/* * Poly2Tri Copyright (c) 2009-2010, Poly2Tri Contributors * http://code.google.com/p/poly2tri/ * * 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 #include 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
* Positive if CCW
* Negative if CW
* 0 if collinear
*
 * A[P1,P2,P3]  =  (x1*y2 - y1*x2) + (x2*y3 - y2*x3) + (x3*y1 - y3*x1)
 *              =  (x1-x3)*(y2-y3) - (y1-y3)*(x2-x3)
 * 
*/ 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