OpenLayers 3 circles with a distance-based radius - openlayers-3

I am trying to draw a circle on a map using OpenLayers. I would like to be able to define the radius of the circle in miles. Something like this:
function generateCircleFeature(lat,lng,radius_in_miles) {
//clever stuff goes here
//calculated_radius = some_function_of radius_in_miles
var circle = new ol.geom.Circle(
ol.proj.transform([lng, lat], 'EPSG:4326', 'EPSG:3857'),
calculated_radius
);
var circleFeature = new ol.Feature(circle);
return circleFeature;
}
I've searched and searched for a simple example that actually works, and am going slightly mad. All suggestions welcomed! Thanks :-)

Related

How to fit route bounds using CARTO-Mobile-SDK

i calculate the route betwen two points, and i get the polygon produced by the separation of this two points, i create the polygon in this way
let polygon = NTPolygon(poses: vector, style: NTPolygonStyleBuilder().buildStyle())
so, i am creating a functionality for when the route between this 2 points is to large you can press the button and the map will zoom out and show the bounding box of the route, for that i get the bounding box from the polygon polygon.getBounds() and i am trying to use map.move(toFit: NTMapBounds!, screenBounds: NTScreenBounds!, integerZoom: Bool, durationSeconds: Float) but i dont how to get NTScreenBounds
Any help whit this issue, also any other approach than using map.move is welcome.
Thanks in advance

NTScreenBounds, in this context, is the layout of your NTMapView.
Here's an example from Xamarin.iOS, you should get the gist of it:
public ScreenBounds FindScreenBounds()
{
var min = new ScreenPos(Frame.X, Frame.Y);
var max = new ScreenPos(Frame.Width, Frame.Height);
return new ScreenBounds(min, max);
}

Hot can I get Circle geometry when using ol.interaction.Draw?

I'm drawing a Circle using ol.interaction.Draw.
this.draw = new ol.interaction.Draw({
source: this.vectorSource,
type: 'Circle'
});
this.draw.on('drawend', function( evt ){
// evt.feature have no geometry !!!
}
But How can I get the Circle geometry or anything that tell me how to draw same circle again?
OL3.0 you can create/edit Features, but not Circles... http://openlayers.org/en/v3.0.0/examples/draw-and-modify-features.html
OL3.5 you can create circles, but you can't edit .... http://openlayers.org/en/v3.5.0/examples/draw-features.html
OL_Latest you can't edit circles too: http://openlayers.org/en/latest/examples/draw-and-modify-features.html
I would be happy if I could reproduce the same circle later.

To get the center and radius of the circle feature drawn use the below code
this.draw.on('drawend', function( evt ){
var geometry = evt.feature.getGeometry();
var radius = geometry.getRadius();
var center = geometry.getCenter();
// .... your code
});
Since a circle is drawn the Geometry type would be of type ol.geom.Circle.
Using this Geometry object you can get the radius and center using getRadius() and getCenter() method. For more information about ol.geom.Circle go through this link.
http://openlayers.org/en/latest/apidoc/ol.geom.Circle.html

