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opencv/modules/3d/src/convhull.cpp
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Alexander Smorkalov aac582119c Merge pull request #29101 from asmorkalov:as/geometry_module
Moved geometry transformations from imgproc to 3d, future geometry module #29101

The first step of 2d geometry operations migration to the future geometry module.
I created 2d.hpp to isolate the moved functions for now. I propose to create geometry.hpp when the module is renamed and include all things there.

OpenCV contrib: https://github.com/opencv/opencv_contrib/pull/4126

### Pull Request Readiness Checklist

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
- [ ] The PR is proposed to the proper branch
- [ ] There is a reference to the original bug report and related work
- [ ] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
      Patch to opencv_extra has the same branch name.
- [ ] The feature is well documented and sample code can be built with the project CMake
2026-05-28 21:09:52 +03:00

496 lines
15 KiB
C++

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#include "precomp.hpp"
#include <iostream>
namespace cv
{
template<typename _Tp, typename _DotTp>
static int Sklansky_( Point_<_Tp>** array, int start, int end, int* stack, int nsign, int sign2 )
{
int incr = end > start ? 1 : -1;
// prepare first triangle
int pprev = start, pcur = pprev + incr, pnext = pcur + incr;
int stacksize = 3;
if( start == end ||
(array[start]->x == array[end]->x &&
array[start]->y == array[end]->y) )
{
stack[0] = start;
return 1;
}
stack[0] = pprev;
stack[1] = pcur;
stack[2] = pnext;
end += incr; // make end = afterend
while( pnext != end )
{
// check the angle p1,p2,p3
_Tp cury = array[pcur]->y;
_Tp nexty = array[pnext]->y;
_Tp by = nexty - cury;
if( CV_SIGN( by ) != nsign )
{
Vec<_Tp, 2> a(array[pcur]->x - array[pprev]->x, cury - array[pprev]->y);
Vec<_Tp, 2> b(array[pnext]->x - array[pcur]->x, by);
if (std::is_floating_point<_Tp>::value)
{
a = normalize(a);
b = normalize(b);
}
_DotTp convexity = (_DotTp)a[1]*b[0] - (_DotTp)a[0]*b[1]; // if >0 then convex angle
if( CV_SIGN( convexity ) == sign2 && (a[0] != 0 || a[1] != 0) )
{
pprev = pcur;
pcur = pnext;
pnext += incr;
stack[stacksize] = pnext;
stacksize++;
}
else
{
if( pprev == start )
{
pcur = pnext;
stack[1] = pcur;
pnext += incr;
stack[2] = pnext;
}
else
{
stack[stacksize-2] = pnext;
pcur = pprev;
pprev = stack[stacksize-4];
stacksize--;
}
}
}
else
{
pnext += incr;
stack[stacksize-1] = pnext;
}
}
return --stacksize;
}
template<typename _Tp>
struct CHullCmpPoints
{
bool operator()(const Point_<_Tp>* p1, const Point_<_Tp>* p2) const
{
if( p1->x != p2->x )
return p1->x < p2->x;
if( p1->y != p2->y )
return p1->y < p2->y;
return p1 < p2;
}
};
void convexHull( InputArray _points, OutputArray _hull, bool clockwise, bool returnPoints )
{
CV_INSTRUMENT_REGION();
CV_Assert(_points.getObj() != _hull.getObj());
Mat points = _points.getMat();
int i, total = points.checkVector(2), depth = points.depth(), nout = 0;
int miny_ind = 0, maxy_ind = 0;
CV_Assert(total >= 0 && (depth == CV_32F || depth == CV_32S));
if( total == 0 )
{
_hull.release();
return;
}
returnPoints = !_hull.fixedType() ? returnPoints : _hull.type() != CV_32S;
bool is_float = depth == CV_32F;
AutoBuffer<Point*> _pointer(total);
AutoBuffer<int> _stack(total + 2), _hullbuf(total);
Point** pointer = _pointer.data();
Point2f** pointerf = (Point2f**)pointer;
Point* data0 = points.ptr<Point>();
int* stack = _stack.data();
int* hullbuf = _hullbuf.data();
CV_Assert(points.isContinuous());
for( i = 0; i < total; i++ )
pointer[i] = &data0[i];
// sort the point set by x-coordinate, find min and max y
