I am trying out paper.js and I've made a few circles:
var circle = new Shape.Circle({
center: [100,100],
radius: 50,
strokeColor: 'black',
strokeWidth: 2
});
This draws a circle with center [100,100] (which could also be a point: Point({x:100, y:100});) and radius 50. This is great, this is a circle.
If I want to get the radius of a circle, I can do this:
circle.radius; // returns 50
But I don't know how to get the center back again. Part of the reason I guess is that Shape.Circle returns a Shape object, which does not have a center parameter (documentation here), but surely I can get this point back somehow. Does anyone know how?
Since circles are centred on the position they're created at, you can get the position (as a Point) and the x and y values from that:
var circle = new Shape.Circle({
center: [100,100],
radius: 50,
strokeColor: 'black',
strokeWidth: 2
});
console.log(circle.position.x, circle.position.y); //100 100
From http://paperjs.org/reference/shape/#position
While the circle object does not have a center property, if you read the docs properly you will find that it does have a bounds property.
In graphics, a "bound" is the rectangle that fully contains your object. So for a circle, the bounds will be a rectangle that touches the circle on the left, right, top and bottom. Therefore the center of the bound is the center of the circle (note: this is not always true for all objects depending on your definition of "center").
Paper.js will give you:
circle.bounds.x
circle.bounds.width
circle.bounds.y
circle.bounds.height
Therefore the center of the circle is:
var centerX = circle.bounds.x + circle.bounds.width/2;
var centerY = circle.bounds.y + circle.bounds.height/2;
Note: You will have to try this out yourself as I have zero experience with paper.js. I just read the docs
Use :
circle.center[0] and circle.center[1]
cause its an array
<script>
var circle = {
center: [100,100],
radius: 50,
strokeColor: 'black',
strokeWidth: 2
};
console.log(circle.center[0]);
</script>
Update:
Sorry, I haven't read your question properly.
You can use circle.position to get the position of center.
Related
I'm trying to set the pivot point of a group that contains a raster image to the center of the screen to no avail.
Please see my current code here: condesandbox example
Any help will be much appreciated
Based on your code example, I guess that you just have to set the position of your raster to be the view center and its pivot point will automatically be the same by default.
Here is a sketch demonstrating a possible solution.
// Create the raster.
const raster = new Raster({
source: 'http://assets.paperjs.org/images/marilyn.jpg',
// When image is loaded...
onLoad: () => {
// ...place it at center.
raster.position = view.center;
}
});
// Include raster in a group.
const group = new Group(raster);
// Mark center with a circle.
new Path.Circle({
center: view.center,
radius: 10,
fillColor: 'blue'
});
// Scale the group (the pivot point is bounds center by default).
group.scale(0.5);
The examples shown in here show how to move an object along the path in Paperjs but how do I rotate them correctly along the path?
In the examples shown on the link above, people suggested by using a circle as an example. But once changed to a rectangle new Path.Rectangle(new Point(20,20), new Size(20,20)); you can see that it moves along the path but does not actually rotate in the direction of the path.
How do I calculate the rotation and set it to my object?
In order to calculate the rotation, you need to know the tangent vector to the path at the position of your rectangle.
This can be retrieved with path.getTangentAt(offset) method.
Then, an easy way to animate the rotation of an item is to set item.applyMatrix to false and then animate the item.rotation property on each frame.
Here is a sketch demonstrating the solution.
// Create the rectangle to animate along the path.
