new function() { var EPSILON = 10e-12; var TOLERANCE = 10e-6; var MAX_RECURSE = 20; var MAX_ITERATE = 20; /** * This method is analogous to paperjs#PathItem.getIntersections */ paper.PathItem.prototype.getIntersections2 = function(path) { // First check the bounds of the two paths. If they don't intersect, // we don't need to iterate through their curves. if (!this.getBounds().touches(path.getBounds())) return []; var locations = [], curves1 = this.getCurves(), curves2 = path.getCurves(), length2 = curves2.length, values2 = [], i; for (var i = 0; i < length2; i++) values2[i] = curves2[i].getValues(); for (var i = 0, l = curves1.length; i < l; i++) { var curve1 = curves1[i], values1 = curve1.getValues(); var linear1 = Curve.isLinear(values1); for (var j = 0; j < length2; j++) { var value2 = values2[j]; var linear2 = Curve.isLinear(value2); var intersect = linear1 && linear2 ? getLineLineIntersection : linear1 || linear2 ? getCurveLineIntersections : getCurveIntersections; intersect(values1, value2, curve1, curves2[j], locations); } } return locations; }; /** * Passing null for parameter leads to lazy determination of parameter values in * CurveLocation#getParameter() only once they are requested. */ function addLocation(locations, curve1, parameter, point, curve2) { // Avoid duplicates when hitting segments (closed paths too) var first = locations[0], last = locations[locations.length - 1]; if ((!first || !point.equals(first._point)) && (!last || !point.equals(last._point))) locations.push(new CurveLocation(curve1, parameter, point, curve2)); } /** * This method is analogous to paperjs#Curve.getIntersections * @param {[type]} v1 * @param {[type]} v2 * @param {[type]} curve1 * @param {[type]} curve2 * @param {[type]} locations * @param {[type]} _v1t - Only used for recusion * @param {[type]} _v2t - Only used for recusion */ function getCurveIntersections(v1, v2, curve1, curve2, locations, _v1t, _v2t, _recurseDepth) { _recurseDepth = (_recurseDepth || 0) + 1; // Avoid endless recursion. // Perhaps we should fall back to a more expensive method after this, but // so far endless recursion happens only when there is no real intersection // and the infinite fatline continue to intersect with the other curve // outside its bounds! if (_recurseDepth > MAX_RECURSE) return; // cache the original parameter range. _v1t = _v1t || { t1: 0, t2: 1 }; _v2t = _v2t || { t1: 0, t2: 1 }; var v1t = { t1: _v1t.t1, t2: _v1t.t2 }; var v2t = { t1: _v2t.t1, t2: _v2t.t2 }; // Get the clipped parts from the original curve, to avoid cumulative errors var _v1 = Curve.getPart(v1, v1t.t1, v1t.t2); var _v2 = Curve.getPart(v2, v2t.t1, v2t.t2); // markCurve(_v1, '#f0f', true); // markCurve(_v2, '#0ff', false); var nuT, parts, tmpt = { t1: null, t2: null }, iterate = 0; // Loop until both parameter range converge. We have to handle the // degenerate case seperately, where fat-line clipping can become // numerically unstable when one of the curves has converged to a point and // the other hasn't. while (iterate < MAX_ITERATE && (Math.abs(v1t.t2 - v1t.t1) > TOLERANCE || Math.abs(v2t.t2 - v2t.t1) > TOLERANCE)) { ++iterate; // First we clip v2 with v1's fat-line tmpt.t1 = v2t.t1; tmpt.t2 = v2t.t2; var intersects1 = clipFatLine(_v1, _v2, tmpt), intersects2 = 0; // Stop if there are no possible intersections if (intersects1 === 0) break; if (intersects1 > 0) { // Get the clipped parts from the original v2, to avoid cumulative // errors ...and reuse some objects. v2t.t1 = tmpt.t1; v2t.t2 = tmpt.t2; _v2 = Curve.getPart(v2, v2t.t1, v2t.t2); // markCurve(_v2, '#0ff', false); // Next we clip v1 with nuv2's fat-line tmpt.t1 = v1t.t1; tmpt.t2 = v1t.t2; intersects2 = clipFatLine(_v2, _v1, tmpt); // Stop if there are no possible intersections if (intersects2 === 0) break; if (intersects1 > 