if( !is_float )
{
std::sort(pointer, pointer + total, CHullCmpPoints<int>());
for( i = 1; i < total; i++ )
{
int y = pointer[i]->y;
if( pointer[miny_ind]->y > y )
miny_ind = i;
if( pointer[maxy_ind]->y < y )
maxy_ind = i;
}
}
else
{
std::sort(pointerf, pointerf + total, CHullCmpPoints<float>());
for( i = 1; i < total; i++ )
{
float y = pointerf[i]->y;
if( pointerf[miny_ind]->y > y )
miny_ind = i;
if( pointerf[maxy_ind]->y < y )
maxy_ind = i;
}
}
if( pointer[0]->x == pointer[total-1]->x &&
pointer[0]->y == pointer[total-1]->y )
{
hullbuf[nout++] = 0;
}
else
{
// upper half
int *tl_stack = stack;
int tl_count = !is_float ?
Sklansky_<int, int64>( pointer, 0, maxy_ind, tl_stack, -1, 1) :
Sklansky_<float, double>( pointerf, 0, maxy_ind, tl_stack, -1, 1);
int *tr_stack = stack + tl_count;
int tr_count = !is_float ?
Sklansky_<int, int64>( pointer, total-1, maxy_ind, tr_stack, -1, -1) :
Sklansky_<float, double>( pointerf, total-1, maxy_ind, tr_stack, -1, -1);
// gather upper part of convex hull to output
if( !clockwise )
{
std::swap( tl_stack, tr_stack );
std::swap( tl_count, tr_count );
}
for( i = 0; i < tl_count-1; i++ )
hullbuf[nout++] = tl_stack[i];
for( i = tr_count - 1; i > 0; i-- )
hullbuf[nout++] = tr_stack[i];
int stop_idx = tr_count > 2 ? tr_stack[1] : tl_count > 2 ? tl_stack[tl_count - 2] : -1;
// lower half
int *bl_stack = stack;
int bl_count = !is_float ?
Sklansky_<int, int64>( pointer, 0, miny_ind, bl_stack, 1, -1) :
Sklansky_<float, double>( pointerf, 0, miny_ind, bl_stack, 1, -1);
int *br_stack = stack + bl_count;
int br_count = !is_float ?
Sklansky_<int, int64>( pointer, total-1, miny_ind, br_stack, 1, 1) :
Sklansky_<float, double>( pointerf, total-1, miny_ind, br_stack, 1, 1);
if( clockwise )
{
std::swap( bl_stack, br_stack );
std::swap( bl_count, br_count );
}
if( stop_idx >= 0 )
{
int check_idx = bl_count > 2 ? bl_stack[1] :
bl_count + br_count > 2 ? br_stack[2-bl_count] : -1;
if( check_idx == stop_idx || (check_idx >= 0 &&
pointer[check_idx]->x == pointer[stop_idx]->x &&
pointer[check_idx]->y == pointer[stop_idx]->y) )
{
// if all the points lie on the same line, then
// the bottom part of the convex hull is the mirrored top part
// (except the exteme points).
bl_count = MIN( bl_count, 2 );
br_count = MIN( br_count, 2 );
}
}
for( i = 0; i < bl_count-1; i++ )
hullbuf[nout++] = bl_stack[i];
for( i = br_count-1; i > 0; i-- )
hullbuf[nout++] = br_stack[i];
if (!returnPoints)
{
// Try keep monotonous indices in case of self-intersection.
for (i = 0; i < nout; ++i)
{
auto prev = pointer[hullbuf[(i == 0 ? nout : i) - 1]];
auto next = pointer[hullbuf[(i + 1) % nout]];
auto cur = pointer[hullbuf[i]];
if ((prev < cur && cur < next) || (prev > cur && cur > next))
{
continue;
}
for (int j = hullbuf[i] + 1; j < total; ++j)
{
cur = pointer[j];
if (*pointer[hullbuf[i]] == *cur)
{
if ((prev < cur && cur < next) || (prev > cur && cur > next))
{
hullbuf[i] = j;
break;
}
}
else
break;
}
}
}
for (i = 0; i < nout; ++i)
{
hullbuf[i] = int(pointer[hullbuf[i]] - data0);
}
// try to make the convex hull indices form
// an ascending or descending sequence by the cyclic
// shift of the output sequence.
if( nout >= 3 )
{
int min_idx = 0, max_idx = 0, lt = 0;
for( i = 1; i < nout; i++ )
{
int idx = hullbuf[i];
lt += hullbuf[i-1] < idx;
if( lt > 1 && lt <= i-2 )
break;
if( idx < hullbuf[min_idx] )
min_idx = i;
if( idx > hullbuf[max_idx] )
max_idx = i;
}
int mmdist = std::abs(max_idx - min_idx);
if( (mmdist == 1 || mmdist == nout-1) && (lt <= 1 || lt >= nout-2) )
{
int ascending = (max_idx + 1) % nout == min_idx;
int i0 = ascending ? min_idx : max_idx, j = i0;
if( i0 > 0 )
{
for( i = 0; i < nout; i++ )
{
