.. _program_listing_file_Src_GraphicsEngineOpenGL_util_RandomNumbers.cpp:

Program Listing for File RandomNumbers.cpp
==========================================

|exhale_lsh| :ref:`Return to documentation for file <file_Src_GraphicsEngineOpenGL_util_RandomNumbers.cpp>` (``Src/GraphicsEngineOpenGL/util/RandomNumbers.cpp``)

.. |exhale_lsh| unicode:: U+021B0 .. UPWARDS ARROW WITH TIP LEFTWARDS

.. code-block:: cpp

   #include "util/RandomNumbers.hpp"
   
   #include "hostDevice/bindings.hpp"
   #include "hostDevice/host_device_shared.hpp"
   
   #include "hostDevice/GlobalValues.hpp"
   #include <random>
   
   RandomNumbers::RandomNumbers()
   {
       generate_random_numbers();
   
       glGenTextures(1, &random_number_id);
       glBindTexture(GL_TEXTURE_2D, random_number_id);
       // i think we won't need nearest option; so stick to linear
       glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
       glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
       glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
       glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
       // assuming full HD will be maximum resolution
       glTexImage2D(
         GL_TEXTURE_2D, 0, GL_RGBA32F, MAX_RESOLUTION_X, MAX_RESOLUTION_Y, 0, GL_RGBA, GL_FLOAT, random_number_data.get());
       glBindTexture(GL_TEXTURE_2D, 0);
   }
   
   void RandomNumbers::read()
   {
       glActiveTexture(GL_TEXTURE0 + (GLenum)RANDOM_NUMBERS_SLOT);
       glBindTexture(GL_TEXTURE_2D, random_number_id);
   }
   
   void RandomNumbers::generate_random_numbers()
   {
       random_number_data = std::shared_ptr<GLfloat[]>(new GLfloat[MAX_RESOLUTION_X * MAX_RESOLUTION_Y * 4]);
       std::mt19937_64 gen64(25121995);
       std::uniform_real_distribution<float> dis(0, 1);
   
       for (int i = 0; i < MAX_RESOLUTION_X; i++) {
           for (int k = 0; k < MAX_RESOLUTION_Y; k++) {
               const GLfloat random_offset[4] = { dis(gen64), dis(gen64), dis(gen64), dis(gen64) };
   
               GLuint index = (MAX_RESOLUTION_Y * i + k) * 4;
   
               *(random_number_data.get() + index) = random_offset[0];
               *(random_number_data.get() + index + 1) = random_offset[1];
               *(random_number_data.get() + index + 2) = random_offset[2];
               *(random_number_data.get() + index + 3) = random_offset[3];
           }
       }
   }
   
   RandomNumbers::~RandomNumbers() { glDeleteTextures(1, &random_number_id); }