examples

Toy examples in single C files.
git clone git://henryandlizzy.uk/examples
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cie-1931.cpp (1973B)

      1 #include <cmath>
      2 #include <iostream>
      3 #include <sstream>
      4 
      5 inline double gaussian(double x, double a, double u, double s1, double s2) {
      6   double t = (x - u) / (x < u ? s1 : s2);
      7   return a * exp(-(t * t) / 2);
      8 }
      9 
     10 struct XYZ
     11 {
     12 	double x = 0, y = 0, z = 0;
     13 
     14 	XYZ() = default;
     15 	XYZ(double _x, double _y, double _z)
     16 	:	x(_x)
     17 	,	y(_y)
     18 	,	z(_z)
     19 	{}
     20 
     21 	XYZ(double w)
     22 	:	x(gaussian(w,  1.056, 599.8, 37.9, 31.0) + gaussian(w,  0.362, 442.0, 16.0, 26.7) + gaussian(w, -0.065, 501.1, 20.4, 26.2))
     23 	,	y(gaussian(w,  0.821, 568.8, 46.9, 40.5) + gaussian(w,  0.286, 530.9, 16.3, 31.1))
     24 	,	z(gaussian(w,  1.217, 437.0, 11.8, 36.0) + gaussian(w,  0.681, 459.0, 26.0, 13.8))
     25 	{}
     26 
     27 	XYZ operator *(double mult) const
     28 	{
     29 		return XYZ{x*mult, y*mult, z*mult};
     30 	}
     31 	XYZ& operator +=(XYZ rhs)
     32 	{
     33 		x += rhs.x;
     34 		y += rhs.y;
     35 		z += rhs.z;
     36 		return *this;
     37 	}
     38 	double sum(void) const
     39 	{
     40 		return x + y + z;
     41 	}
     42 };
     43 
     44 struct XYZ xyzFromWavelength(double) {
     45   struct XYZ color; // TODO
     46   return color;
     47 }
     48 
     49 struct XYZ xyzFromWavelengthDistribution(double x, double s)
     50 {
     51 	struct XYZ color;
     52 	double delta = 0.1;
     53 
     54 	for (double l = 380; l <= 780; l += delta)
     55 		color += xyzFromWavelength(l) *gaussian(l, 1, x, s, s);
     56 
     57 	return color * delta;
     58 }
     59 
     60 int main(int argc, char* argv[])
     61 {
     62 /**/
     63 	if (2 > argc || argc > 3)
     64 	{
     65 		std::cerr << "cie-1931 wavelength [spread]\n";
     66 		return 1;
     67 	}
     68 
     69 	double x[2];
     70 
     71 	for (int i = 1; i < argc; ++i)
     72 	{
     73 		std::string num(argv[i]);
     74 		std::istringstream ss(num);
     75 
     76 		if (not (ss >> x[i-1]))
     77 		{
     78 			std::cerr << "Wavelength must be in nanometers\n";
     79 			return 1;
     80 		}
     81 	}
     82 
     83 	struct XYZ xyz;
     84 	if (argc == 2)
     85 	{
     86 		xyz = xyzFromWavelength(x[0]);
     87 		std::cout << x[0] << "nm\n\n";
     88 	} else
     89 	{
     90 		xyz = xyzFromWavelengthDistribution(x[0], x[1]);
     91 		std::cout << x[0] << "nm +-(" << x[1] << ")\n\n";
     92 	}
     93 /**/
     94 
     95 	std::cout << "X: " << xyz.x << "\nY: " << xyz.y << "\nZ: " << xyz.z << "\n\n";
     96 
     97 	double sum = xyz.sum();
     98 
     99 	std::cout << "x: " << (xyz.x / sum) << "\ny: " << (xyz.y / sum) << "\n";
    100 
    101 	return 0;
    102 }