int curr_idx = stack[i] = hullbuf[j];
int next_j = j+1 < nout ? j+1 : 0;
int next_idx = hullbuf[next_j];
if( i < nout-1 && (ascending != (curr_idx < next_idx)) )
break;
j = next_j;
}
if( i == nout )
memcpy(hullbuf, stack, nout*sizeof(hullbuf[0]));
}
}
}
}
if( !returnPoints )
Mat(nout, 1, CV_32S, hullbuf).copyTo(_hull);
else
{
_hull.create(nout, 1, CV_MAKETYPE(depth, 2));
Mat hull = _hull.getMat();
size_t step = !hull.isContinuous() ? hull.step[0] : sizeof(Point);
for( i = 0; i < nout; i++ )
*(Point*)(hull.ptr() + i*step) = data0[hullbuf[i]];
}
}
void convexityDefects( InputArray _points, InputArray _hull, OutputArray _defects )
{
CV_INSTRUMENT_REGION();
Mat points = _points.getMat();
int i, j = 0, npoints = points.checkVector(2, CV_32S);
CV_Assert( npoints >= 0 );
if( npoints <= 3 )
{
_defects.release();
return;
}
Mat hull = _hull.getMat();
int hpoints = hull.checkVector(1, CV_32S);
CV_Assert( hpoints > 0 );
const Point* ptr = points.ptr<Point>();
const int* hptr = hull.ptr<int>();
std::vector<Vec4i> defects;
if ( hpoints < 3 ) //if hull consists of one or two points, contour is always convex
{
_defects.release();
return;
}
// 1. recognize co-orientation of the contour and its hull
bool rev_orientation = ((hptr[1] > hptr[0]) + (hptr[2] > hptr[1]) + (hptr[0] > hptr[2])) != 2;
// 2. cycle through points and hull, compute defects
int hcurr = hptr[rev_orientation ? 0 : hpoints-1];
CV_Assert( 0 <= hcurr && hcurr < npoints );
int increasing_idx = -1;
for( i = 0; i < hpoints; i++ )
{
int hnext = hptr[rev_orientation ? hpoints - i - 1 : i];
CV_Assert( 0 <= hnext && hnext < npoints );
Point pt0 = ptr[hcurr], pt1 = ptr[hnext];
if( increasing_idx < 0 )
increasing_idx = !(hcurr < hnext);
else if( increasing_idx != (hcurr < hnext))
{
CV_Error(Error::StsBadArg,
"The convex hull indices are not monotonous, which can be in the case when the input contour contains self-intersections");
}
double dx0 = pt1.x - pt0.x;
double dy0 = pt1.y - pt0.y;
double scale = dx0 == 0 && dy0 == 0 ? 0. : 1./std::sqrt(dx0*dx0 + dy0*dy0);
int defect_deepest_point = -1;
double defect_depth = 0;
bool is_defect = false;
j=hcurr;
for(;;)
{
// go through points to achieve next hull point
j++;
j &= j >= npoints ? 0 : -1;
if( j == hnext )
break;
// compute distance from current point to hull edge
double dx = ptr[j].x - pt0.x;
double dy = ptr[j].y - pt0.y;
double dist = fabs(-dy0*dx + dx0*dy) * scale;
if( dist > defect_depth )
{
defect_depth = dist;
defect_deepest_point = j;
is_defect = true;
}
}
if( is_defect )
{
int idepth = cvRound(defect_depth*256);
defects.push_back(Vec4i(hcurr, hnext, defect_deepest_point, idepth));
}
hcurr = hnext;
}
Mat(defects).copyTo(_defects);
}
template<typename _Tp>
static bool isContourConvex_( const Point_<_Tp>* p, int n )
{
Point_<_Tp> prev_pt = p[(n-2+n) % n];
Point_<_Tp> cur_pt = p[n-1];
_Tp dx0 = cur_pt.x - prev_pt.x;
_Tp dy0 = cur_pt.y - prev_pt.y;
int orientation = 0;
for( int i = 0; i < n; i++ )
{
_Tp dxdy0, dydx0;
_Tp dx, dy;
prev_pt = cur_pt;
cur_pt = p[i];
dx = cur_pt.x - prev_pt.x;
dy = cur_pt.y - prev_pt.y;
dxdy0 = dx * dy0;
dydx0 = dy * dx0;
// find orientation
// orient = -dy0 * dx + dx0 * dy;
// orientation |= (orient > 0) ? 1 : 2;
orientation |= (dydx0 > dxdy0) ? 1 : ((dydx0 < dxdy0) ? 2 : 3);
if( orientation == 3 )
return false;
dx0 = dx;
dy0 = dy;
}
return true;
}
bool isContourConvex( InputArray _contour )
{
Mat contour = _contour.getMat();
int total = contour.checkVector(2), depth = contour.depth();
CV_Assert(total >= 0 && (depth == CV_32F || depth == CV_32S));
if( total == 0 )
return false;
return depth == CV_32S ?
isContourConvex_(contour.ptr<Point>(), total ) :
isContourConvex_(contour.ptr<Point2f>(), total );
}
}