// Note that matrix is not applied, this will allow us to easily animate its
// rotation.
var rectangle = new Path.Rectangle({
point: view.center,
size: new Size(100, 200),
strokeColor: 'orange',
applyMatrix: false
});
// Create the path along which the rectangle will be animated.
var path = new Path.Circle({
center: view.center,
radius: 250,
strokeColor: 'blue'
});
// On each frame...
function onFrame(event) {
// ...calculate the time of the animation between 0 and 1...
var slowness = 400;
var time = event.count % slowness / slowness;
// ...and move the rectangle.
updateRectangle(time);
}
function updateRectangle(time) {
// Calculate the offset relatively to the path length.
var offset = time * path.length;
// Get point to position the rectangle.
var point = path.getPointAt(offset);
// Get tangent vector at this point.
var tangent = path.getTangentAt(offset);
// Move rectangle.
rectangle.position = point;
// Rotate rectangle.
rectangle.rotation = tangent.angle;
}
I have a project which consist in visualizing the exchange of data between points on a map.
I'm using Leaflet to draw polylines from coordinates in a GeoJson file and Leaflet.polylineDecorator (https://github.com/bbecquet/Leaflet.PolylineDecorator) to put an animated arrow on the polyline.
The thing is that I need to visualize the stream in both directions. I started by adding to my Geojson file polylines in the other direction but the issue is when I zoom out, the two polylines are stacked.
So I found Leaflet.polylineOffset (https://github.com/bbecquet/Leaflet.PolylineOffset) which allows to create an another polyline just by setting the offset option.
I thought, i just had to do the same to put the animated arrow on it but when i'm doing it, the animation is affected to the original polyline. In fact, the offset polyline keeps the coordinates from the original one.
I wanted to know if there is a way to apply this animation to the offset polyline.
Here is my code:
d3.json("data/trajetsFibreDCSigma.json",function (data){ // getting polylines' data from a json file to add them on the map
L.geoJson(data, {
style: function(feature){return {color : feature.properties.stroke,opacity: 1};}, // setting the style of the polylines
onEachFeature: function(feature){
// getting the coordinates of the polyline from the json file
var latlng = feature.geometry.coordinates;
var size = feature.geometry.coordinates.length;
var buffer;
// reversing the order of latitude and longitude in the array because a L.latLng object needs the latitude first and I have the opposite in my json file
for (i=0;i<size;i++)
{
buffer = latlng[i][0];
latlng[i][0] = latlng[i][1];
latlng[i][1] = buffer;
}
var polylineOffset = L.polyline(latlng,{offset: 5,color: 'blue',opacity: 1}).addTo(map); // putting an offset to the polyline
addArrow(latlng,feature);
addArrow(polylineOffset,feature);
}
}).addTo(map);
});
function addArrow(polyline,feature){ // function to add an arrow on the map
var arrowHead = L.polylineDecorator(polyline).addTo(map); // creating an arrow which will be put on the polyline
var arrowOffset = 0;
window.setInterval(function() { // creating an animation for the arrow to cross the polyline
arrowHead.setPatterns([
{offset: arrowOffset+'%', repeat: 0, symbol: L.Symbol.arrowHead({pixelSize: 10, polygon: false,
pathOptions: {stroke: true,color: feature.properties.stroke,opacity: 1}})}
]);
if(++arrowOffset > 100)
arrowOffset = 0;
}, 100);
}
(If I'm just calling addArrow with the offset polyline, it will pop on the original one).
I found a solution to get the offset polyline's coordinates.
The PolylineOffset plugin has a function which returns the offset coordinates.
You can use it like this:
var pts = L.PolylineOffset.offsetLatLngs(latlng,10,map); // getting the coordinates from the offset polyline
where latlng is the array of the original coordinates
; 10 is the offset
; map is your leaflet map
I want to create a hole in my Javascript Google API V3, so i follow Beginning Google Map API V3. But the code is rendering the whole area. Here is my Javascript code.
