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#include "precomp.hpp"

using namespace cv;
using namespace cv::cuda;

#if !defined (HAVE_CUDA) || !defined(HAVE_OPENCV_CUDAIMGPROC) || defined (CUDA_DISABLER)

void cv::cuda::createOpticalFlowNeedleMap(const GpuMat&, const GpuMat&, GpuMat&, GpuMat&) { throw_no_cuda(); }

#else

namespace cv { namespace cuda { namespace device
{
    namespace optical_flow
    {
        void NeedleMapAverage_gpu(PtrStepSzf u, PtrStepSzf v, PtrStepSzf u_avg, PtrStepSzf v_avg);
        void CreateOpticalFlowNeedleMap_gpu(PtrStepSzf u_avg, PtrStepSzf v_avg, float* vertex_buffer, float* color_data, float max_flow, float xscale, float yscale);
    }
}}}

void cv::cuda::createOpticalFlowNeedleMap(const GpuMat& u, const GpuMat& v, GpuMat& vertex, GpuMat& colors)
{
    using namespace cv::cuda::device::optical_flow;

    CV_Assert(u.type() == CV_32FC1);
    CV_Assert(v.type() == u.type() && v.size() == u.size());

    const int NEEDLE_MAP_SCALE = 16;

    const int x_needles = u.cols / NEEDLE_MAP_SCALE;
    const int y_needles = u.rows / NEEDLE_MAP_SCALE;

    GpuMat u_avg(y_needles, x_needles, CV_32FC1);
    GpuMat v_avg(y_needles, x_needles, CV_32FC1);

    NeedleMapAverage_gpu(u, v, u_avg, v_avg);

    const int NUM_VERTS_PER_ARROW = 6;

    const int num_arrows = x_needles * y_needles * NUM_VERTS_PER_ARROW;

    vertex.create(1, num_arrows, CV_32FC3);
    colors.create(1, num_arrows, CV_32FC3);

    colors.setTo(Scalar::all(1.0));

    double uMax, vMax;
    cuda::minMax(u_avg, 0, &uMax);
    cuda::minMax(v_avg, 0, &vMax);

    float max_flow = static_cast<float>(std::sqrt(uMax * uMax + vMax * vMax));

    CreateOpticalFlowNeedleMap_gpu(u_avg, v_avg, vertex.ptr<float>(), colors.ptr<float>(), max_flow, 1.0f / u.cols, 1.0f / u.rows);

    cuda::cvtColor(colors, colors, COLOR_HSV2RGB);
}

#endif /* HAVE_CUDA */