119 lines
3 KiB
C++
119 lines
3 KiB
C++
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#include <cmath>
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#include <string>
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#include <vector>
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#include <tuple>
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#include <chrono>
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#include <cassert>
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const int D = 2;
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const int MAX_ITERATION = 200;
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const double XL = - 2.5;
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const double XR = 1.0;
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const double YB = -1.0;
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const double YT = 1.0;
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extern int H;
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extern int W;
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extern unsigned char* RGB;
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inline void dump_tga(int w, int h, unsigned char rgb[], const char *filename) {
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FILE *file_unit;
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unsigned char header1[12] = {0,0,2,0,0,0,0,0,0,0,0,0};
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unsigned char header2[6] = {static_cast<unsigned char>(w%256),
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static_cast<unsigned char>(w/256),
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static_cast<unsigned char>(h%256),
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static_cast<unsigned char>(h/256), 24, 0};
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// Create the file.
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file_unit = fopen(filename, "wb");
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// Write the headers.
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fwrite(header1, sizeof(unsigned char), 12, file_unit);
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fwrite(header2, sizeof(unsigned char), 6, file_unit);
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//Write the image data.
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fwrite(rgb, sizeof(unsigned char), 3*w*h, file_unit);
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// Close the file.
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fclose(file_unit);
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printf("Dump figure to '%s'\n", filename);
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}
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// Computes the value of the point (px, py), which represents the complex
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// number (px + i*py), based on whether it is part of the Mandelbrot set or not
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inline int escape_time(double px, double py, int n) {
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// x and y represent a complex number (x + i*y)
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double x = px;
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double y = py;
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// square both components
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double x2 = x * x;
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double y2 = y * y;
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//// Julia set
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//double cr = -0.8;
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//double ci = 0.156;
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// Mandelbrot set:
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double cr = px;
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double ci = py;
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double xtmp;
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// We need i (number of iteration) after the loop, so don't declare the variable inside the for.
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int i;
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for (i = 0; (x2 + y2) <= 4.0 && i < MAX_ITERATION; i++) {
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xtmp = pow((x*x+y*y), (n/2.0))*cos(n*atan2(y,x)) + cr;
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y = pow((x*x+y*y), (n/2.0))*sin(n*atan2(y,x)) + ci;
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x = xtmp;
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// Update our temp variables
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x2 = x * x;
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y2 = y * y;
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}
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return i;
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}
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// Map a given (x, y) coordinate to the range [XL, XR] [YB, YT]
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inline std::pair<double, double> scale_xy(double x, double y) {
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double xx = XL + (XR - XL)/W * x;
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double yy = YB + (YT - YB)/H * y;
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return {xx, yy};
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}
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// Given an iteration, return a RGB color
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// Ref: https://stackoverflow.com/questions/16500656/which-color-gradient-is-used-to-color-mandelbrot-in-wikipedia
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inline std::tuple<int, int, int> get_color(int n) {
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if(n < MAX_ITERATION && n) {
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int i = n % 16;
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const static std::vector<std::tuple<int, int, int>> colors {
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{66, 30, 15},
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{25, 7, 26},
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{9, 1, 47},
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{4, 4, 73},
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{0, 7, 100},
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{12, 44, 138},
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{24, 82, 177},
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{57, 125, 209},
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{134, 181, 229},
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{211, 236, 248},
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{241, 233, 191},
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{248, 201, 95},
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{255, 170, 0},
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{204, 128, 0},
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{153, 87, 0},
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{106, 52, 3}
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};
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return colors[i];
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}
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return {0, 0, 0};
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}
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std::chrono::microseconds measure_time_taskflow(unsigned);
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std::chrono::microseconds measure_time_omp(unsigned);
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std::chrono::microseconds measure_time_tbb(unsigned);
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