mirror of https://github.com/axmolengine/axmol.git
131 lines
3.7 KiB
C++
131 lines
3.7 KiB
C++
/*
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* Poly2Tri Copyright (c) 2009-2018, Poly2Tri Contributors
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* https://github.com/jhasse/poly2tri
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*
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without modification,
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* are permitted provided that the following conditions are met:
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*
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* * Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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* * Neither the name of Poly2Tri nor the names of its contributors may be
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* used to endorse or promote products derived from this software without specific
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* prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#pragma once
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// Otherwise #defines like M_PI are undeclared under Visual Studio
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#define _USE_MATH_DEFINES
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#include "shapes.h"
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#include <cmath>
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#include <exception>
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// C99 removes M_PI from math.h
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#ifndef M_PI
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#define M_PI 3.14159265358979323846264338327
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#endif
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namespace p2t {
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const double PI_3div4 = 3 * M_PI / 4;
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const double PI_div2 = 1.57079632679489661923;
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const double EPSILON = 1e-12;
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enum Orientation { CW, CCW, COLLINEAR };
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/**
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* Forumla to calculate signed area<br>
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* Positive if CCW<br>
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* Negative if CW<br>
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* 0 if collinear<br>
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* <pre>
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* A[P1,P2,P3] = (x1*y2 - y1*x2) + (x2*y3 - y2*x3) + (x3*y1 - y3*x1)
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* = (x1-x3)*(y2-y3) - (y1-y3)*(x2-x3)
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* </pre>
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*/
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Orientation Orient2d(const Point& pa, const Point& pb, const Point& pc)
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{
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double detleft = (pa.x - pc.x) * (pb.y - pc.y);
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double detright = (pa.y - pc.y) * (pb.x - pc.x);
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double val = detleft - detright;
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// Using a tolerance here fails on concave-by-subepsilon boundaries
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// if (val > -EPSILON && val < EPSILON) {
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// Using == on double makes -Wfloat-equal warnings yell at us
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if (std::fpclassify(val) == FP_ZERO) {
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return COLLINEAR;
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} else if (val > 0) {
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return CCW;
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}
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return CW;
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}
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/*
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bool InScanArea(Point& pa, Point& pb, Point& pc, Point& pd)
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{
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double pdx = pd.x;
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double pdy = pd.y;
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double adx = pa.x - pdx;
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double ady = pa.y - pdy;
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double bdx = pb.x - pdx;
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double bdy = pb.y - pdy;
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double adxbdy = adx * bdy;
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double bdxady = bdx * ady;
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double oabd = adxbdy - bdxady;
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if (oabd <= EPSILON) {
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return false;
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}
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double cdx = pc.x - pdx;
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double cdy = pc.y - pdy;
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double cdxady = cdx * ady;
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double adxcdy = adx * cdy;
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double ocad = cdxady - adxcdy;
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if (ocad <= EPSILON) {
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return false;
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}
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return true;
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}
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*/
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bool InScanArea(const Point& pa, const Point& pb, const Point& pc, const Point& pd)
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{
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double oadb = (pa.x - pb.x)*(pd.y - pb.y) - (pd.x - pb.x)*(pa.y - pb.y);
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if (oadb >= -EPSILON) {
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return false;
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}
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double oadc = (pa.x - pc.x)*(pd.y - pc.y) - (pd.x - pc.x)*(pa.y - pc.y);
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if (oadc <= EPSILON) {
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return false;
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}
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return true;
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}
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}
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