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94 lines
2.4 KiB
94 lines
2.4 KiB
// Javascript program to check if two given line segments intersect
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// Given three collinear points p, q, r, the function checks if
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// point q lies on line segment 'pr'
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function onSegment(p, q, r)
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{
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if (q.x <= Math.max(p.x, r.x) && q.x >= Math.min(p.x, r.x) &&
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q.y <= Math.max(p.y, r.y) && q.y >= Math.min(p.y, r.y))
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return true;
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return false;
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}
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// To find orientation of ordered triplet (p, q, r).
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// The function returns following values
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// 0 --> p, q and r are collinear
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// 1 --> Clockwise
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// 2 --> Counterclockwise
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function orientation(p, q, r)
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{
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// See https://www.geeksforgeeks.org/orientation-3-ordered-points/
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// for details of below formula.
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let val = (q.y - p.y) * (r.x - q.x) -
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(q.x - p.x) * (r.y - q.y);
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if (val == 0) return 0; // collinear
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return (val > 0)? 1: 2; // clock or counterclock wise
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}
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// The main function that returns true if line segment 'p1q1'
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// and 'p2q2' intersect.
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function doIntersect(p1, q1, p2, q2)
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{
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// Find the four orientations needed for general and
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// special cases
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let o1 = orientation(p1, q1, p2);
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let o2 = orientation(p1, q1, q2);
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let o3 = orientation(p2, q2, p1);
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let o4 = orientation(p2, q2, q1);
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// General case
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if (o1 != o2 && o3 != o4)
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return true;
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// Special Cases
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// p1, q1 and p2 are collinear and p2 lies on segment p1q1
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if (o1 == 0 && onSegment(p1, p2, q1)) return true;
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// p1, q1 and q2 are collinear and q2 lies on segment p1q1
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if (o2 == 0 && onSegment(p1, q2, q1)) return true;
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// p2, q2 and p1 are collinear and p1 lies on segment p2q2
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if (o3 == 0 && onSegment(p2, p1, q2)) return true;
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// p2, q2 and q1 are collinear and q1 lies on segment p2q2
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if (o4 == 0 && onSegment(p2, q1, q2)) return true;
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return false; // Doesn't fall in any of the above cases
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}
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function test_intersect(){
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// Driver code
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let p1 = new Vector(1, 1);
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let q1 = new Vector(10, 1);
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let p2 = new Vector(1, 2);
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let q2 = new Vector(10, 2);
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if(doIntersect(p1, q1, p2, q2))
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console.log("Yes<br>");
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else
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console.log("No<br>");
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p1 = new Vector(10, 1); q1 = new Vector(0, 10);
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p2 = new Vector(0, 0); q2 = new Vector(10, 10);
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if(doIntersect(p1, q1, p2, q2))
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console.log("Yes<br>");
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else
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console.log("No<br>");
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p1 = new Vector(-5, -5); q1 = new Vector(0, 0);
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p2 = new Vector(1, 1); q2 = new Vector(10, 10);;
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if(doIntersect(p1, q1, p2, q2))
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console.log("Yes<br>");
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else
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console.log("No<br>");
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}
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// This code is contributed by avanitrachhadiya2155
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