75 lines
2.1 KiB
C++
75 lines
2.1 KiB
C++
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#include <stdint.h>
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#include <cmath>
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#include <cstdio>
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extern "C" {
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extern void print_table (void);
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extern double ComputeRed (double);
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extern double ComputeGreen (double);
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extern double ComputeBlue (double);
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};
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union Color {
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struct _c {
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uint8_t g, r, b, a;
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explicit _c (const uint8_t _r, const uint8_t _g, const uint8_t _b) noexcept :
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g(_g), r(_r), b(_b), a(0u) {}
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} c;
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uint32_t number;
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explicit Color (const uint8_t r, const uint8_t g, const uint8_t b) : c(r, g, b) {}
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};
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#if 0
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static Color getColor (const int index) {
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const double fi = 2.0 * M_PI / 3.0; // úhel posunu argumentu barvy
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const double ph = M_PI / 128.0;
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double a1, a2, a3;
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uint8_t r,g,b; // proměnné barvy
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// výpočet barvy - duha
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a1 = (double) index * ph; // argument pro r
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a2 = a1 + fi; // argument pro g
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a3 = a2 + fi; // argument pro b
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r = (int)(127.0 + 127.0*sin(a1));
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g = (int)(127.0 + 127.0*sin(a2));
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b = (int)(127.0 + 127.0*sin(a3));
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Color color(r, g, b);
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return color;
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}
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#else
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static uint8_t Gauss (const double x, const double x0) {
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const double sigma = 1.0 / 2048.0, arg = x - x0;
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double r = 256.0 * exp (-sigma * arg * arg);
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return uint8_t (r);
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}
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static Color getColor (const int index) {
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uint8_t r=0,g=0,b=0; // proměnné barvy
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r = Gauss(index, 85.333);
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g = Gauss(index, 170.67);
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b = Gauss(index, 0.01) + Gauss(index, 256.0);
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Color color(r, g, b);
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return color;
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}
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#endif
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double ComputeRed (double x) {
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Color c = getColor(x);
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return double (c.c.r);
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}
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double ComputeGreen (double x) {
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Color c = getColor(x);
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return double (c.c.g);
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}
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double ComputeBlue (double x) {
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Color c = getColor(x);
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return double (c.c.b);
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}
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void print_table () {
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FILE * out = fopen("../table.c","w");
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if (!out) return;
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fprintf(out, "const unsigned table [] = {");
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for (unsigned n=0u; n<256u; n++) {
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if ((n%8) == 0u) fprintf(out, "\n");
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const Color c = getColor(n);
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fprintf(out, " 0x%06X,", c.number);
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}
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fprintf(out, "\n};\n");
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fclose(out);
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}
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