Random number generator (Drawing colorful random lines)

class RNG - Random number generator.


RNG::next - Returns the next random number.
RNG::operator T - Returns the next random number of the specified type.

RNG::operator uchar()
RNG::operator ushort()
RNG::operator int()
RNG::operator unsigned int()
RNG::operator float()
RNG::operator double()

RNG::uniform - Returns the next random number sampled from the uniform distribution.

float RNG::uniform(float a, float b)
double RNG::uniform(double a, double b)

RNG::gaussian - Returns the next random number sampled from the Gaussian distribution.

double RNG::gaussian(double sigma)

RNG::fill - Fills arrays with random numbers.

void RNG::fill(InputOutputArray mat, int distType, InputArray a, InputArray b, bool saturateRange=false )

Example:
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RNG rng;

// always produces 0
double a = rng.uniform(0, 1);

// produces double from [0, 1)
double a1 = rng.uniform((double)0, (double)1);

// produces float from [0, 1)
double b = rng.uniform(0.f, 1.f);

// produces double from [0, 1)
double c = rng.uniform(0., 1.);

// may cause compiler error because of ambiguity:
//  RNG::uniform(0, (int)0.999999)? or RNG::uniform((double)0, 0.99999)?
double d = rng.uniform(0, 0.999999);

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The code provided below is slight modification of code given in OpenCV documentation.

Example 1: ( Drawing Colorful Random Lines )

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#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include <iostream>
#include <stdio.h>
#include <stdlib.h>

using namespace cv;
using namespace std;

void Drawing_Random_Lines( Mat image, char* window_name, RNG rng, int NumOfLines, int windowHeight, int windowWidth );
static Scalar randomColor( RNG& rng );

int main( )
{    
    int windowHeight = 480, windowWidth=640;
    Mat image = Mat::zeros( windowHeight, windowWidth, CV_8UC3 );
    namedWindow( "Source", CV_WINDOW_AUTOSIZE );
    int n=1;
    while(1)
    {
    RNG rng(n);
    Drawing_Random_Lines(image, "Source", rng, 5, windowHeight, windowWidth);    
    imshow( "Source", image );
    waitKey(100);
    n++;
    }

    return(0);
}

void Drawing_Random_Lines( Mat image, char* window_name, RNG rng, int NumOfLines, int windowHeight, int windowWidth )
{
    int lineType = 8;
    Point pt1, pt2;

    for( int i = 0; i < NumOfLines; i++ )
    {
        pt1.x = rng.uniform( 0, windowWidth );
        pt1.y = rng.uniform( 0, windowHeight );
        pt2.x = rng.uniform( 0, windowWidth );
        pt2.y = rng.uniform( 0, windowHeight );

        line( image, pt1, pt2, randomColor(rng), rng.uniform(1, 10), 8 );
        imshow( window_name, image );
    }
}

static Scalar randomColor( RNG& rng )
{
    int icolor = (unsigned) rng;
    return Scalar( icolor&255, (icolor>>8)&255, (icolor>>16)&255 );
}

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Example 2: ( Drawing Colorful Random Lines )

-------------

#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include <iostream>
#include <stdio.h>
#include <stdlib.h>

using namespace cv;
using namespace std;

void Drawing_Random_Lines( Mat image, char* window_name, RNG rng, int NumOfLines, int windowHeight, int windowWidth );
static Scalar randomColor( RNG& rng );

int main( )
{   
    int windowHeight = 480, windowWidth=640;
    Mat image = Mat::zeros( windowHeight, windowWidth, CV_8UC3 );
    namedWindow( "Source", CV_WINDOW_AUTOSIZE );
    int n=1;
    while(1)
    {
    RNG rng(n);
    Drawing_Random_Lines(image, "Source", rng, n, windowHeight, windowWidth);   
    imshow( "Source", image );
    waitKey(100);
    n++;
    }

    return(0);
}

void Drawing_Random_Lines( Mat image, char* window_name, RNG rng, int NumOfLines, int windowHeight, int windowWidth )
{
    int lineType = 8;
    Point pt1, pt2;

    for( int i = 0; i < NumOfLines; i++ )
    {
        pt1.x = rng.uniform( 0, windowWidth );
        pt1.y = rng.uniform( 0, windowHeight );
        pt2.x = rng.uniform( 0, windowWidth );
        pt2.y = rng.uniform( 0, windowHeight );

        line( image, pt1, pt2, randomColor(rng), rng.uniform(1, 10), 8 );
        imshow( window_name, image );
    }
}

static Scalar randomColor( RNG& rng )
{
    int icolor = (unsigned) rng;
    return Scalar( icolor&255, (icolor>>8)&255, (icolor>>16)&255 );
}

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Result: