Function FillConvexPoly

deps/opencv/modules/core/src/drawing.cpp:1079–1233

filling convex polygon. v - array of vertices, ntps - number of points */

/* filling convex polygon. v - array of vertices, ntps - number of points */
static void
FillConvexPoly( Mat& img, const Point2l* v, int npts, const void* color, int line_type, int shift )
{
    struct
    {
        int idx, di;
        int64 x, dx;
        int ye;
    }
    edge[2];

    int delta = 1 << shift >> 1;
    int i, y, imin = 0, left = 0, right = 1;
    int edges = npts;
    int64 xmin, xmax, ymin, ymax;
    uchar* ptr = img.data;
    Size size = img.size();
    int pix_size = (int)img.elemSize();
    Point2l p0;
    int delta1, delta2;

    if( line_type < CV_AA )
        delta1 = delta2 = XY_ONE >> 1;
    else
        delta1 = XY_ONE - 1, delta2 = 0;

    p0 = v[npts - 1];
    p0.x <<= XY_SHIFT - shift;
    p0.y <<= XY_SHIFT - shift;

    assert( 0 <= shift && shift <= XY_SHIFT );
    xmin = xmax = v[0].x;
    ymin = ymax = v[0].y;

    for( i = 0; i < npts; i++ )
    {
        Point2l p = v[i];
        if( p.y < ymin )
        {
            ymin = p.y;
            imin = i;
        }

        ymax = std::max( ymax, p.y );
        xmax = std::max( xmax, p.x );
        xmin = MIN( xmin, p.x );

        p.x <<= XY_SHIFT - shift;
        p.y <<= XY_SHIFT - shift;

        if( line_type <= 8 )
        {
            if( shift == 0 )
            {
                Point pt0, pt1;
                pt0.x = (int)(p0.x >> XY_SHIFT);
                pt0.y = (int)(p0.y >> XY_SHIFT);
                pt1.x = (int)(p.x >> XY_SHIFT);