nodes onto the wire between the two to put them in the loop. Click + value to carry more than one value.

A few limits, which the editor points out for you:

• Values made inside the loop leave through the Repeat end.
• A filter can't read an image that changes on each pass. Changing where it reads, with Resample's uv, works.

Previews inside the box show the first pass (marked pass 1). The Repeat end shows the final result.

Feedback

Add Feedback from the picker. You get a Feedback and a Feedback end node inside a violet box.

• previous is the value from the last frame (0 on the first frame).
• Whatever you connect to the Feedback end is kept for the next frame.

Feeds the next frame

Feedback

previous

Multiply

a

b

any

Max

a

b

any

Feedback end

value

value

float

Dot

float

Output

A simple trail is max(previous × 0.96, dot): the last frame fades a little and the dot is drawn on top. A graph with Feedback always animates.

Feedback updates once per frame, so a trail fades faster on a 60 fps screen than on a 30 fps one. Multiply by deltaTime if you need it to match.

Moving a zone

Drag the box to move everything inside it. Deleting, copying or duplicating one half includes the other.