0) { // Get the clipped parts from the original v2, to avoid // cumulative errors v1t.t1 = tmpt.t1; v1t.t2 = tmpt.t2; _v1 = Curve.getPart(v1, v1t.t1, v1t.t2); } // markCurve(_v1, '#f0f', true); } // Get the clipped parts from the original v1 // Check if there could be multiple intersections if (intersects1 < 0 || intersects2 < 0) { // Subdivide the curve which has converged the least from the // original range [0,1], which would be the curve with the largest // parameter range after clipping if (v1t.t2 - v1t.t1 > v2t.t2 - v2t.t1) { // subdivide _v1 and recurse nuT = (_v1t.t1 + _v1t.t2) / 2; getCurveIntersections(v1, v2, curve1, curve2, locations, { t1: _v1t.t1, t2: nuT }, _v2t, _recurseDepth); getCurveIntersections(v1, v2, curve1, curve2, locations, { t1: nuT, t2: _v1t.t2 }, _v2t, _recurseDepth); break; } else { // subdivide _v2 and recurse nuT = (_v2t.t1 + _v2t.t2) / 2; getCurveIntersections(v1, v2, curve1, curve2, locations, _v1t, { t1: _v2t.t1, t2: nuT }, _recurseDepth); getCurveIntersections(v1, v2, curve1, curve2, locations, _v1t, { t1: nuT, t2: _v2t.t2 }, _recurseDepth); break; } } // We need to bailout of clipping and try a numerically stable method if // any of the following are true. // 1. One of the parameter ranges is converged to a point. // 2. Both of the parameter ranges have converged reasonably well // (according to TOLERENCE). // 3. One of the parameter range is converged enough so that it is // *flat enough* to // calculate line curve intersection implicitly. // // Check if one of the parameter range has converged completely to a // point. Now things could get only worse if we iterate more for the // other curve to converge if it hasn't yet happened so. var v1Converged = (Math.abs(v1t.t2 - v1t.t1) < EPSILON), v2Converged = (Math.abs(v2t.t2 - v2t.t1) < EPSILON); if (v1Converged || v2Converged) { addLocation(locations, curve1, null, v1Converged ? curve1.getPointAt(v1t.t1, true) : curve2.getPointAt(v2t.t1, true), curve2); break; } if (Math.abs(v1t.t2 - v1t.t1) <= TOLERANCE && Math.abs(v2t.t2 - v2t.t1) <= TOLERANCE) { // Both parameter ranges have converged. addLocation(locations, curve1, v1t.t1, curve1.getPointAt(v1t.t1, true), curve2); break; } // see if either or both of the curves are flat enough to be treated // as lines. var curve1Flat = Curve.isFlatEnough(_v1, TOLERANCE), curve2Flat = Curve.isFlatEnough(_v2, TOLERANCE); if (curve1Flat && curve2Flat) { getLineLineIntersection(_v1, _v2, curve1, curve2, locations); break; } if (curve1Flat || curve2Flat) { // Use curve line intersection method while specifying which // curve to be treated as line getCurveLineIntersections(_v1, _v2, curve1, curve2, locations, curve1Flat); break; } } } /** * Clip curve V2 with fat-line of v1 * @param {Array} v1 section of the first curve, for which we will make a * fat-line * @param {Array} v2 section of the second curve; we will clip this curve with * the fat-line of v1 * @param {Object} v2t the parameter range of v2 * @return {Number} 0: no Intersection, 1: one intersection, -1: more than one * ntersection */ function clipFatLine(v1, v2, v2t) { // first curve, P var p0x = v1[0], p0y = v1[1], p1x = v1[2], p1y = v1[3], p2x = v1[4], p2y = v1[5], p3x = v1[6], p3y = v1[7]; // second curve, Q var q0x = v2[0], q0y = v2[1], q1x = v2[2], q1y = v2[3], q2x = v2[4], q2y = v2[5], q3x = v2[6], q3y = v2[7]; // Calculate the fat-line L for P is the baseline l and two // offsets which completely encloses the curve P. var d1 = getSignedDistance(p0x, p0y, p3x, p3y, p1x, p1y) || 0; var d2 = getSignedDistance(p0x, p0y, p3x, p3y, p2x, p2y) || 0; var factor = d1 * d2 > 0 ? 