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303 lines
8.7 KiB
C++
303 lines
8.7 KiB
C++
/*M///////////////////////////////////////////////////////////////////////////////////////
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//
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// IMPORTANT: READ BEFORE DOWNLOADING, COPYING, INSTALLING OR USING.
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//
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// By downloading, copying, installing or using the software you agree to this license.
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// If you do not agree to this license, do not download, install,
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// copy or use the software.
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//
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//
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// License Agreement
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// For Open Source Computer Vision Library
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//
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// Copyright (C) 2000-2008, Intel Corporation, all rights reserved.
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// Copyright (C) 2008-2011, Willow Garage Inc., all rights reserved.
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// Third party copyrights are property of their respective owners.
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//
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// @Authors
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// Nghia Ho, nghiaho12@yahoo.com
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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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// * Redistribution's 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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//
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// * Redistribution's 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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//
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// * The name of OpenCV Foundation may not be used to endorse or promote products
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// derived from this software without specific prior written permission.
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//
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// This software is provided by the copyright holders and contributors "as is" and
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// any express or implied warranties, including, but not limited to, the implied
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// warranties of merchantability and fitness for a particular purpose are disclaimed.
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// In no event shall the OpenCV Foundation or contributors be liable for any direct,
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// indirect, incidental, special, exemplary, or consequential damages
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// (including, but not limited to, procurement of substitute goods or services;
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// loss of use, data, or profits; or business interruption) however caused
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// and on any theory of liability, whether in contract, strict liability,
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// or tort (including negligence or otherwise) arising in any way out of
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// the use of this software, even if advised of the possibility of such damage.
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//
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//M*/
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#include "precomp.hpp"
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namespace cv
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{
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int rotatedRectangleIntersection( const RotatedRect& rect1, const RotatedRect& rect2, OutputArray intersectingRegion )
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{
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CV_INSTRUMENT_REGION();
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// L2 metric
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const float samePointEps = std::max(1e-16f, 1e-6f * (float)std::max(rect1.size.area(), rect2.size.area()));
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Point2f vec1[4], vec2[4];
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Point2f pts1[4], pts2[4];
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std::vector <Point2f> intersection; intersection.reserve(24);
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rect1.points(pts1);
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rect2.points(pts2);
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int ret = INTERSECT_FULL;
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// Specical case of rect1 == rect2
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{
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bool same = true;
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for( int i = 0; i < 4; i++ )
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{
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if( fabs(pts1[i].x - pts2[i].x) > samePointEps || (fabs(pts1[i].y - pts2[i].y) > samePointEps) )
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{
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same = false;
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break;
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}
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}
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if(same)
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{
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intersection.resize(4);
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for( int i = 0; i < 4; i++ )
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{
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intersection[i] = pts1[i];
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}
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Mat(intersection).copyTo(intersectingRegion);
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return INTERSECT_FULL;
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}
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}
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// Line vector
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// A line from p1 to p2 is: p1 + (p2-p1)*t, t=[0,1]
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for( int i = 0; i < 4; i++ )
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{
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vec1[i].x = pts1[(i+1)%4].x - pts1[i].x;
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vec1[i].y = pts1[(i+1)%4].y - pts1[i].y;
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vec2[i].x = pts2[(i+1)%4].x - pts2[i].x;
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vec2[i].y = pts2[(i+1)%4].y - pts2[i].y;
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}
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// Line test - test all line combos for intersection
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for( int i = 0; i < 4; i++ )
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{
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for( int j = 0; j < 4; j++ )
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{
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// Solve for 2x2 Ax=b
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float x21 = pts2[j].x - pts1[i].x;
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float y21 = pts2[j].y - pts1[i].y;
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float vx1 = vec1[i].x;
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float vy1 = vec1[i].y;
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float vx2 = vec2[j].x;
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float vy2 = vec2[j].y;
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float det = vx2*vy1 - vx1*vy2;
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float t1 = (vx2*y21 - vy2*x21) / det;
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float t2 = (vx1*y21 - vy1*x21) / det;
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// This takes care of parallel lines
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if( cvIsInf(t1) || cvIsInf(t2) || cvIsNaN(t1) || cvIsNaN(t2) )
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{
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continue;
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}
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if( t1 >= 0.0f && t1 <= 1.0f && t2 >= 0.0f && t2 <= 1.0f )
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{
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float xi = pts1[i].x + vec1[i].x*t1;
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float yi = pts1[i].y + vec1[i].y*t1;
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intersection.push_back(Point2f(xi,yi));
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}
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}
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}
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if( !intersection.empty() )
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{
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ret = INTERSECT_PARTIAL;
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}
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// Check for vertices from rect1 inside recct2
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for( int i = 0; i < 4; i++ )
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{
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// We do a sign test to see which side the point lies.
