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Expose Curve. getCurveLineIntersections() for curve offsetting.

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Jürg Lehni 2017-02-05 21:59:56 +01:00
parent 8c3c771891
commit fafbd9ad36
1 changed files with 24 additions and 19 deletions
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43
src/path/Curve.js
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@ -1960,36 +1960,38 @@ new function() { // Scope for intersection using bezier fat-line clipping
* line is on the X axis, and solve the implicit equations for the X axis * line is on the X axis, and solve the implicit equations for the X axis
* and the curve. * and the curve.
*/ */
function addCurveLineIntersections(v1, v2, c1, c2, locations, param) { function getCurveLineIntersections(v, px, py, vx, vy) {
var flip = Curve.isStraight(v1), // Calculate angle to the x-axis (1, 0).
vc = flip ? v2 : v1, var angle = Math.atan2(-vy, vx),
vl = flip ? v1 : v2,
lx1 = vl[0], ly1 = vl[1],
lx2 = vl[6], ly2 = vl[7],
// Rotate both curve and line around l1 so that line is on x axis.
ldx = lx2 - lx1,
ldy = ly2 - ly1,
// Calculate angle to the x-axis (1, 0).
angle = Math.atan2(-ldy, ldx),
sin = Math.sin(angle), sin = Math.sin(angle),
cos = Math.cos(angle), cos = Math.cos(angle),
// (rlx1, rly1) = (0, 0) // (rlx1, rly1) = (0, 0)
// Calculate the curve values of the rotated curve. // Calculate the curve values of the rotated curve.
rvc = []; rv = [],
roots = [];
for(var i = 0; i < 8; i += 2) { for(var i = 0; i < 8; i += 2) {
var x = vc[i] - lx1, var x = v[i] - px,
y = vc[i + 1] - ly1; y = v[i + 1] - py;
rvc.push( rv.push(
x * cos - y * sin, x * cos - y * sin,
x * sin + y * cos); x * sin + y * cos);
} }
// Solve it for y = 0. We need to include t = 0, 1 and let addLocation() // Solve it for y = 0. We need to include t = 0, 1 and let addLocation()
// do the filtering, to catch important edge cases. // do the filtering, to catch important edge cases.
var roots = [], Curve.solveCubic(rv, 1, 0, roots, 0, 1);
count = Curve.solveCubic(rvc, 1, 0, roots, 0, 1); return roots;
}
function addCurveLineIntersections(v1, v2, c1, c2, locations, param) {
var flip = Curve.isStraight(v1),
vc = flip ? v2 : v1,
vl = flip ? v1 : v2,
x1 = vl[0], y1 = vl[1],
x2 = vl[6], y2 = vl[7],
roots = getCurveLineIntersections(vc, x1, y1, x2 - x1, y2 - y1);
// NOTE: count could be -1 for infinite solutions, but that should only // NOTE: count could be -1 for infinite solutions, but that should only
// happen with lines, in which case we should not be here. // happen with lines, in which case we should not be here.
for (var i = 0; i < count; i++) { for (var i = 0, l = roots.length; i < l; i++) {
// For each found solution on the rotated curve, get the point on // For each found solution on the rotated curve, get the point on
// the real curve and with that the location on the line. // the real curve and with that the location on the line.
var tc = roots[i], var tc = roots[i],
@ -2201,6 +2203,9 @@ new function() { // Scope for intersection using bezier fat-line clipping
pairs = null; pairs = null;
} }
return pairs; return pairs;
} },
// Exposed for use in boolean offsetting
getCurveLineIntersections: getCurveLineIntersections
}}; }};
}); });