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442 lines
14 KiB
C++
442 lines
14 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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// Intel License Agreement
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// For Open Source Computer Vision Library
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//
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// Copyright (C) 2000, Intel Corporation, all rights reserved.
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// Third party copyrights are property of their respective owners.
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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 Intel Corporation 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 Intel Corporation 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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typedef struct
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{
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int bottom;
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int left;
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float height;
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float width;
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float base_a;
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float base_b;
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}
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icvMinAreaState;
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#define CV_CALIPERS_MAXHEIGHT 0
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#define CV_CALIPERS_MINAREARECT 1
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#define CV_CALIPERS_MAXDIST 2
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/*F///////////////////////////////////////////////////////////////////////////////////////
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// Name: icvRotatingCalipers
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// Purpose:
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// Rotating calipers algorithm with some applications
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//
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// Context:
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// Parameters:
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// points - convex hull vertices ( any orientation )
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// n - number of vertices
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// mode - concrete application of algorithm
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// can be CV_CALIPERS_MAXDIST or
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// CV_CALIPERS_MINAREARECT
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// left, bottom, right, top - indexes of extremal points
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// out - output info.
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// In case CV_CALIPERS_MAXDIST it points to float value -
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// maximal height of polygon.
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// In case CV_CALIPERS_MINAREARECT
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// ((CvPoint2D32f*)out)[0] - corner
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// ((CvPoint2D32f*)out)[1] - vector1
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// ((CvPoint2D32f*)out)[0] - corner2
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//
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// ^
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// |
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// vector2 |
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// |
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// |____________\
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// corner /
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// vector1
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//
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// Returns:
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// Notes:
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//F*/
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/* we will use usual cartesian coordinates */
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static void
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icvRotatingCalipers( CvPoint2D32f* points, int n, int mode, float* out )
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{
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float minarea = FLT_MAX;
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float max_dist = 0;
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char buffer[32];
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int i, k;
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CvPoint2D32f* vect = (CvPoint2D32f*)cvAlloc( n * sizeof(vect[0]) );
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float* inv_vect_length = (float*)cvAlloc( n * sizeof(inv_vect_length[0]) );
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int left = 0, bottom = 0, right = 0, top = 0;
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int seq[4] = { -1, -1, -1, -1 };
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/* rotating calipers sides will always have coordinates
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(a,b) (-b,a) (-a,-b) (b, -a)
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*/
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/* this is a first base bector (a,b) initialized by (1,0) */
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float orientation = 0;
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float base_a;
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float base_b = 0;
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float left_x, right_x, top_y, bottom_y;
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CvPoint2D32f pt0 = points[0];
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left_x = right_x = pt0.x;
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top_y = bottom_y = pt0.y;
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for( i = 0; i < n; i++ )
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{
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double dx, dy;
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if( pt0.x < left_x )
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left_x = pt0.x, left = i;
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if( pt0.x > right_x )
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right_x = pt0.x, right = i;
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if( pt0.y > top_y )
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top_y = pt0.y, top = i;
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if( pt0.y < bottom_y )
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bottom_y = pt0.y, bottom = i;
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CvPoint2D32f pt = points[(i+1) & (i+1 < n ? -1 : 0)];
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dx = pt.x - pt0.x;
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dy = pt.y - pt0.y;
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vect[i].x = (float)dx;
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vect[i].y = (float)dy;
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inv_vect_length[i] = (float)(1./sqrt(dx*dx + dy*dy));
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pt0 = pt;
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}
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//cvbInvSqrt( inv_vect_length, inv_vect_length, n );
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/* find convex hull orientation */
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{
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double ax = vect[n-1].x;
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double ay = vect[n-1].y;
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for( i = 0; i < n; i++ )
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{
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double bx = vect[i].x;
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double by = vect[i].y;
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double convexity = ax * by - ay * bx;
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if( convexity != 0 )
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{
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orientation = (convexity > 0) ? 1.f : (-1.f);
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break;
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}
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ax = bx;
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ay = by;
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}
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assert( orientation != 0 );
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}
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base_a = orientation;
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/*****************************************************************************************/
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/* init calipers position */
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seq[0] = bottom;
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seq[1] = right;
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seq[2] = top;
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seq[3] = left;
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/*****************************************************************************************/
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/* Main loop - evaluate angles and rotate calipers */
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/* all of edges will be checked while rotating calipers by 90 degrees */
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for( k = 0; k < n; k++ )
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{
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/* sinus of minimal angle */
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/*float sinus;*/
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/* compute cosine of angle between calipers side and polygon edge */
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/* dp - dot product */
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float dp0 = base_a * vect[seq[0]].x + base_b * vect[seq[0]].y;
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float dp1 = -base_b * vect[seq[1]].x + base_a * vect[seq[1]].y;
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float dp2 = -base_a * vect[seq[2]].x - base_b * vect[seq[2]].y;
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float dp3 = base_b * vect[seq[3]].x - base_a * vect[seq[3]].y;
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float cosalpha = dp0 * inv_vect_length[seq[0]];
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float maxcos = cosalpha;
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/* number of calipers edges, that has minimal angle with edge */
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int main_element = 0;
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/* choose minimal angle */
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cosalpha = dp1 * inv_vect_length[seq[1]];
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maxcos = (cosalpha > maxcos) ? (main_element = 1, cosalpha) : maxcos;
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cosalpha = dp2 * inv_vect_length[seq[2]];
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maxcos = (cosalpha > maxcos) ? (main_element = 2, cosalpha) : maxcos;
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cosalpha = dp3 * inv_vect_length[seq[3]];
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maxcos = (cosalpha > maxcos) ? (main_element = 3, cosalpha) : maxcos;
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/*rotate calipers*/
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{
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//get next base
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int pindex = seq[main_element];
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float lead_x = vect[pindex].x*inv_vect_length[pindex];
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float lead_y = vect[pindex].y*inv_vect_length[pindex];
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switch( main_element )
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{
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case 0:
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base_a = lead_x;
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base_b = lead_y;
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break;
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case 1:
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base_a = lead_y;
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base_b = -lead_x;
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break;
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case 2:
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base_a = -lead_x;
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base_b = -lead_y;
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break;
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case 3:
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base_a = -lead_y;
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base_b = lead_x;
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break;
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default: assert(0);
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}
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}
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/* change base point of main edge */
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seq[main_element] += 1;
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seq[main_element] = (seq[main_element] == n) ? 0 : seq[main_element];
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switch (mode)
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{
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case CV_CALIPERS_MAXHEIGHT:
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{
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/* now main element lies on edge alligned to calipers side */
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/* find opposite element i.e. transform */
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/* 0->2, 1->3, 2->0, 3->1 */
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int opposite_el = main_element ^ 2;
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float dx = points[seq[opposite_el]].x - points[seq[main_element]].x;
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float dy = points[seq[opposite_el]].y - points[seq[main_element]].y;
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float dist;
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if( main_element & 1 )
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dist = (float)fabs(dx * base_a + dy * base_b);
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else
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dist = (float)fabs(dx * (-base_b) + dy * base_a);
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if( dist > max_dist )
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max_dist = dist;
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break;
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}
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case CV_CALIPERS_MINAREARECT:
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/* find area of rectangle */
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{
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float height;
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float area;
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/* find vector left-right */
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float dx = points[seq[1]].x - points[seq[3]].x;
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float dy = points[seq[1]].y - points[seq[3]].y;
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/* dotproduct */
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float width = dx * base_a + dy * base_b;
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/* find vector left-right */
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dx = points[seq[2]].x - points[seq[0]].x;
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dy = points[seq[2]].y - points[seq[0]].y;
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/* dotproduct */
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height = -dx * base_b + dy * base_a;
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area = width * height;
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if( area <= minarea )
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{
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float *buf = (float *) buffer;
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minarea = area;
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/* leftist point */
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((int *) buf)[0] = seq[3];
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buf[1] = base_a;
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buf[2] = width;
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buf[3] = base_b;
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buf[4] = height;
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/* bottom point */
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((int *) buf)[5] = seq[0];
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buf[6] = area;
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}
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break;
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}
