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29 lines
874 B
TypeScript
29 lines
874 B
TypeScript
import type { GlobalPoint, LocalPoint, Triangle } from "./types";
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// Types
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/**
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* Tests if a point lies inside a triangle. This function
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* will return FALSE if the point lies exactly on the sides
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* of the triangle.
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*
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* @param triangle The triangle to test the point for
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* @param p The point to test whether is in the triangle
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* @returns TRUE if the point is inside of the triangle
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*/
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export function triangleIncludesPoint<P extends GlobalPoint | LocalPoint>(
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[a, b, c]: Triangle<P>,
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p: P,
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): boolean {
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const triangleSign = (p1: P, p2: P, p3: P) =>
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(p1[0] - p3[0]) * (p2[1] - p3[1]) - (p2[0] - p3[0]) * (p1[1] - p3[1]);
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const d1 = triangleSign(p, a, b);
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const d2 = triangleSign(p, b, c);
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const d3 = triangleSign(p, c, a);
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const has_neg = d1 < 0 || d2 < 0 || d3 < 0;
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const has_pos = d1 > 0 || d2 > 0 || d3 > 0;
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return !(has_neg && has_pos);
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}
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