Almost there!
I'm now able to reproduce the "circle" by adding a geometry function to the draw intaraction.
var geometryFunction = ol.interaction.Draw.createRegularPolygon(90);
this.draw = new ol.interaction.Draw({
source: this.vectorSource,
type: 'Circle',
geometryFunction: geometryFunction,
});
this will generate geometries to the feature so I can store it and load it again later, but it is not a real circle, it is just composed by a 90 points polygon. so I can't edit it as a circle.
Some idea to get the radius of this geometry?
{"type":"Feature","geometry":{"type":"Polygon","coordinates":[[[-4804935.286197088,-2605909.2147242804],[-4804836.58537814,-2605831.0293000625],[-4804743.578928918,-2605746.149310523],[-4804656.719967494,-2605654.988282439],[-4804576.431661996,-2605557.9903431754],[-4804503.105168979,-2605455.6280569425],[-4804437.097727745,-2605348.4001225093],[-4804378.730919913,-2605236.8289435934],[-4804328.289102704,-2605121.458083764],[-4804286.018023582,-2605002.849618253],[-4804252.123622994,-2604881.581395582],[-4804226.771031053,-2604758.244222341],[-4804210.083763039,-2604633.4389848416],[-4804202.143117644,-2604507.773721655],[-4804202.987780893,-2604381.8606613115],[-4804212.613637674,-2604256.3132395847],[-4804230.973791778,-2604131.7431108924],[-4804257.978794381,-2604008.757168381],[-4804293.497079825,-2603887.954587199],[-4804337.355606593,-2603769.923905379],[-4804389.340700352,-2603655.2401565393],[-4804449.199094949,-2603544.462068375],[-4804516.639166305,-2603438.1293405974],[-4804591.332353169,-2603336.7600155673],[-4804672.914757844,-2603240.8479544464],[-4804760.988919055,-2603150.860431155],[-4804855.125748342,-2603067.2358558625],[-4804954.866620535,-2602990.3816390927],[-4805059.72560813,-2602920.672206864],[-4805169.19184868,-2602858.4471765244],[-4805282.732033666,-2602804.009702166],[-4805399.793006718,-2602757.6249976917],[-4805519.804458544,-2602719.5190447196],[-4805642.1817054115,-2602689.8774916218],[-4805766.328537677,-2602668.8447490656],[-4805891.640124453,-2602656.5232864586],[-4806017.505960285,-2602652.973132728],[-4806143.312839472,-2602658.211583866],[-4806268.447843544,-2602672.213118665],[-4806392.301327342,-2602694.909523055],[-4806514.269889141,-2602726.1902224356],[-4806633.759310369,-2602765.902820383],[-4806750.187450577,-2602813.8538411125],[-4806862.987083566,-2602869.809672071],[-4806971.608660867,-2602933.4977020747],[-4807075.522989073,-2603004.607649443],[-4807174.22380802,-2603082.793073661],[-4807267.230257243,-2603167.6730632004],[-4807354.089218667,-2603258.834091285],[-4807434.3775241645,-2603355.8320305482],[-4807507.704017182,-2603458.194316781],[-4807573.711458416,-2603565.4222512143],[-4807632.078266247,-2603676.99343013],[-4807682.520083456,-2603792.3642899594],[-4807724.791162578,-2603910.972755471],[-4807758.685563167,-2604032.240978142],[-4807784.038155108,-2604155.5781513825],[-4807800.725423122,-2604280.383388882],[-4807808.666068517,-2604406.0486520687],[-4807807.821405267,-2604531.961712412],[-4807798.195548487,-2604657.509134139],[-4807779.8353943825,-2604782.0792628312],[-4807752.83039178,-2604905.0652053426],[-4807717.312106336,-2605025.867786525],[-4807673.453579567,-2605143.8984683445],[-4807621.468485809,-2605258.5822171844],[-4807561.610091211,-2605369.3603053484],[-4807494.170019856,-2605475.693033126],[-4807419.4768329915,-2605577.0623581563],[-4807337.8944283165,-2605672.974419277],[-4807249.8202671055,-2605762.9619425684],[-4807155.683437819,-2605846.586517861],[-4807055.9425656255,-2605923.440734631],[-4806951.083578031,-2605993.1501668594],[-4806841.61733748,-2606055.375197199],[-4806728.077152494,-2606109.8126715575],[-4806611.016179442,-2606156.197376032],[-4806491.004727617,-2606194.303329004],[-4806368.627480749,-2606223.944882102],[-4806244.480648483,-2606244.977624658],[-4806119.169061707,-2606257.299087265],[-4805993.303225876,-2606260.8492409955],[-4805867.496346689,-2606255.610789858],[-4805742.361342616,-2606241.6092550587],[-4805618.507858818,-2606218.9128506687],[-4805496.539297019,-2606187.632151288],[-4805377.049875791,-2606147.9195533404],[-4805260.621735584,-2606099.968532611],[-4805147.822102594,-2606044.0127016525],[-4805039.200525293,-2605980.324671649],[-4804935.286197088,-2605909.2147242804]]]},"properties": null}
The Polygon's centroid can be the circle center I think.... the distance of this centroid to any point in the border can be the radius.... I don't know how to get this using JS.
To take the center:
this.draw.on('drawend', function( evt ){
var aa = evt.feature.getGeometry().getExtent();
var oo = ol.extent.getCenter(aa);
console.log( oo );
});
Now I must find a way to take the radius.

