src/geometry/PolygonCut.h

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• Last update: 2025-07-19 20:33:24+09:00

Depends on

• src/geometry/Point.h

Code

/**
 * Author: Ulf Lundstrom
 * Date: 2009-03-21
 * License: CC0
 * Source:
 * Description:\\
\begin{minipage}{75mm}
 Returns a vector with the vertices of a polygon with everything to the left of the line going from s to e cut away.
\end{minipage}
\begin{minipage}{15mm}
\vspace{-6mm}
\includegraphics[width=\textwidth]{src/geometry/PolygonCut}
\vspace{-6mm}
\end{minipage}
 * Usage:
 * 	vector<P> p = ...;
 * 	p = polygonCut(p, P(0,0), P(1,0));
 * Status: tested but not extensively
 */
#pragma once

#include "src/geometry/Point.h"

typedef Point<double> P;
vector<P> polygonCut(const vector<P>& poly, P s, P e) {
	vector<P> res;
	rep(i,0,sz(poly)) {
		P cur = poly[i], prev = i ? poly[i-1] : poly.back();
		auto a = s.cross(e, cur), b = s.cross(e, prev);
		if ((a < 0) != (b < 0))
			res.push_back(cur + (prev - cur) * (a / (a - b)));
		if (a < 0)
			res.push_back(cur);
	}
	return res;
}

Traceback (most recent call last):
  File "/opt/hostedtoolcache/Python/3.14.0/x64/lib/python3.14/site-packages/onlinejudge_verify/documentation/build.py", line 71, in _render_source_code_stat
    bundled_code = language.bundle(stat.path, basedir=basedir, options={'include_paths': [basedir]}).decode()
                   ~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/hostedtoolcache/Python/3.14.0/x64/lib/python3.14/site-packages/onlinejudge_verify/languages/cplusplus.py", line 187, in bundle
    bundler.update(path)
    ~~~~~~~~~~~~~~^^^^^^
  File "/opt/hostedtoolcache/Python/3.14.0/x64/lib/python3.14/site-packages/onlinejudge_verify/languages/cplusplus_bundle.py", line 312, in update
    raise BundleErrorAt(path, i + 1, "#pragma once found in a non-first line")
onlinejudge_verify.languages.cplusplus_bundle.BundleErrorAt: src/geometry/PolygonCut.h: line 20: #pragma once found in a non-first line

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