Layer Proximity Effect

/* broadcastGEMs - Roland Kahlenberg - June 26, 2024.

Proximity Effect based on Layer Boundary

Usually used in Opacity/Scale properties to create a Reactive Effect.

This Expression Rig assumes and requires the Moving Layer and this ProximityFX Layer 
have their Anchor Points centered to their respective Rectangular Boundaries.
*/

// Declare the Moving/Target Layers
const targetLayer1 = thisComp.layer("Moving Layer 1");
const targetLayer2 = thisComp.layer("Moving Layer 2");
// Replace the Layer Names with relevant layer names in your Composition

// Get CompLayer with the ProximityFX Slider Controls
const compLayer = thisComp.layer("Controller");

// Get Maximum Distance and Scale Controls
const maxDistance = compLayer.effect("Proximity - Container - Max Distance")(1);
const minScale = compLayer.effect("Proximity - Container - Min Scale")(1);
const maxScale = compLayer.effect("Proximity - Container - Max Scale")(1);

// Function to calculate distance to a target layer
function calculateDistance(targetLayer) {
 const targetLayerPos = targetLayer.transform.position;
 const targetLayerRect = targetLayer.sourceRectAtTime(time, false);
 const targetLayerScale = targetLayer.transform.scale;
 const targetLayerWidth = targetLayerRect.width * targetLayerScale[0] / 100;
 const targetLayerHeight = targetLayerRect.height * targetLayerScale[1] / 100;
 
 const halfWidthTargetLayer = targetLayerWidth / 2;
 const halfHeightTargetLayer = targetLayerHeight / 2;
 
 const distanceX = Math.max(Math.abs(targetLayerPos[0] - myLayerPos[0]) - (halfWidthThisLayer + halfWidthTargetLayer), 0);
 const distanceY = Math.max(Math.abs(targetLayerPos[1] - myLayerPos[1]) - (halfHeightThisLayer + halfHeightTargetLayer), 0);
 
 return Math.sqrt(distanceX * distanceX + distanceY * distanceY);
}

// Declare this Layer's Position and dimensions
const myLayer = thisLayer;
const myLayerPos = myLayer.transform.position;
const myLayerRect = myLayer.sourceRectAtTime(time, false);
const myLayerScale = myLayer.transform.scale;

const myLayerWidth = myLayerRect.width * myLayerScale[0] / 100;
const myLayerHeight = myLayerRect.height * myLayerScale[1] / 100;

// Calculate the half-width and half-height of this layer's Rect Boundary
const halfWidthThisLayer = myLayerWidth / 2;
const halfHeightThisLayer = myLayerHeight / 2;

// Calculate distances to both target layers
const distance1 = calculateDistance(targetLayer1);
const distance2 = calculateDistance(targetLayer2);

// Use the smaller of the two distances
const distance = Math.min(distance1, distance2);

// Calculate the scale factor based on the distance
const scaleFactor = ease(distance, 0, maxDistance, maxScale, minScale);

// Return the new scale value
[scaleFactor, scaleFactor]

// EndOfExpression