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mandelbrot.cpp
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mandelbrot.cpp
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#include <array>
#include <cmath>
#ifdef PNG_8BIT
using png_array_type = uint8_t;
inline void encode_color(png_array_type& px, int count, int max_count)
{
px = count & 15;
}
#else
using png_array_type = uint32_t;
inline void encode_color(png_array_type& px, int count, int max_count)
{
px = color_mapping[count & 15];
}
#endif
// Function to draw mandelbrot set
template <int DimX, int DimY, int MaxCount>
std::array<png_array_type, DimX * DimY>
fractal(double left, double top, double xside, double yside)
{
std::array<png_array_type, DimX * DimY> bitmap {};
// setting up the xscale and yscale
const double xscale = xside / DimX;
const double yscale = yside / DimY;
// scanning every point in that rectangular area.
// Each point represents a Complex number (x + yi).
// Iterate that complex number
for (int y = 0; y < DimY / 2; y++)
for (int x = 0; x < DimX; x++)
{
double c_real = x * xscale + left;
double c_imag = y * yscale + top;
double z_real = 0;
double z_imag = 0;
int count = 0;
// Calculate whether c(c_real + c_imag) belongs
// to the Mandelbrot set or not and draw a pixel
// at coordinates (x, y) accordingly
// If you reach the Maximum number of iterations
// and If the distance from the origin is
// greater than 2 exit the loop
#pragma GCC unroll 4
while ((z_real * z_real + z_imag * z_imag < 4)
&& (count < MaxCount))
{
// Calculate Mandelbrot function
// z = z*z + c where z is a complex number
double tempx =
z_real * z_real - z_imag * z_imag + c_real;
z_imag = 2 * z_real * z_imag + c_imag;
z_real = tempx;
count++;
}
encode_color(bitmap[x + y * DimX], count, MaxCount);
}
for (int y = 0; y < DimY / 2; y++) {
memcpy(&bitmap[(DimY-1 - y) * DimX], &bitmap[y * DimX], DimX * sizeof(png_array_type));
}
return bitmap;
}