Every Synapse layer carries one effect named Synapse. Select the Synapse layer and open the Effect Controls panel to see it. Its controls change every line in that Synapse at once, and each one can be keyframed or driven by an expression.
Width and color
Width is the stroke width in pixels and Color is the stroke color, white by default. A new Synapse starts at the Line Width from settings, 2 px unless you change it.
For glows, add effects like Glow to the Synapse layer itself. It’s a normal shape layer, so blending modes, track mattes and layer styles work too.
Let the lines sag
Slack bends each line like a rope under gravity. A level line’s middle drops by the Slack value in pixels. A tilted line drops less, and an upright line stays straight, so lines never flip from one side to the other as layers move.
A negative Slack bows the lines upward.
Keep lines off your layers
Inset stops every line short of both of its layers by that many pixels, so a line meets the edge of a dot instead of its center. A line too short for its inset disappears until its layers move apart again. A new Synapse starts at the Inset from settings.
Draw the lines on
Draw On is the share of each line that’s drawn, from 0% to 100%. Every line grows from its first layer: Chain lines from the earlier layer in the chain, Hub lines from the hub. Keyframe it from 0% to 100% to draw a constellation in.
Tune Web’s reach
Max Distance and Fade Distance only affect lines made with Web. A Web line shows while its two layers are closer than Max Distance. Over the last Fade Distance it fades out in eight steps, and past Max Distance it’s gone.
Lower Max Distance for a sparse web, raise it for a dense one. Raise Fade Distance for softer fades. Lines made with Chain, Hub or two clicked stars always show at full strength, even in a Synapse that also has Web lines.
Where the lines attach
Each line runs between its layers’ anchor points as they appear in the comp. That holds for animated layers, parented layers, and 3D layers seen through the active camera. A light attaches at its position.
The lines are drawn by expressions on the Synapse layer, so you don’t bake or update anything when the layers change. Move a layer, re-time it or parent it, and its lines follow.