3 / 4 : 4 / 9; var dmin = factor * Math.min(0, d1, d2); var dmax = factor * Math.max(0, d1, d2); // Calculate non-parametric bezier curve D(ti, di(t)) - di(t) is the // distance of Q from the baseline l of the fat-line, ti is equally spaced // in [0, 1] var dq0 = getSignedDistance(p0x, p0y, p3x, p3y, q0x, q0y); var dq1 = getSignedDistance(p0x, p0y, p3x, p3y, q1x, q1y); var dq2 = getSignedDistance(p0x, p0y, p3x, p3y, q2x, q2y); var dq3 = getSignedDistance(p0x, p0y, p3x, p3y, q3x, q3y); // Find the minimum and maximum distances from l, this is useful for // checking whether the curves intersect with each other or not. var mindist = Math.min(dq0, dq1, dq2, dq3); var maxdist = Math.max(dq0, dq1, dq2, dq3); // If the fatlines don't overlap, we have no intersections! if (dmin > maxdist || dmax < mindist) return 0; var tmp; if (dq3 < dq0) { tmp = dmin; dmin = dmax; dmax = tmp; } var Dt = getConvexHull(dq0, dq1, dq2, dq3); // Calculate the convex hull for non-parametric bezier curve D(ti, di(t)) // Now we clip the convex hulls for D(ti, di(t)) with dmin and dmax // for the coorresponding t values (tmin, tmax): Portions of curve v2 before // tmin and after tmax can safely be clipped away var tmaxdmin = -Infinity, ixd, ixdx, i, len, inv_m; var tmin = Infinity, tmax = -Infinity, Dtl, dtlx1, dtly1, dtlx2, dtly2; for (i = 0, len = Dt.length; i < len; i++) { Dtl = Dt[i]; dtlx1 = Dtl[0]; dtly1 = Dtl[1]; dtlx2 = Dtl[2]; dtly2 = Dtl[3]; if (dtly2 < dtly1) { tmp = dtly2; dtly2 = dtly1; dtly1 = tmp; tmp = dtlx2; dtlx2 = dtlx1; dtlx1 = tmp; } // we know that (dtlx2 - dtlx1) is never 0 inv_m = (dtly2 - dtly1) / (dtlx2 - dtlx1); if (dmin >= dtly1 && dmin <= dtly2) { ixdx = dtlx1 + (dmin - dtly1) / inv_m; if (ixdx < tmin) tmin = ixdx; if (ixdx > tmaxdmin) tmaxdmin = ixdx; } if (dmax >= dtly1 && dmax <= dtly2) { ixdx = dtlx1 + (dmax - dtly1) / inv_m; if (ixdx > tmax) tmax = ixdx; if (ixdx < tmin) tmin = 0; } } // Return the parameter values for v2 for which we can be sure that the // intersection with v1 lies within. if (tmin !== Infinity && tmax !== -Infinity) { var mindmin = Math.min(dmin, dmax); var mindmax = Math.max(dmin, dmax); if (dq3 > mindmin && dq3 < mindmax) tmax = 1; if (dq0 > mindmin && dq0 < mindmax) tmin = 0; if (tmaxdmin > tmax) tmax = 1; // tmin and tmax are within the range (0, 1). We need to project it to // the original parameter range for v2. var v2tmin = v2t.t1; var tdiff = (v2t.t2 - v2tmin); v2t.t1 = v2tmin + tmin * tdiff; v2t.t2 = v2tmin + tmax * tdiff; // If the new parameter range fails to converge by atleast 20% of the // original range, possibly we have multiple intersections. We need to // subdivide one of the curves. if ((tdiff - (v2t.t2 - v2t.t1))/tdiff >= 0.2) return 1; } // TODO: Try checking with a perpendicular fatline to see if the curves // overlap if it is any faster than this if (Curve.getBounds(v1).touches(Curve.getBounds(v2))) return -1; return 0; } /** * Calculate the convex hull for the non-paramertic bezier curve D(ti, di(t)). * The ti is equally spaced across [0..1] — [0, 1/3, 2/3, 1] for * di(t), [dq0, dq1, dq2, dq3] respectively. In other words our CVs for the * curve are already sorted in the X axis in the increasing order. Calculating * convex-hull is much easier than a set of arbitrary points. */ function getConvexHull(dq0, dq1, dq2, dq3) { var distq1 = getSignedDistance(0, dq0, 1, dq3, 1 / 3, dq1); var distq2 = getSignedDistance(0, dq0, 1, dq3, 2 / 3, dq2); var hull; // Check if [1/3, dq1] and [2/3, dq2] are on the same side of line // [0,dq0, 1,dq3] if (distq1 * distq2 < 0) { // dq1 and dq2 lie on different sides on [0, q0, 1, q3] // Convexhull is a quadrilateral and line [0, q0, 1, q3] is NOT part of // the convexhull so we are pretty much done here. hull = [ [ 0, dq0, 1 / 3, dq1 ], [ 1 / 3, dq1, 1, dq3 ], [ 2 / 3, dq2, 0, dq0 ], [ 1, dq3, 2 / 3, dq2 ] ]; } else { // dq1 and dq2 lie on the same sides on [0, q0, 1, q3]. c-hull can be a // triangle or a quadrilateral and line [0, q0, 1, q3] is part of the // c-hull. Check if the hull is a triangle or a quadrilateral var dqmin, dqmax, dqapex1, dqapex2; distq1 = Math.abs(distq1); distq2 = Math.abs(distq2); var vqa1a2x, vqa1a2y, vqa1Maxx, vqa1Maxy, vqa1Minx, vqa1Miny; if (distq1 > distq2) { dqmin = [ 2 / 3, dq2 ]; dqmax = [ 1 / 3, dq1 ]; // apex is dq3 and the other apex point is dq0 vector // dqapex->dqapex2 or base vector which is already part of c-hull vqa1a2x = 1; vqa1a2y = dq3 - dq0; // vector dqapex->dqmax vqa1Maxx = 2 / 3; vqa1Maxy = dq3 - dq1; // vector dqapex->dqmin vqa1Minx = 1 / 3; vqa1Miny = dq3 - dq2; } else { dqmin = [ 1 / 3, dq1 ]; dqmax = [ 2 / 3, dq2 ]; // apex is dq0 in this case, and the other apex point is dq3 vector // dqapex->dqapex2 or base vector which is already part of c-hull vqa1a2x = -1; vqa1a2y = dq0 - dq3; // vector dqapex->dqmax vqa1Maxx = -2 / 3; vqa1Maxy = dq0 - dq2; // vector dqapex->dqmin vqa1Minx = -1 / 3; vqa1Miny = dq0 - dq1; } // Compare cross products of these vectors to determine, if // point is in triangles [ dq3, dqMax, dq0 ] or [ dq0, dqMax, dq3 ] var vcrossa1a2_a1Min = vqa1a2x * vqa1Miny - vqa1a2y * vqa1Minx; var vcrossa1Max_a1Min = vqa1Maxx * vqa1Miny - vqa1Maxy * vqa1Minx; if (vcrossa1Max_a1Min * vcrossa1a2_a1Min < 0) { // Point [2/3, dq2] is inside the triangle and c-hull is a triangle hull = [ [ 0, dq0, dqmax[0], dqmax[1] ], [ dqmax[0], dqmax[1], 1, dq3 ], [ 1, dq3, 0, dq0 ] ]; } else { // Convexhull is a quadrilateral and we need all lines in the // correct order where line [0, q0, 1, q3] is part of the c-hull hull = [ [ 0, dq0, 1 / 3, dq1 ], [ 1 / 3, dq1, 2 / 3, dq2 ], [ 2 / 3, dq2, 1, dq3 ], [ 1, dq3, 0, dq0 ] ]; } } return hull; } // This is basically an "unrolled" version of #Line.getDistance() with sign // May be a static method could be better! function getSignedDistance(a1x, a1y, a2x, a2y, bx, by) { var m = (a2y - a1y) / (a2x - a1x), b = a1y - (m * a1x); return (by - (m * bx) - b) / Math.sqrt(m * m + 1); } /** * Intersections between curve and line becomes rather simple here mostly * because of Numerical class. We can rotate the curve and line so that the line * is on X axis, and solve the implicit equations for X axis and the curve */ function getCurveLineIntersections(v1, v2, curve1, curve2, locations, _flip) { if (_flip === undefined) _flip = Curve.isLinear(v1); var vc = _flip ? v2 : v1, vl = _flip ? v1 : v2, l1x = vl[0], l1y = vl[1], l2x = vl[6], l2y = vl[7], // Rotate both the curve and line around l1 so that line is on x axis lvx = l2x - l1x, lvy = l2y - l1y, // Angle with x axis (1, 0) angle = Math.atan2(-lvy, lvx), sin = Math.sin(angle), cos = Math.cos(angle), // (rl1x, rl1y) = (0, 0) rl2x = lvx * cos - lvy * sin, rl2y = lvy * cos + lvx * sin, vcr = []; for(var i = 0; i < 8; i += 2) { var x = vc[i] - l1x, y = vc[i + 1] - l1y; vcr.push( x * cos - y * sin, y * cos + x * sin); } var roots = [], count = Curve.solveCubic(vcr, 1, 0, roots); // NOTE: count could theoretically be -1 for inifnite solutions, although // that should only happen with lines, in which case we should not be here. for (var i = 0; i < count; i++) { var t = roots[i]; if (t >= 0 && t <= 1) { var point = Curve.evaluate(vcr, t, true, 0); // We do have a point on the infinite line. Check if it falls on the // line *segment*. if (point.x >= 0 && point.x <= rl2x) addLocation(locations, _flip ? curve2 : curve1, // The actual intersection point t, Curve.evaluate(vc, t, true, 0), _flip ? curve1 : curve2); } } } function getLineLineIntersection(v1, v2, curve1, curve2, locations) { var point = Line.intersect( v1[0], v1[1], v1[6], v1[7], v2[0], v2[1], v2[6], v2[7], false); // Passing null for parameter leads to lazy determination of parameter // values in CurveLocation#getParameter() only once they are requested. if (point) addLocation(locations, curve1, null, point, curve2); } };