After Effects│コンポ内のエクスプレッションをベイクするスクリプト

(function () {
    var comp = app.project && app.project.activeItem;
    if (!(comp instanceof CompItem)) { alert("Open a composition."); return; }
    var targets = [], plans = [], times = [], frame = comp.frameDuration, i, j;
    function dimensions(type) {
        if (type === PropertyValueType.OneD) { return 1; }
        if (type === PropertyValueType.TwoD || type === PropertyValueType.TwoD_SPATIAL) { return 2; }
        if (type === PropertyValueType.ThreeD || type === PropertyValueType.ThreeD_SPATIAL) { return 3; }
        if (type === PropertyValueType.COLOR) { return 4; }
        return 0;
    }
    function collect(group, locked) {
        for (var k = 1; k <= group.numProperties; k++) {
            var prop = group.property(k);
            if (prop.propertyType !== PropertyType.PROPERTY) { collect(prop, locked); continue; }
            if (!prop.canSetExpression || !prop.expressionEnabled) { continue; }
            if (locked || prop.numKeys !== 0 || prop.expressionError || !dimensions(prop.propertyValueType)) {
                throw new Error("Only unlocked numeric expressions without existing keys are supported.");
            }
            targets.push(prop);
        }
    }
    try {
        if (!isFinite(frame) || frame <= 0 || !isFinite(comp.duration) || comp.duration <= 0) { throw new Error("Invalid duration."); }
        var count = Math.ceil(comp.duration / frame - 0.000001);
        if (count < 1 || count > 3000) { throw new Error("Use 1 to 3000 frames."); }
        for (i = 1; i <= comp.numLayers; i++) { collect(comp.layer(i), comp.layer(i).locked); }
        if (!targets.length || targets.length > 20 || targets.length * count > 20000) { throw new Error("Too many properties or samples, or no target."); }
        for (i = 0; i < count; i++) { times.push(i * frame); }
        // Sample every target before writing keys, including dependent expressions.
        for (i = 0; i < targets.length; i++) {
            var prop = targets[i], values = [], size = dimensions(prop.propertyValueType);
            for (j = 0; j < times.length; j++) {
                var value = prop.valueAtTime(times[j], false), copy;
                if (prop.expressionError) { throw new Error(prop.expressionError); }
                if (size === 1) {
                    if (typeof value !== "number" || !isFinite(value)) { throw new Error("Invalid scalar sample."); }
                    copy = value;
                } else {
                    if (!value || value.length !== size) { throw new Error("Invalid vector sample."); }
                    copy = [];
                    for (var n = 0; n < size; n++) {
                        if (typeof value[n] !== "number" || !isFinite(value[n])) { throw new Error("Invalid vector sample."); }
                        copy.push(value[n]);
                    }
                }
                values.push(copy);
            }
            plans.push({prop:prop, values:values});
        }
    } catch (error) { alert("Nothing changed: " + error.toString()); return; }
    app.beginUndoGroup("Bake numeric expressions at comp frames");
    try {
        for (i = 0; i < plans.length; i++) {
            var plan = plans[i]; plan.prop.setValuesAtTimes(times, plan.values);
            for (j = 1; j <= plan.prop.numKeys; j++) {
                plan.prop.setInterpolationTypeAtKey(j, KeyframeInterpolationType.LINEAR, KeyframeInterpolationType.LINEAR);
            }
            plan.prop.expressionEnabled = false; // Keep the original expression text.
        }
    } catch (error) { alert("Stopped: " + error.toString() + "\nUndo or reopen your practice copy."); }
    finally { app.endUndoGroup(); }
})();