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36 lines
1.3 KiB
JavaScript
36 lines
1.3 KiB
JavaScript
4 years ago
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function clone(p) {
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return [...p];
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}
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export function curveToBezier(pointsIn, curveTightness = 0) {
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const len = pointsIn.length;
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if (len < 3) {
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throw new Error('A curve must have at least three points.');
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}
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const out = [];
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if (len === 3) {
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out.push(clone(pointsIn[0]), clone(pointsIn[1]), clone(pointsIn[2]), clone(pointsIn[2]));
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}
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else {
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const points = [];
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points.push(pointsIn[0], pointsIn[0]);
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for (let i = 1; i < pointsIn.length; i++) {
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points.push(pointsIn[i]);
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if (i === (pointsIn.length - 1)) {
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points.push(pointsIn[i]);
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}
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}
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const b = [];
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const s = 1 - curveTightness;
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out.push(clone(points[0]));
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for (let i = 1; (i + 2) < points.length; i++) {
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const cachedVertArray = points[i];
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b[0] = [cachedVertArray[0], cachedVertArray[1]];
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b[1] = [cachedVertArray[0] + (s * points[i + 1][0] - s * points[i - 1][0]) / 6, cachedVertArray[1] + (s * points[i + 1][1] - s * points[i - 1][1]) / 6];
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b[2] = [points[i + 1][0] + (s * points[i][0] - s * points[i + 2][0]) / 6, points[i + 1][1] + (s * points[i][1] - s * points[i + 2][1]) / 6];
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b[3] = [points[i + 1][0], points[i + 1][1]];
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out.push(b[1], b[2], b[3]);
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}
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}
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return out;
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}
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