(function() {
window.onload = function() {
// Creating a map
var options = {
zoom: 6,
center: new google.maps.LatLng(36.5, -79.8),
mapTypeId: google.maps.MapTypeId.ROADMAP
};
var map = new google.maps.Map(document.getElementById('map'), options);
// Creating an array with the points for the outer polygon
var polyOuter = [
new google.maps.LatLng(37.303, -81.256),
new google.maps.LatLng(37.303, -78.333),
new google.maps.LatLng(35.392, -78.333),
new google.maps.LatLng(35.392, -81.256)
];
// Creating an array with the points for the inner polygon
var polyInner = [
new google.maps.LatLng(36.705, -80.459),
new google.maps.LatLng(36.705, -79),
new google.maps.LatLng(35.9, -79),
new google.maps.LatLng(35.9, -80.459)
];
var points = [polyOuter, polyInner];
// Creating the polygon
var polygon = new google.maps.Polygon
({
paths: points,
map: map,
strokeColor: '#ff0000',
strokeOpacity: 0.6,
strokeWeight: 3,
fillColor: '#FF0000',
fillOpacity: 0.35
});
};
})();
One of the paths has to be reverted so polygons are drawn in different directions, for example:
var polyInner = [
new google.maps.LatLng(35.9, -80.459),
new google.maps.LatLng(35.9, -79),
new google.maps.LatLng(36.705, -79),
new google.maps.LatLng(36.705, -80.459)
];
My assumption is that the reason is how SVG or canvas render closed loops. If I am not wrong explanation lies in nonzero winding rule. See explanation at wikipedia.
Outer path is drawn clockwise, inner path is drawn counter-clockwise.
Set a counter to zero. Pick a point in object area and draw a line in direction out of object space. If the line cross clockwise path, add one. If the line cross counter-clockwise path segment, subtract one. If the final result for selected point is non-zero, the browser fills the area. If the final result is zero, the browser does not fill it.
So, if you pick up point in the 'hole', the result will be zero and area will not be filled.
have a web page which displays weather charts from many sources. You pick your source and outlines of the charts appear on a Google Map. (See http://www.geoffschultz.org/weather_map.php Weather Charts/GMDSS/Forecasts - should draw 3 polygons) Up until now all of the charts have been rectangular, but I just came across the need for non-rectangular charts. I had coded the js with this in mind, but I have been baffled because only the last polygon drawn is displayed. Is there something that I'm missing with regards to multiple polygons?
The code is very simple. It gets an array of bounding box coordinates. For simple rectangles the array element looks like "-31,-32|2,25" and for polygons it just has more coordinates separated by "|". If there are 2 coordinates, I draw a rectangle, otherwise I draw a polygon, closing it with the 1st point.
What am I doing wrong as it works great for rectangles?
-- Geoff
for (i in bb[selValue])
{
bb_lat_long = bb[selValue][i]["bb_lat_long"].split("|");
if (bb_lat_long.length == 2) //Rectangle
{
lat_long = bb_lat_long[0].split(",");
sw = new google.maps.LatLng(lat_long[0], lat_long[1]);
lat_long = bb_lat_long[1].split(",");
ne = new google.maps.LatLng(lat_long[0], lat_long[1]);
bounds = new google.maps.LatLngBounds(sw, ne);
bounding_box = new google.maps.Rectangle({map: map, bounds: bounds, fillOpacity: 0.05, strokeWeight: 1});
}
else // polygon
{
poly_lat_long.length = 0;
for (j = 0; j < bb_lat_long.length; j++)
{
lat_long = bb_lat_long[j].split(",");
poly_lat_long.push(new google.maps.LatLng(lat_long[0], lat_long[1]));
}
lat_long = bb_lat_long[0].split(",");
poly_lat_long.push(new google.maps.LatLng(lat_long[0], lat_long[1])); // close polygon with 1st point
bounding_box = new google.maps.Polygon({map: map, paths: poly_lat_long, fillOpacity: 0.05, strokeWeight: 1});
}
}
My suspicion is that it has to do with re-using the path in the new polygons (you are ending up with multiple polygons, the just all are the same, perhaps if you declare poly_lat_long locally (with var), or make a createPolygon function that would get function closure on the path.
I have seen this behavior before when clearing the path array using poly_lat_long.length = 0;
rather than creating a new array (poly_lat_long = []).
Thread from the Google Maps API v3 group discussing similar problem