openlayers-3 precompose, how to do layer clipping with a rectangular geometry

I'm trying to make a simple app doing something similar to the Layer Spy Example, but instead of a circle flowing the mouse pointer, I would like to do the clipping based on a rectangle which is always centered in the map.
(preferably with "fixed" size" i.e. changes "extent" when zooming)
Any help appreciated
Thanks
Frode

You can do it like in the example that you are referring to. But instead of context.arc() use context.rect() with a fixed position to clip the layer. Something like:
imagery.on('precompose', function(event) {
var ctx = event.context;
var pixelRatio = event.frameState.pixelRatio;
ctx.save();
ctx.beginPath();
var x = ctx.canvas.width / 2 - 100;
var y = ctx.canvas.height / 2 - 100;
ctx.rect(x, y, 100, 100);
ctx.clip();
});
http://jsfiddle.net/eo1c1x78/

How to interactively Draw a Circle in openlayers-3

I'am intersted in a fuctionality, that was present in openlayers-2, but absent at the moment in 3rd installment - interactive circle drawing.
As you can see in example here: http://openlayers.org/en/v3.0.0/examples/draw-and-modify-features.html
There's no available option for Circle. Even though comment states, that there should be available all of #type {ol.geom.GeometryType}, circle dowsen't work. Tried it myself with this piece of code:
function addInteraction(type) {
draw = new ol.interaction.Draw({
features: featureOverlay.getFeatures(),
type: /** #type {ol.geom.GeometryType} */ 'Circle'
});
map.addInteraction(draw);
}
Is there any native\patch\hack solutions present?

This feature has now been added in version 3.5.0, with an example here: http://openlayers.org/en/v3.5.0/examples/draw-features.html
It works exactly like you guessed, that is
draw = new ol.interaction.Draw({
features: featureOverlay.getFeatures(),
type: 'Circle'
});
map.addInteraction(draw);

I had nearly the same problem. The Question is if you want to add just a circle for styling reasons or you need it as a polygon? When you try too achieve a polygon you can easyily use the Poylgon.based circular function. As you can see in the source code below you only need the sphere. For example ol.sphere.WGS84. The center point and the radius. The optional input defines the number of points. which are used to define the circle.
ol.geom.Polygon.circular = function(sphere, center, radius, opt_n) {
var n = goog.isDef(opt_n) ? opt_n : 32;
/** #type {Array.<number>} */
var flatCoordinates = [];
var i;
for (i = 0; i < n; ++i) {
goog.array.extend(
flatCoordinates, sphere.offset(center, radius, 2 * Math.PI * i / n));
}
flatCoordinates.push(flatCoordinates[0], flatCoordinates[1]);
var polygon = new ol.geom.Polygon(null);
polygon.setFlatCoordinates(
ol.geom.GeometryLayout.XY, flatCoordinates, [flatCoordinates.length]);
return polygon;
};
It is even Api Stable so you can access it from outside. IN my case i created an own control which extended the draw feature. Hope i was able to help you.

Center of rotation for cc.RotateBy applied on a cc.DrawNode in cocos2d-js

I made a drawNode to draw primitive using this code:
var.drawNode = cc.DrawNode.create();
drawNode.drawSegment(this.pos, cc.p(this.pos.x + this.length * Math.sin(this.rotation), this.pos.y + this.length * Math.cos(this.rotation)), STICK_THICKESS, cc.color(255,255,0,255));
It basically draws a line from this.pos to another point.
Now I want to rotate the line around this.pos, so I thought I just need to simply add this:
drawNode.setAnchorPoint(this.pos);
var rotate = cc.RotateBy.create(2, 360);
drawNode.runAction(rotate);
But it's still rotating around some random point.

Ugly but working method:
drawNode.setContentSize(1, 1);
drawNode.setAnchorPoint(this.pos);
drawNode.setPosition(this.pos);
var rotate = cc.RotateBy.create(2, 360);
drawNode.runAction(rotate);
BTW create methods are deprecated in Cocos2d-html5 3.0+. Use cc.rotateBy() instead of cc.RotateBy.Create(), new cc.DrawNode() instead of cc.DrawNode.create()

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