Setting Constraints in Adobe Illustrator [closed] - constraints

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Is there a way to put restrictions on objects in Adobe Illustrator?
I want to place multiple objects to a POI. The objects themselves should always look at the POI. In addition, the orientation of the objects shall be updated, when the POI is moved.
Is there a way to define this type of logic in Adobe Illustrator?
Thanks for your help!
Jan

Answer 1

You can write a script to do that.
One issue is how to determine which of the objects is the correct one.
As a quick hacky solution is to use a naming convention: say the POI object contains the characters "POI" in it's name.
Once you've got the POI object it's just a matter of using atan2 to get the from every other object to the POI:
var dx = POI.x - obj.x;
var dy = POI.y - obj.y;
var angle = atan2(dy,dx);
Here's a quick script:
/*
* Rotates a bunch of selected items towards a chosen target
*
* Usage: select at least 2 objects and mark the "look at" target by having POI in the name of the item
*/
#target illustrator
var d = app.activeDocument;//current document
var s = d.selection;//current selection
var hasDocCoords = app.coordinateSystem == CoordinateSystem.DOCUMENTCOORDINATESYSTEM;
var poi = getPOI(s);//get an object that contains 'poi'/'POI' in the name
if(s.length > 1 && poi != undefined){//if there are at least 2 objects and one's a POI
var lookAt = getPos(poi);//get the position to look at
for(var i = 0 ; i < s.length; i++){//for each object
if(s[i] != poi){//that isn't the poi
var pos = getPos(s[i]);//get the position
//get the angle using atan2 and the difference vector between the two positions(current object and poi)
var angle = Math.atan2(pos[1]-lookAt[1],pos[0]-lookAt[0]);
//check if there's a rotation applied, if so, remove it first
if(s[i].tags.length > 0){
if(s[i].tags[0].name == "BBAccumRotation"){
s[i].rotate(s[i].tags[0].value* -57.2957795);//reverse rotate
s[i].tags[0].remove();
}
}
//if it doesn't have a rotation tag, add one so it can be removed when the script is reapplied
if(s[i].tags.length == 0){
var t = s[i].tags.add();
t.name = "BBAccumRotation";
t.value = angle;
}
s[i].rotate(angle * 57.2957795);//finally convert radians to degrees and apply the rotation
}
}
app.redraw();
}
function getPOI(s){//find POI in selection
for(var i = 0 ; i < s.length; i++)
if (s[i].name.toUpperCase().indexOf("POI") >= 0) return s[i];
}
function getPos(o){
var pos = hasDocCoords ? d.convertCoordinate (o.position, CoordinateSystem.DOCUMENTCOORDINATESYSTEM, CoordinateSystem.ARTBOARDCOORDINATESYSTEM) : o.position;
pos[0] += o.width;//offset to centre of object
pos[1] -= o.height;
return pos;
}
You can save it as something like Look At POI.jsx in the right location (ILLUSTRATOR_INSTALL_DIR/Presets/LOCALE/Scripts) so it becomes accessible via File > Scripts > Look At POI
To use it, select at least 2 objects make sure one contains POI in the name.
Here's a quick preview:
Note that the triangles are symbols. This makes it easy to adjust rotation (as you can see in the Symbols panel) globally if it needs tweaking. Another way is to add an offset to the angle in the script, but this feels flexible enough :)
A non scripted version might using the Symbol Spinner Tool but it's a slow and not very precise process: