Commit bfce5d5d authored by Daniel Goldbach's avatar Daniel Goldbach
Browse files

Refactor isLeft out of clip-extent into trigonometry

parent e4af0902
......@@ -1176,6 +1176,12 @@ d3 = function() {
function d3_sgn(x) {
return x > 0 ? 1 : x < 0 ? -1 : 0;
}
function d3_isCCWTurn(a, b, c) {
return d3_cross2d(a, b, c) > 0;
}
function d3_cross2d(o, a, b) {
return (a[0] - o[0]) * (b[1] - o[1]) - (a[1] - o[1]) * (b[0] - o[0]);
}
function d3_acos(x) {
return x > 1 ? 0 : x < -1 ? π : Math.acos(x);
}
......@@ -3114,18 +3120,15 @@ d3 = function() {
for (var j = 1, v = polygon[i], m = v.length, a = v[0], b; j < m; ++j) {
b = v[j];
if (a[1] <= y) {
if (b[1] > y && isLeft(a, b, p) > 0) ++wn;
if (b[1] > y && d3_isCCWTurn(a, b, p)) ++wn;
} else {
if (b[1] <= y && isLeft(a, b, p) < 0) --wn;
if (b[1] <= y && !d3_isCCWTurn(a, b, p)) --wn;
}
a = b;
}
}
return wn !== 0;
}
function isLeft(a, b, c) {
return (b[0] - a[0]) * (c[1] - a[1]) - (c[0] - a[0]) * (b[1] - a[1]);
}
function interpolate(from, to, direction, listener) {
var a = 0, a1 = 0;
if (from == null || (a = corner(from, direction)) !== (a1 = corner(to, direction)) || comparePoints(from, to) < 0 ^ direction > 0) {
......@@ -4187,20 +4190,17 @@ d3 = function() {
if (arguments.length) return hull(vertices);
function hull(data) {
if (data.length < 3) return [];
var fx = d3_functor(x), fy = d3_functor(y), n = data.length, points = [], flipped_points = [];
for (var i = 0; i < n; i++) {
var fx = d3_functor(x), fy = d3_functor(y), i, n = data.length, points = [], flippedPoints = [];
for (i = 0; i < n; i++) {
points.push([ +fx.call(this, data[i], i), +fy.call(this, data[i], i), i ]);
}
points.sort(function(a, b) {
return a[0] - b[0] || a[1] - b[1];
});
for (var i = 0; i < n; i++) flipped_points.push([ points[i][0], -points[i][1] ]);
var uhull = d3_geom_hull_find_upper_hull(points);
var lhull = d3_geom_hull_find_upper_hull(flipped_points);
var skip_l = lhull[0] === uhull[0], skip_r = lhull[lhull.length - 1] === uhull[uhull.length - 1], poly = [];
for (var i = uhull.length - 1; i >= 0; i--) poly.push(data[points[uhull[i]][2]]);
for (var i = +skip_l; i < lhull.length - skip_r; i++) poly.push(data[points[lhull[i]][2]]);
return poly;
points.sort(d3_geom_hullOrder);
for (i = 0; i < n; i++) flippedPoints.push([ points[i][0], -points[i][1] ]);
var upper = d3_geom_hullUpper(points), lower = d3_geom_hullUpper(flippedPoints);
var skipLeft = lower[0] === upper[0], skipRight = lower[lower.length - 1] === upper[upper.length - 1], polygon = [];
for (i = upper.length - 1; i >= 0; --i) polygon.push(data[points[upper[i]][2]]);
for (i = +skipLeft; i < lower.length - skipRight; ++i) polygon.push(data[points[lower[i]][2]]);
return polygon;
}
hull.x = function(_) {
return arguments.length ? (x = _, hull) : x;
......@@ -4210,18 +4210,18 @@ d3 = function() {
};
return hull;
};
function d3_geom_hull_find_upper_hull(points) {
function d3_geom_hullUpper(points) {
var n = points.length, hull = [ 0, 1 ], hs = 2;
for (var i = 2; i < n; i++) {
while (hs > 1 && !d3_geom_hull_CW(points[hull[hs - 2]], points[hull[hs - 1]], points[i])) {
while (hs > 1 && d3_isCCWTurn(points[hull[hs - 2]], points[hull[hs - 1]], points[i])) {
hs--;
}
hull[hs++] = i;
}
return hull.slice(0, hs);
}
function d3_geom_hull_CW(a, b, c) {
return (b[0] - a[0]) * (c[1] - a[1]) - (b[1] - a[1]) * (c[0] - a[0]) > 0;
function d3_geom_hullOrder(a, b) {
return a[0] - b[0] || a[1] - b[1];
}
d3.geom.polygon = function(coordinates) {
d3_subclass(coordinates, d3_geom_polygonPrototype);
......
