After Effects tutorial: link path points AND tangents to nulls

By 24th October 2017Tutorials
AE link points and tangents to nulls

After Effects CC2018 introduced a really neat script which allows you to create nulls based on the position of points on a path, that you can then use to control the path’s shape. While this is really useful (and hasn’t been an integral part of AE before, although there have been workarounds with plugins like BAO Mask Avenger), it doesn’t create nulls for path tangents – which means that for curved paths, you’re stuck with whatever curvature you started with whenever you move a point.

So, we’ve added extra functionality to this After Effects script so it now creates a null for each tangent (in and out) as well as the points on the path, too. Tangent nulls are parented to their path nulls, so when you move a path point, the two tangents also move. This does mean a lot of nulls, but hey, you pays your money, you takes your choice.

You can download the script from this link: https://we.tl/kYy2DkI4pZ

And here’s the full script.
/*
Create Nulls From Paths.jsx v.0.6
Updated 24 Oct 2017 by Nick Hill, nomagnolia.tv
Attach nulls to shape and mask vertices, and vice-versa.
Changes:
- wraps it all in an IIFE
- fixes call to missing method array.indexOf
*/
(function createNullsFromPaths (thisObj) {
// Build UI
function buildUI(thisObj) {
var windowTitle = localize("$$$/AE/Script/CreatePathNulls/CreateNullsFromPaths=Create Nulls From Paths");
var firstButton = localize("$$$/AE/Script/CreatePathNulls/PathPointsToNulls=Points Follow Nulls");
var secondButton = localize("$$$/AE/Script/CreatePathNulls/NullsToPathPoints=Nulls Follow Points");
var thirdButton = localize("$$$/AE/Script/CreatePathNulls/TracePath=Trace Path");
var fourthButton = localize("$$$/AE/Script/CreatePathNulls/PathTangentsFollowNulls=Points and Tangents follow Nulls");
var win = (thisObj instanceof Panel)? thisObj : new Window('palette', windowTitle);
win.spacing = 0;
win.margins = 4;
var myButtonGroup = win.add ("group");
myButtonGroup.spacing = 4;
myButtonGroup.margins = 0;
myButtonGroup.orientation = "row";
win.button1 = myButtonGroup.add ("button", undefined, firstButton);
win.button2 = myButtonGroup.add ("button", undefined, fourthButton);
win.button3 = myButtonGroup.add ("button", undefined, secondButton);
win.button4 = myButtonGroup.add ("button", undefined, thirdButton);
myButtonGroup.alignment = "center";
myButtonGroup.alignChildren = "center";
win.button1.onClick = function(){
linkPointsToNulls();
}
win.button2.onClick = function(){
linkPointsAndTangentsToNulls();
}
win.button3.onClick = function(){
linkNullsToPoints();
}
win.button4.onClick = function(){
tracePath();
}
win.layout.layout(true);
return win
}
// Show the Panel
var w = buildUI(thisObj);
if (w.toString() == "[object Panel]") {
w;
} else {
w.show();
}
/* General functions */
function getActiveComp(){
var theComp = app.project.activeItem;
if (theComp == undefined){
var errorMsg = localize("$$$/AE/Script/CreatePathNulls/ErrorNoComp=Error: Please select a composition.");
alert(errorMsg);
return null
}
return theComp
}
function getSelectedLayers(targetComp){
var targetLayers = targetComp.selectedLayers;
return targetLayers
}
function createNull(targetComp){
return targetComp.layers.addNull();
}
function getSelectedProperties(targetLayer){
var props = targetLayer.selectedProperties;
if (props.length < 1){
return null
}
return props
}
function forEachLayer(targetLayerArray, doSomething) {
for (var i = 0, ii = targetLayerArray.length; i < ii; i++){
doSomething(targetLayerArray[i]);
}}
function forEachProperty(targetProps, doSomething){
for (var i = 0, ii = targetProps.length; i < ii; i++){
doSomething(targetProps[i]);
}}