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// If the point all lie on the same sign for all 4 sides of the rect,
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// then there's an intersection
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int posSign = 0;
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int negSign = 0;
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float x = pts1[i].x;
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float y = pts1[i].y;
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for( int j = 0; j < 4; j++ )
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{
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// line equation: Ax + By + C = 0
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// see which side of the line this point is at
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float A = -vec2[j].y;
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float B = vec2[j].x;
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float C = -(A*pts2[j].x + B*pts2[j].y);
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float s = A*x+ B*y+ C;
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if( s >= 0 )
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{
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posSign++;
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}
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else
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{
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negSign++;
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}
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}
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if( posSign == 4 || negSign == 4 )
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{
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intersection.push_back(pts1[i]);
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}
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}
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// Reverse the check - check for vertices from rect2 inside recct1
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for( int i = 0; i < 4; i++ )
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{
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// We do a sign test to see which side the point lies.
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// If the point all lie on the same sign for all 4 sides of the rect,
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// then there's an intersection
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int posSign = 0;
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int negSign = 0;
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float x = pts2[i].x;
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float y = pts2[i].y;
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for( int j = 0; j < 4; j++ )
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{
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// line equation: Ax + By + C = 0
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// see which side of the line this point is at
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float A = -vec1[j].y;
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float B = vec1[j].x;
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float C = -(A*pts1[j].x + B*pts1[j].y);
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float s = A*x + B*y + C;
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if( s >= 0 )
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{
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posSign++;
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}
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else
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{
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negSign++;
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}
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}
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if( posSign == 4 || negSign == 4 )
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{
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intersection.push_back(pts2[i]);
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}
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}
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int N = (int)intersection.size();
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if (N == 0)
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{
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return INTERSECT_NONE;
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}
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// Get rid of duplicated points
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int Nstride = N;
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cv::AutoBuffer<float, 100> distPt(N * N);
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cv::AutoBuffer<int> ptDistRemap(N);
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for (int i = 0; i < N; ++i)
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{
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const Point2f pt0 = intersection[i];
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ptDistRemap[i] = i;
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for (int j = i + 1; j < N; )
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{
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const Point2f pt1 = intersection[j];
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float d2 = normL2Sqr<float>(pt1 - pt0);
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if(d2 <= samePointEps)
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{
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if (j < N - 1)
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intersection[j] = intersection[N - 1];
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N--;
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continue;
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}
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distPt[i*Nstride + j] = d2;
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++j;
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}
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}
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while (N > 8) // we still have duplicate points after samePointEps threshold (eliminate closest points)
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{
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int minI = 0;
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int minJ = 1;
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float minD = distPt[1];
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for (int i = 0; i < N - 1; ++i)
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{
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float* pDist = distPt.data() + Nstride * ptDistRemap[i];
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for (int j = i + 1; j < N; ++j)
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{
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float d = pDist[ptDistRemap[j]];
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if (d < minD)
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{
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minD = d;
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minI = i;
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minJ = j;
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}
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}
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}
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CV_Assert(fabs(normL2Sqr<float>(intersection[minI] - intersection[minJ]) - minD) < 1e-6); // ptDistRemap is not corrupted
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// drop minJ point
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if (minJ < N - 1)
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{
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intersection[minJ] = intersection[N - 1];
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ptDistRemap[minJ] = ptDistRemap[N - 1];
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}
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N--;
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}
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// order points
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for (int i = 0; i < N - 1; ++i)
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{
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Point2f diffI = intersection[i + 1] - intersection[i];
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for (int j = i + 2; j < N; ++j)
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{
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Point2f diffJ = intersection[j] - intersection[i];
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if (diffI.cross(diffJ) < 0)
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{
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std::swap(intersection[i + 1], intersection[j]);
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diffI = diffJ;
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}
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}
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}
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intersection.resize(N);
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Mat(intersection).copyTo(intersectingRegion);
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return ret;
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}
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} // end namespace
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