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......@@ -79,9 +79,9 @@ function d3_geo_clipExtent(x0, y0, x1, y1) {
for (var j = 1, v = polygon[i], m = v.length, a = v[0], b; j < m; ++j) {
b = v[j];
if (a[1] <= y) {
if (b[1] > y && isLeft(a, b, p) > 0) ++wn;
if (b[1] > y && d3_isCCWTurn(a, b, p)) ++wn;
} else {
if (b[1] <= y && isLeft(a, b, p) < 0) --wn;
if (b[1] <= y && !d3_isCCWTurn(a, b, p)) --wn;
}
a = b;
}
......@@ -89,10 +89,6 @@ function d3_geo_clipExtent(x0, y0, x1, y1) {
return wn !== 0;
}
function isLeft(a, b, c) {
return (b[0] - a[0]) * (c[1] - a[1]) - (c[0] - a[0]) * (b[1] - a[1]);
}
function interpolate(from, to, direction, listener) {
var a = 0, a1 = 0;
if (from == null ||
......
import "../core/functor";
import "../math/trigonometry";
import "geom";
import "point";
......@@ -10,8 +11,8 @@ import "point";
* The runtime of this algorithm is O(n log n), where n is the number of input
* points. However in practice it outperforms other O(n log n) hulls.
*
* @param vertices [[x1, y1], [x2, y2], ]
* @returns polygon [[x1, y1], [x2, y2], ]
* @param vertices [[x1, y1], [x2, y2], ...]
* @returns polygon [[x1, y1], [x2, y2], ...]
*/
d3.geom.hull = function(vertices) {
var x = d3_geom_pointX,
......@@ -45,7 +46,7 @@ d3.geom.hull = function(vertices) {
// construct the polygon, removing possible duplicate endpoints
var skipLeft = lower[0] === upper[0],
skipRight = lower[lower.length - 1] === upper[upper.length - 1]),
skipRight = lower[lower.length - 1] === upper[upper.length - 1],
polygon = [];
for (i = upper.length - 1; i >= 0; --i)
......@@ -76,7 +77,7 @@ function d3_geom_hullUpper(points) {
hs = 2; // hull size
for (var i = 2; i < n; i++) {
while (hs > 1 && !d3_geom_hull_CW(points[hull[hs-2]], points[hull[hs-1]], points[i])) {
while (hs > 1 && !d3_isCCWTurn(points[hull[hs-2]], points[hull[hs-1]], points[i])) {
hs --;
}
hull[hs++] = i;
......@@ -85,11 +86,5 @@ function d3_geom_hullUpper(points) {
return hull.slice(0, hs);
}
// are three points a, b, c in clockwise order?
// i.e. is the sign of (b-a)x(c-a) positive?
function d3_geom_hull_CW(a, b, c) {
return (b[0] - a[0]) * (c[1] - a[1]) - (b[1] - a[1]) * (c[0] - a[0]) > 0;
}
// comparator for ascending sort by x-coord first, y-coord second
function d3_geom_hullOrder(a, b) { return a[0] - b[0] || a[1] - b[1]; }
......@@ -10,6 +10,22 @@ function d3_sgn(x) {
return x > 0 ? 1 : x < 0 ? -1 : 0;
}
// returns true iff the [x,y] points a, b, c form a counter-clockwise turn in
// the traditional Cartesian coordinate system (i.e. x value grows from left
// to right, y value grows from bottom to top)
function d3_isCCWTurn(a, b, c) {
return d3_cross2d(a, b, c) > 0;
}
// 2D cross product of OA and OB vectors, i.e. z-component of their 3D cross
// product, in traditional Cartesian coordinate system (x value grows from
// left to right, y value grows from bottom to top). Returns a positive value
// if OAB makes a counter-clockwise turn, negative for clockwise turn, and
// zero if the points are collinear.
function d3_cross2d(o, a, b) {
return (a[0] - o[0]) * (b[1] - o[1]) - (a[1] - o[1]) * (b[0] - o[0]);
}
function d3_acos(x) {
return x > 1 ? 0 : x < -1 ? π : Math.acos(x);
}
......
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