function forEachEffect(targetLayer, doSomething){
for (var i = 1, ii = targetLayer.property("ADBE Effect Parade").numProperties; i <= ii; i++) {
doSomething(targetLayer.property("ADBE Effect Parade").property(i));
}}
function matchMatchName(targetEffect,matchNameString){
if (targetEffect != null && targetEffect.matchName === matchNameString) {
return targetEffect
} else {
return null
}}
function getPropPath(currentProp,pathHierarchy){
var pathPath = "";
while (currentProp.parentProperty !== null){
if ((currentProp.parentProperty.propertyType === PropertyType.INDEXED_GROUP)) {
pathHierarchy.unshift(currentProp.propertyIndex);
pathPath = "(" + currentProp.propertyIndex + ")" + pathPath;
} else {
pathPath = "(\"" + currentProp.matchName.toString() + "\")" + pathPath;
}
// Traverse up the property tree
currentProp = currentProp.parentProperty;
}
return pathPath
}
function getPathPoints(path){
return path.value.vertices;
}
function getPathInTangents(path){
return path.value.inTangents;
}
function getPathOutTangents(path){
return path.value.outTangents;
}
/* Project specific code */
function forEachPath(doSomething){
var comp = getActiveComp();
if(comp == null) {
return
}
var selectedLayers = getSelectedLayers(comp);
if (selectedLayers == null){
return
}
// First store the set of selected paths
var selectedPaths = [];
var parentLayers = [];
forEachLayer(selectedLayers,function(selectedLayer){
var paths = getSelectedProperties(selectedLayer);
if (paths == null){
return
}
forEachProperty(paths,function(path){
var isShapePath = matchMatchName(path,"ADBE Vector Shape");
var isMaskPath = matchMatchName(path,"ADBE Mask Shape");
// var isPaintPath = matchMatchName(path,"ADBE Paint Shape"); //Paint and roto strokes not yet supported in scripting
if(isShapePath != null || isMaskPath != null ){
selectedPaths.push(path);
parentLayers.push(selectedLayer);
}});
});
// Then operate on the selection
if (selectedPaths.length == 0){
var pathError = localize("$$$/AE/Script/CreatePathNulls/ErrorNoPathsSelected=Error: No paths selected.");
alert(pathError);
return
}
for (var p = 0; p < selectedPaths.length; p++) {
doSomething(comp,parentLayers[p],selectedPaths[p]);
}}
function linkNullsToPoints(){
var undoGroup = localize("$$$/AE/Script/CreatePathNulls/LinkNullsToPathPoints=Link Nulls to Path Points");
app.beginUndoGroup(undoGroup);
forEachPath(function(comp,selectedLayer,path){
var pathHierarchy = [];
var pathPath = getPropPath(path, pathHierarchy);
// Do things with the path points
var pathPoints = getPathPoints(path);
for (var i = 0, ii = pathPoints.length; i < ii; i++){
var nullName = selectedLayer.name + ": " + path.parentProperty.name + " [" + pathHierarchy.join(".") + "." + i + "]";
if(comp.layer(nullName) == undefined){
var newNull = createNull(comp);
newNull.position.setValue(pathPoints[i]);
newNull.position.expression =
"var srcLayer = thisComp.layer(\"" + selectedLayer.name + "\"); \r" +
"var srcPath = srcLayer" + pathPath + ".points()[" + i + "]; \r" +
"srcLayer.toComp(srcPath);";
newNull.name = nullName;
newNull.label = 10;
}}
});
app.endUndoGroup();
}
function linkPointsToNulls(){
var undoGroup = localize("$$$/AE/Script/CreatePathNulls/LinkPathPointsToNulls=Link Path Points to Nulls");
app.beginUndoGroup(undoGroup);
forEachPath(function(comp,selectedLayer,path){
// Get property path to path
var pathHierarchy = [];
var pathPath = getPropPath(path, pathHierarchy);
var nullSet = [];
// Do things with the path points
var pathPoints = getPathPoints(path);
for (var i = 0, ii = pathPoints.length; i < ii; i++){ //For each path point
var nullName = selectedLayer.name + ": " + path.parentProperty.name + " [" + pathHierarchy.join(".") + "." + i + "]";
nullSet.push(nullName);
// Get names of nulls that don't exist yet and create them
