text: // Copyright 2009-2021 Intel Corporation
  // SPDX-License-Identifier: Apache-2.0
  
  #pragma once
  
  #include "distribution1d.h"
  
  namespace embree
  {
    /*! 2D probability distribution. The probability distribution
     *  function (PDF) can be initialized with arbitrary data and be
     *  sampled. */
    class Distribution2D
    {
    public:
  
      /*! Default construction. */
      Distribution2D();
  
      /*! Construction from 2D distribution array f. */
      Distribution2D(const float* f, const size_t width, const size_t height);
  
      /*! Initialized the PDF and CDF arrays. */
      void init(const float* f, const size_t width, const size_t height);
  
    public:
  
      /*! Draws a sample from the distribution. \param u is a pair of
       *  random numbers to use for sampling */
      Vec2f sample(const Vec2f& u) const;
  
      /*! Returns the probability density a sample would be drawn from
       *  location p. */
      float pdf(const Vec2f& p) const;
  
      size_t width;            //!< Number of elements in x direction
      size_t height;           //!< Number of elements in y direction
    private:
      Distribution1D yDist;    //!< Distribution to select between rows
      std::vector<Distribution1D> xDists;  //!< One 1D Distribution per row
    };
  }
  
  