Draw not only 1 but multiple arrows

[Kai-Uwe Bracklo]

Hi,

I'm new to Paper.js and I try to figure out how to modify the vector geometry example so that I can draw multiple arrows. When trying to draw the second one, the first will be removed.

I used this code from the vector geometry turorial.

Can someone explain how to not remove the first arrow when drawing another?

Thanks!

Here the code (from the vector geometry tutorial):

you will find it on this page at the bottom. http://paperjs.org/tutorials/geometry/vector-geometry/

var values = {
fixLength: false,
fixAngle: false,
showCircle: false,
showAngleLength: false,
showCoordinates: false
};

var vectorStart, vector, vectorPrevious;
var vectorItem, items, dashedItems;

function processVector(event, drag) {
vector = event.point - vectorStart;
if (vectorPrevious) {
if (values.fixLength && values.fixAngle) {
vector = vectorPrevious;
} else if (values.fixLength) {
vector.length = vectorPrevious.length;
} else if (values.fixAngle) {
vector = vector.project(vectorPrevious);
}
}
drawVector(drag);
}

function drawVector(drag) {
if (items) {
for (var i = 0, l = items.length; i < l; i++) {
items[i].remove();
}
}
if (vectorItem)
vectorItem.remove();
items = [];
var arrowVector = vector.normalize(15);
var end = vectorStart + vector;
vectorItem = new Group([
new Path([vectorStart, end]),
new Path([
end + arrowVector.rotate(135),
end,
end + arrowVector.rotate(-135)
])
]);
vectorItem.strokeWidth = 5;
vectorItem.strokeColor = '#e4141b';
// Display:
dashedItems = [];
// Draw Circle
if (values.showCircle) {
dashedItems.push(new Path.Circle({
center: vectorStart,
radius: vector.length
}));
}
// Draw Labels
if (values.showAngleLength) {
drawAngle(vectorStart, vector, !drag);
if (!drag)
drawLength(vectorStart, end, vector.angle < 0 ? -1 : 1, true);
}
var quadrant = vector.quadrant;
if (values.showCoordinates && !drag) {
drawLength(vectorStart, vectorStart + [vector.x, 0],
[1, 3].indexOf(quadrant) != -1 ? -1 : 1, true, vector.x, 'x: ');
drawLength(vectorStart, vectorStart + [0, vector.y],
[1, 3].indexOf(quadrant) != -1 ? 1 : -1, true, vector.y, 'y: ');
}
for (var i = 0, l = dashedItems.length; i < l; i++) {
var item = dashedItems[i];
item.strokeColor = 'black';
item.dashArray = [1, 2];
items.push(item);
}
// Update palette
values.x = vector.x;
values.y = vector.y;
values.length = vector.length;
values.angle = vector.angle;
}

function drawAngle(center, vector, label) {
var radius = 25, threshold = 10;
if (vector.length < radius + threshold || Math.abs(vector.angle) < 15)
return;
var from = new Point(radius, 0);
var through = from.rotate(vector.angle / 2);
var to = from.rotate(vector.angle);
var end = center + to;
dashedItems.push(new Path.Line(center,
center + new Point(radius + threshold, 0)));
dashedItems.push(new Path.Arc(center + from, center + through, end));
var arrowVector = to.normalize(7.5).rotate(vector.angle < 0 ? -90 : 90);
dashedItems.push(new Path([
end + arrowVector.rotate(135),
end,
end + arrowVector.rotate(-135)
]));
if (label) {
// Angle Label
var text = new PointText(center
+ through.normalize(radius + 10) + new Point(0, 3));
text.content = Math.floor(vector.angle * 100) / 100 + '°';
text.fillColor = 'black';
items.push(text);
}
}

function drawLength(from, to, sign, label, value, prefix) {
var lengthSize = 5;
if ((to - from).length < lengthSize * 4)
return;
var vector = to - from;
var awayVector = vector.normalize(lengthSize).rotate(90 * sign);
var upVector = vector.normalize(lengthSize).rotate(45 * sign);
var downVector = upVector.rotate(-90 * sign);
var lengthVector = vector.normalize(
vector.length / 2 - lengthSize * Math.sqrt(2));
var line = new Path();
line.add(from + awayVector);
line.lineBy(upVector);
line.lineBy(lengthVector);
line.lineBy(upVector);
var middle = line.lastSegment.point;
line.lineBy(downVector);
line.lineBy(lengthVector);
line.lineBy(downVector);
dashedItems.push(line);
if (label) {
// Length Label
var textAngle = Math.abs(vector.angle) > 90
? textAngle = 180 + vector.angle : vector.angle;
// Label needs to move away by different amounts based on the
// vector's quadrant:
var away = (sign >= 0 ? [1, 4] : [2, 3]).indexOf(vector.quadrant) != -1
? 8 : 0;
value = value || vector.length;
var text = new PointText({
point: middle + awayVector.normalize(away + lengthSize),
content: (prefix || '') + Math.floor(value * 1000) / 1000,
fillColor: 'black',
justification: 'center'
});
text.rotate(textAngle);
items.push(text);
}
}

var dashItem;

function onMouseDown(event) {
var end = vectorStart + vector;
var create = false;
if (event.modifiers.shift && vectorItem) {
vectorStart = end;
create = true;
} else if (vector && (event.modifiers.option
|| end && end.getDistance(event.point) < 10)) {
create = false;
} else {
vectorStart = event.point;
}
if (create) {
dashItem = vectorItem;
vectorItem = null;
}
processVector(event, true);
// document.redraw();
}

function onMouseDrag(event) {
if (!event.modifiers.shift && values.fixLength && values.fixAngle)
vectorStart = event.point;
processVector(event, event.modifiers.shift);
}

function onMouseUp(event) {
processVector(event, false);
if (dashItem) {
dashItem.dashArray = [1, 2];
dashItem = null;
}
vectorPrevious = vector;
}