if(comp.layer(nullName) == undefined){
//Create nulls
var newNull = createNull(comp);
// Null layer name
newNull.name = nullName;
newNull.label = 11;
// Set position using layer space transforms, then remove expressions
newNull.position.setValue(pathPoints[i]);
newNull.position.expression =
"var srcLayer = thisComp.layer(\"" + selectedLayer.name + "\"); \r" +
"var srcPath = srcLayer" + pathPath + ".points()[" + i + "]; \r" +
"srcLayer.toComp(srcPath);";
newNull.position.setValue(newNull.position.value);
newNull.position.expression = '';
}}
// Get any existing Layer Control effects
var existingEffects = [];
forEachEffect(selectedLayer,function(targetEffect){
if(matchMatchName(targetEffect,"ADBE Layer Control") != null) {
existingEffects.push(targetEffect.name);
}});
// Add new layer control effects for each null
for(var n = 0; n < nullSet.length;n++){
if(existingEffects.join("|").indexOf(nullSet[n]) != -1){ //If layer control effect exists, relink it to null
selectedLayer.property("ADBE Effect Parade")(nullSet[n]).property("ADBE Layer Control-0001").setValue(comp.layer(nullSet[n]).index);
} else {
var newControl = selectedLayer.property("ADBE Effect Parade").addProperty("ADBE Layer Control");
newControl.name = nullSet[n];
newControl.property("ADBE Layer Control-0001").setValue(comp.layer(nullSet[n]).index);
}}
// Set path expression that references nulls
path.expression =
"var nullLayerNames = [\"" + nullSet.join("\",\"") + "\"]; \r" +
"var origPath = thisProperty; \r" +
"var origPoints = origPath.points(); \r" +
"var origInTang = origPath.inTangents(); \r" +
"var origOutTang = origPath.outTangents(); \r" +
"var getNullLayers = []; \r" +
"for (var i = 0; i < nullLayerNames.length; i++){ \r" +
" try{ \r" +
" getNullLayers.push(effect(nullLayerNames[i])(\"ADBE Layer Control-0001\")); \r" +
" } catch(err) { \r" +
" getNullLayers.push(null); \r" +
" }} \r" +
"for (var i = 0; i < getNullLayers.length; i++){ \r" +
" if (getNullLayers[i] != null && getNullLayers[i].index != thisLayer.index){ \r" +
" origPoints[i] = fromCompToSurface(getNullLayers[i].toComp(getNullLayers[i].anchorPoint)); \r" +
" }} \r" +
"createPath(origPoints,origInTang,origOutTang,origPath.isClosed());";
});
app.endUndoGroup();
}
function linkPointsAndTangentsToNulls(){
var undoGroup = localize("$$$/AE/Script/CreatePathNulls/LinkPathPointsAndTangentsToNulls=Link Path Points and Tangents to Nulls");
app.beginUndoGroup(undoGroup);
forEachPath(function(comp,selectedLayer,path){
// get current comp and layer object
var curComp = app.project.activeItem;
if (!curComp || !(curComp instanceof CompItem)) {
alert('noComp');
return;
}
// Get property path to path
var pathHierarchy = [];
var pathPath = getPropPath(path, pathHierarchy);
var nullSet = [];
var nullInSet = [];
var nullOutSet = [];
// Do things with the path points
var pathPoints = getPathPoints(path);
var pathInTangents = getPathInTangents(path); // there will be two tangents for each point except the first and last, if the path's open
var pathOutTangents = getPathOutTangents(path);
for (var i = 0, ii = pathPoints.length; i < ii; i++){ //For each path point
var nullName = selectedLayer.name + ": " + path.parentProperty.name + " [" + pathHierarchy.join(".") + "." + i + "]";
nullSet.push(nullName);
// Get names of nulls that don't exist yet and create them
if(comp.layer(nullName) == undefined){
//Create nulls
var newNull = createNull(comp);
// Null layer name
newNull.name = nullName;
newNull.label = 11;
// Set position using layer space transforms, then remove expressions
newNull.position.setValue(pathPoints[i]);
newNull.position.expression =
"var srcLayer = thisComp.layer(\"" + selectedLayer.name + "\"); \r" +
"var srcPath = srcLayer" + pathPath + ".points()[" + i + "]; \r" +
"srcLayer.toComp(srcPath);";
newNull.position.setValue(newNull.position.value);
newNull.position.expression = '';
}}
for (var i = 0, ii = pathInTangents.length; i < ii; i++){ //For each path point
var nullName = selectedLayer.name + ": " + path.parentProperty.name + " IN [" + pathHierarchy.join(".") + "." + i + "]";
nullInSet.push(nullName);
// Get names of nulls that don't exist yet and create them
if(comp.layer(nullName) == undefined){
//Create nulls
var newNull = createNull(comp);
// Null layer name
newNull.name = nullName;
newNull.label = 10; // purple
// Set position using layer space transforms, then remove expressions
newNull.position.setValue(pathInTangents[i]);
newNull.position.expression =
"var srcLayer = thisComp.layer(\"" + selectedLayer.name + "\"); \r" +
"var srcPath = srcLayer" + pathPath + ".points()[" + i + "] + srcLayer" + pathPath + ".inTangents()[" + i + "]; \r" +
"srcLayer.toComp(srcPath);";
newNull.position.setValue(newNull.position.value);
newNull.position.expression = '';
newNull.parent = comp.layer(nullSet[i]);
}}
for (var i = 0, ii = pathOutTangents.length; i < ii; i++){ //For each path point
var nullName = selectedLayer.name + ": " + path.parentProperty.name + " OUT [" + pathHierarchy.join(".") + "." + i + "]";
nullOutSet.push(nullName);
// Get names of nulls that don't exist yet and create them
if(comp.layer(nullName) == undefined){
//Create nulls
var newNull = createNull(comp);
// Null layer name
newNull.name = nullName;
newNull.label = 9; // green
// Set position using layer space transforms, then remove expressions
newNull.position.setValue(pathOutTangents[i]);
newNull.position.expression =
"var srcLayer = thisComp.layer(\"" + selectedLayer.name + "\"); \r" +
"var srcPath = srcLayer" + pathPath + ".points()[" + i + "] + srcLayer" + pathPath + ".outTangents()[" + i + "]; \r" +
"srcLayer.toComp(srcPath);";
newNull.position.setValue(newNull.position.value);
newNull.position.expression = '';
newNull.parent = comp.layer(nullSet[i]);
}}
// Get any existing Layer Control effects
var existingEffects = [];
forEachEffect(selectedLayer,function(targetEffect){
if(matchMatchName(targetEffect,"ADBE Layer Control") != null) {
existingEffects.push(targetEffect.name);
}});
// Add new layer control effects for each null
for(var n = 0; n < nullSet.length;n++){
if(existingEffects.join("|").indexOf(nullSet[n]) != -1){ //If layer control effect exists, relink it to null
selectedLayer.property("ADBE Effect Parade")(nullSet[n]).property("ADBE Layer Control-0001").setValue(comp.layer(nullSet[n]).index);
} else {
var newControl = selectedLayer.property("ADBE Effect Parade").addProperty("ADBE Layer Control");
newControl.name = nullSet[n];
newControl.property("ADBE Layer Control-0001").setValue(comp.layer(nullSet[n]).index);
}}
for(var n = 0; n < nullInSet.length;n++){
if(existingEffects.join("|").indexOf(nullInSet[n]) != -1){ //If layer control effect exists, relink it to null
selectedLayer.property("ADBE Effect Parade")(nullInSet[n]).property("ADBE Layer Control-0001").setValue(comp.layer(nullInSet[n]).index);
} else {
var newControl = selectedLayer.property("ADBE Effect Parade").addProperty("ADBE Layer Control");
newControl.name = nullInSet[n];
newControl.property("ADBE Layer Control-0001").setValue(comp.layer(nullInSet[n]).index);
}}
for(var n = 0; n < nullOutSet.length;n++){
if(existingEffects.join("|").indexOf(nullOutSet[n]) != -1){ //If layer control effect exists, relink it to null
selectedLayer.property("ADBE Effect Parade")(nullOutSet[n]).property("ADBE Layer Control-0001").setValue(comp.layer(nullOutSet[n]).index);
} else {
var newControl = selectedLayer.property("ADBE Effect Parade").addProperty("ADBE Layer Control");
newControl.name = nullOutSet[n];
