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++ /*
++ * Poly2Tri Copyright (c) 2009-2010, Poly2Tri Contributors
++ *
++ * All rights reserved.
++ *
++ * Redistribution and use in source and binary forms, with or without modification,
++ * are permitted provided that the following conditions are met:
++ *
++ * * Redistributions of source code must retain the above copyright notice,
++ * this list of conditions and the following disclaimer.
++ * * Redistributions in binary form must reproduce the above copyright notice,
++ * this list of conditions and the following disclaimer in the documentation
++ * and/or other materials provided with the distribution.
++ * * Neither the name of Poly2Tri nor the names of its contributors may be
++ * used to endorse or promote products derived from this software without specific
++ * prior written permission.
++ *
++ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
++ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
++ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
++ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
++ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
++ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
++ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
++ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
++ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
++ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
++ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
++ */
++
++ #ifndef UTILS_H
++ #define UTILS_H
++
++ // Otherwise #defines like M_PI are undeclared under Visual Studio
++ #define _USE_MATH_DEFINES
++
++ #include <exception>
++ #include <math.h>
++
++ #ifndef M_PI
++ #define M_PI (3.14159265358979323846)
++ #endif
++
++ namespace p2t {
++
++ const double PI_3div4 = 3 * M_PI / 4;
++ const double PI_div2 = 1.57079632679489661923;
++ const double EPSILON = 1e-12;
++
++ enum Orientation { CW, CCW, COLLINEAR };
++
++ /**
++ * Forumla to calculate signed area<br>
++ * Positive if CCW<br>
++ * Negative if CW<br>
++ * 0 if collinear<br>
++ * <pre>
++ * A[P1,P2,P3] = (x1*y2 - y1*x2) + (x2*y3 - y2*x3) + (x3*y1 - y3*x1)
++ * = (x1-x3)*(y2-y3) - (y1-y3)*(x2-x3)
++ * </pre>
++ */
++ Orientation Orient2d(Point& pa, Point& pb, Point& pc)
++ {
++ double detleft = (pa.x - pc.x) * (pb.y - pc.y);
++ double detright = (pa.y - pc.y) * (pb.x - pc.x);
++ double val = detleft - detright;
++ if (val > -EPSILON && val < EPSILON) {
++ return COLLINEAR;
++ } else if (val > 0) {
++ return CCW;
++ }
++ return CW;
++ }
++
++ /*
++ bool InScanArea(Point& pa, Point& pb, Point& pc, Point& pd)
++ {
++ double pdx = pd.x;
++ double pdy = pd.y;
++ double adx = pa.x - pdx;
++ double ady = pa.y - pdy;
++ double bdx = pb.x - pdx;
++ double bdy = pb.y - pdy;
++
++ double adxbdy = adx * bdy;
++ double bdxady = bdx * ady;
++ double oabd = adxbdy - bdxady;
++
++ if (oabd <= EPSILON) {
++ return false;
++ }
++
++ double cdx = pc.x - pdx;
++ double cdy = pc.y - pdy;
++
++ double cdxady = cdx * ady;
++ double adxcdy = adx * cdy;
++ double ocad = cdxady - adxcdy;
++
++ if (ocad <= EPSILON) {
++ return false;
++ }
++
++ return true;
++ }
++
++ */
++
++ bool InScanArea(Point& pa, Point& pb, Point& pc, Point& pd)
++ {
++ double oadb = (pa.x - pb.x)*(pd.y - pb.y) - (pd.x - pb.x)*(pa.y - pb.y);
++ if (oadb >= -EPSILON) {
++ return false;
++ }
++
++ double oadc = (pa.x - pc.x)*(pd.y - pc.y) - (pd.x - pc.x)*(pa.y - pc.y);
++ if (oadc <= EPSILON) {
++ return false;
++ }
++ return true;
++ }
++
++ }
++
++ #endif
++