diff --git a/README.md b/README.md index ad69b1b..273d019 100644 --- a/README.md +++ b/README.md @@ -425,11 +425,11 @@ function y() { The *y*-accessor is invoked for each [node](#simulation_nodes) in the simulation, being passed the *node* and its zero-based *index*. The resulting number is then stored internally, such that the target *y*-coordinate of each node is only recomputed when the force is initialized or when this method is called with a new *y*, and not on every application of the force. -# d3.forceRadial(radius[, x][, y]) [<>](https://github.com/d3/d3-force/blob/master/src/radial.js "Source") +# d3.forceRadial(radius[, x][, y][, angle]) [<>](https://github.com/d3/d3-force/blob/master/src/radial.js "Source") [Radial Force](https://bl.ocks.org/mbostock/cd98bf52e9067e26945edd95e8cf6ef9) -Creates a new positioning force towards a circle of the specified [*radius*](#radial_radius) centered at ⟨[*x*](#radial_x),[*y*](#radial_y)⟩. If *x* and *y* are not specified, they default to ⟨0,0⟩. +Creates a new positioning force towards a circle of the specified [*radius*](#radial_radius) centered at ⟨[*x*](#radial_x),[*y*](#radial_y)⟩, and with a preferred [*angle*](#radial_angle). If *x* and *y* are not specified, they default to ⟨0,0⟩. If *radius* or *angle* are not specified (or null), they are ignored. # radial.strength([strength]) [<>](https://github.com/d3/d3-force/blob/master/src/radial.js "Source") @@ -447,7 +447,7 @@ The strength accessor is invoked for each [node](#simulation_nodes) in the simul # radial.radius([radius]) [<>](https://github.com/d3/d3-force/blob/master/src/radial.js "Source") -If *radius* is specified, sets the circle *radius* to the specified number or function, re-evaluates the *radius* accessor for each node, and returns this force. If *radius* is not specified, returns the current *radius* accessor. +If *radius* is specified, sets the circle *radius* to the specified number or function, re-evaluates the *radius* accessor for each node, and returns this force. If *radius* is not specified, returns the current *radius* accessor. If *angle* is null, the force ignores the radius (see [*radial*.angle](#radial_angle)). The *radius* accessor is invoked for each [node](#simulation_nodes) in the simulation, being passed the *node* and its zero-based *index*. The resulting number is then stored internally, such that the target radius of each node is only recomputed when the force is initialized or when this method is called with a new *radius*, and not on every application of the force. @@ -475,3 +475,9 @@ function y() { The *y*-accessor is invoked for each [node](#simulation_nodes) in the simulation, being passed the *node* and its zero-based *index*. The resulting number is then stored internally, such that the target *y*-coordinate of each node is only recomputed when the force is initialized or when this method is called with a new *y*, and not on every application of the force. +# radial.angle([angle]) [<>](https://github.com/d3/d3-force/blob/master/src/radial.js "Source") + +If *angle* is specified, sets the preferred *angle* to the specified number or function, re-evaluates the *angle* accessor for each node, and returns this force. If *angle* is not specified, returns the current *angle* accessor. If *angle* is null, the force ignores the preferred angle. + +The *angle* accessor is invoked for each [node](#simulation_nodes) in the simulation, being passed the *node* and its zero-based *index*. The resulting number is then stored internally, such that the target angle of each node is only recomputed when the force is initialized or when this method is called with a new *angle*, and not on every application of the force. + diff --git a/src/math.js b/src/math.js new file mode 100644 index 0000000..d38afca --- /dev/null +++ b/src/math.js @@ -0,0 +1,2 @@ +export var pi = Math.PI; +export var radians = pi / 180; diff --git a/src/radial.js b/src/radial.js index dbf2661..3fe3ff1 100644 --- a/src/radial.js +++ b/src/radial.js @@ -1,26 +1,52 @@ import constant from "./constant.js"; +import {radians} from "./math.js"; -export default function(radius, x, y) { +function value(x) { + if (typeof x === "function") return x; + if (x === null || x === undefined || isNaN(x = +x)) return; + return constant(x); +} + +export default function(radius, x, y, angle) { var nodes, strength = constant(0.1), strengths, - radiuses, + radii, xs, - ys; + ys, + angles; - if (typeof radius !== "function") radius = constant(+radius); - if (typeof x !== "function") x = constant(x == null ? 0 : +x); - if (typeof y !== "function") y = constant(y == null ? 0 : +y); + radius = value(radius); + x = value(x) || constant(0); + y = value(y) || constant(0); + angle = value(angle); function force(alpha) { for (var i = 0, n = nodes.length; i < n; ++i) { var node = nodes[i], dx = node.x - xs[i] || 1e-6, dy = node.y - ys[i] || 1e-6, - r = Math.sqrt(dx * dx + dy * dy), - k = (radiuses[i] - r) * strengths[i] * alpha / r; - node.vx += dx * k; - node.vy += dy * k; + r = Math.sqrt(dx * dx + dy * dy); + + if (radius) { + var k = ((radii[i] - r) * strengths[i] * alpha) / r; + node.vx += dx * k; + node.vy += dy * k; + } + + if (angle) { + var a = Math.atan2(dy, dx), + diff = angles[i] - a, + q = r * Math.sin(diff) * (strengths[i] * alpha); + + // the factor below augments the "unease" for points that are opposite + // the correct direction: in that case, though sin(diff) is small, + // tan(diff/2) is very high + q *= Math.hypot(1, Math.tan(diff / 2)); + + node.vx += -q * Math.sin(a); + node.vy += q * Math.cos(a); + } } } @@ -28,14 +54,16 @@ export default function(radius, x, y) { if (!nodes) return; var i, n = nodes.length; strengths = new Array(n); - radiuses = new Array(n); + radii = new Array(n); xs = new Array(n); ys = new Array(n); + angles = new Array(n); for (i = 0; i < n; ++i) { - radiuses[i] = +radius(nodes[i], i, nodes); + if (radius) radii[i] = +radius(nodes[i], i, nodes); xs[i] = +x(nodes[i], i, nodes); ys[i] = +y(nodes[i], i, nodes); - strengths[i] = isNaN(radiuses[i]) ? 0 : +strength(nodes[i], i, nodes); + if (angle) angles[i] = +angle(nodes[i], i, nodes) * radians; + strengths[i] = isNaN(radii[i]) ? 0 : +strength(nodes[i], i, nodes); } } @@ -44,19 +72,23 @@ export default function(radius, x, y) { }; force.strength = function(_) { - return arguments.length ? (strength = typeof _ === "function" ? _ : constant(+_), initialize(), force) : strength; + return arguments.length ? (strength = value(_) || constant(1), initialize(), force) : strength; }; force.radius = function(_) { - return arguments.length ? (radius = typeof _ === "function" ? _ : constant(+_), initialize(), force) : radius; + return arguments.length ? (radius = value(_), initialize(), force) : radius; }; force.x = function(_) { - return arguments.length ? (x = typeof _ === "function" ? _ : constant(+_), initialize(), force) : x; + return arguments.length ? (x = value(_) || constant(0), initialize(), force) : x; }; force.y = function(_) { - return arguments.length ? (y = typeof _ === "function" ? _ : constant(+_), initialize(), force) : y; + return arguments.length ? (y = value(_) || constant(0), initialize(), force) : y; + }; + +force.angle = function(_) { + return arguments.length ? (angle = value(_), initialize(), force) : y; }; return force;