newControl.property("ADBE Layer Control-0001").setValue(comp.layer(nullOutSet[n]).index);
}}
// Set path expression that references nulls
path.expression =
"var nullPointLayerNames = [\"" + nullSet.join("\",\"") + "\"]; \r" +
"var nullTanInLayerNames = [\"" + nullInSet.join("\",\"") + "\"]; \r" +
"var nullTanOutLayerNames = [\"" + nullOutSet.join("\",\"") + "\"]; \r" +
"var origPath = thisProperty; \r" +
"var origPoints = origPath.points(); \r" +
"var origInTang = origPath.inTangents(); \r" +
"var origOutTang = origPath.outTangents(); \r" +
"var getNullLayers = []; \r" +
"var getNullIns = []; \r" +
"var getNullOuts = []; \r" +
"for (var i = 0; i < nullPointLayerNames.length; i++){ \r" +
" try{ \r" +
" getNullLayers.push(effect(nullPointLayerNames[i])(\"ADBE Layer Control-0001\")); \r" +
" getNullIns.push(effect(nullTanInLayerNames[i])(\"ADBE Layer Control-0001\")); \r" +
" getNullOuts.push(effect(nullTanOutLayerNames[i])(\"ADBE Layer Control-0001\")); \r" +
" } catch(err) { \r" +
" getNullLayers.push(null); \r" +
" getNullIns.push(null); \r" +
" getNullOuts.push(null); \r" +
" }} \r" +
"for (var i = 0; i < getNullLayers.length; i++){ \r" +
" if (getNullLayers[i] != null && getNullLayers[i].index != thisLayer.index){ \r" +
" origPoints[i] = fromCompToSurface(getNullLayers[i].toComp(getNullLayers[i].anchorPoint)); \r" +
" } \r" +
" if (getNullIns[i] != null && getNullIns[i].index != thisLayer.index){ \r" +
" origInTang[i] = fromCompToSurface(getNullIns[i].toComp(getNullIns[i].anchorPoint)) - origPoints[i]; \r" +
" } \r" +
" if (getNullOuts[i] != null && getNullOuts[i].index != thisLayer.index){ \r" +
" origOutTang[i] = fromCompToSurface(getNullOuts[i].toComp(getNullOuts[i].anchorPoint)) - origPoints[i]; \r" +
" }} \r" +
"createPath(origPoints,origInTang,origOutTang,origPath.isClosed());";
});
app.endUndoGroup();
}
function tracePath(){
var undoGroup = localize("$$$/AE/Script/CreatePathNulls/CreatePathTracerNull=Create Path Tracer Null");
app.beginUndoGroup(undoGroup);
var sliderName = localize("$$$/AE/Script/CreatePathNulls/TracerTiming=Tracer Timing");
var checkboxName = localize("$$$/AE/Script/CreatePathNulls/LoopTracer=Loop Tracer");
forEachPath(function(comp,selectedLayer,path){
var pathHierarchy = [];
var pathPath = getPropPath(path, pathHierarchy);
// Create tracer null
var newNull = createNull(comp);
// Add expression control effects to the null
var nullControl = newNull.property("ADBE Effect Parade").addProperty("Pseudo/ADBE Trace Path");
nullControl.property("Pseudo/ADBE Trace Path-0002").setValue(true);
nullControl.property("Pseudo/ADBE Trace Path-0001").setValuesAtTimes([0,1],[0,100]);
nullControl.property("Pseudo/ADBE Trace Path-0001").expression =
"if(thisProperty.propertyGroup(1)(\"Pseudo/ADBE Trace Path-0002\") == true && thisProperty.numKeys > 1){ \r" +
"thisProperty.loopOut(\"cycle\"); \r" +
"} else { \r" +
"value \r" +
"}";
newNull.position.expression =
"var pathLayer = thisComp.layer(\"" + selectedLayer.name + "\"); \r" +
"var progress = thisLayer.effect(\"Pseudo/ADBE Trace Path\")(\"Pseudo/ADBE Trace Path-0001\")/100; \r" +
"var pathToTrace = pathLayer" + pathPath + "; \r" +
"pathLayer.toComp(pathToTrace.pointOnPath(progress));";
newNull.rotation.expression =
"var pathToTrace = thisComp.layer(\"" + selectedLayer.name + "\")" + pathPath + "; \r" +
"var progress = thisLayer.effect(\"Pseudo/ADBE Trace Path\")(\"Pseudo/ADBE Trace Path-0001\")/100; \r" +
"var pathTan = pathToTrace.tangentOnPath(progress); \r" +
"radiansToDegrees(Math.atan2(pathTan[1],pathTan[0]));";
newNull.name = "Trace " + selectedLayer.name + ": " + path.parentProperty.name + " [" + pathHierarchy.join(".") + "]";
newNull.label = 10;
});
app.endUndoGroup();
}
})(this);

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