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} /*switch */
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} /* for */
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switch (mode)
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{
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case CV_CALIPERS_MINAREARECT:
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{
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float *buf = (float *) buffer;
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float A1 = buf[1];
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float B1 = buf[3];
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float A2 = -buf[3];
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float B2 = buf[1];
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float C1 = A1 * points[((int *) buf)[0]].x + points[((int *) buf)[0]].y * B1;
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float C2 = A2 * points[((int *) buf)[5]].x + points[((int *) buf)[5]].y * B2;
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float idet = 1.f / (A1 * B2 - A2 * B1);
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float px = (C1 * B2 - C2 * B1) * idet;
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float py = (A1 * C2 - A2 * C1) * idet;
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out[0] = px;
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out[1] = py;
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out[2] = A1 * buf[2];
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out[3] = B1 * buf[2];
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out[4] = A2 * buf[4];
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out[5] = B2 * buf[4];
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}
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break;
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case CV_CALIPERS_MAXHEIGHT:
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{
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out[0] = max_dist;
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}
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break;
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}
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cvFree( &vect );
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cvFree( &inv_vect_length );
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}
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CV_IMPL CvBox2D
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cvMinAreaRect2( const CvArr* array, CvMemStorage* storage )
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{
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cv::Ptr<CvMemStorage> temp_storage;
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CvBox2D box;
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cv::AutoBuffer<CvPoint2D32f> _points;
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CvPoint2D32f* points;
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memset(&box, 0, sizeof(box));
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int i, n;
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CvSeqReader reader;
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CvContour contour_header;
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CvSeqBlock block;
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CvSeq* ptseq = (CvSeq*)array;
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CvPoint2D32f out[3];
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if( CV_IS_SEQ(ptseq) )
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{
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if( !CV_IS_SEQ_POINT_SET(ptseq) &&
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(CV_SEQ_KIND(ptseq) != CV_SEQ_KIND_CURVE ||
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CV_SEQ_ELTYPE(ptseq) != CV_SEQ_ELTYPE_PPOINT ))
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CV_Error( CV_StsUnsupportedFormat,
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"Input sequence must consist of 2d points or pointers to 2d points" );
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if( !storage )
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storage = ptseq->storage;
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}
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else
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{
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ptseq = cvPointSeqFromMat( CV_SEQ_KIND_GENERIC, array, &contour_header, &block );
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}
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if( storage )
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{
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temp_storage = cvCreateChildMemStorage( storage );
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}
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else
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{
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temp_storage = cvCreateMemStorage(1 << 10);
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}
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ptseq = cvConvexHull2( ptseq, temp_storage, CV_CLOCKWISE, 1 );
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n = ptseq->total;
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_points.allocate(n);
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points = _points;
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cvStartReadSeq( ptseq, &reader );
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if( CV_SEQ_ELTYPE( ptseq ) == CV_32SC2 )
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{
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for( i = 0; i < n; i++ )
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{
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CvPoint pt;
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CV_READ_SEQ_ELEM( pt, reader );
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points[i].x = (float)pt.x;
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points[i].y = (float)pt.y;
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}
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}
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else
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{
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for( i = 0; i < n; i++ )
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{
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CV_READ_SEQ_ELEM( points[i], reader );
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}
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}
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if( n > 2 )
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{
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icvRotatingCalipers( points, n, CV_CALIPERS_MINAREARECT, (float*)out );
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box.center.x = out[0].x + (out[1].x + out[2].x)*0.5f;
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box.center.y = out[0].y + (out[1].y + out[2].y)*0.5f;
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box.size.height = (float)sqrt((double)out[1].x*out[1].x + (double)out[1].y*out[1].y);
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box.size.width = (float)sqrt((double)out[2].x*out[2].x + (double)out[2].y*out[2].y);
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box.angle = (float)atan2( -(double)out[1].y, (double)out[1].x );
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}
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else if( n == 2 )
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{
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box.center.x = (points[0].x + points[1].x)*0.5f;
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box.center.y = (points[0].y + points[1].y)*0.5f;
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double dx = points[1].x - points[0].x;
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double dy = points[1].y - points[0].y;
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box.size.height = (float)sqrt(dx*dx + dy*dy);
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box.size.width = 0;
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box.angle = (float)atan2( -dy, dx );
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}
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else
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{
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if( n == 1 )
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box.center = points[0];
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}
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box.angle = (float)(box.angle*180/CV_PI);
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return box;
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}
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