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#ifndef JuliaSet_H
#define JuliaSet_H
// Codetastic 2024
#define USE_FLOATHACK // To boost float performance, comment if this doesn't work.
// inspired by
// https://en.wikipedia.org/wiki/Fast_inverse_square_root
#ifdef USE_FLOATHACK
// cast float as int32_t
int32_t intfloat(float n){ return *(int32_t *)&n; }
// cast int32_t as float
float floatint(int32_t n){ return *(float *)&n; }
// fast approx sqrt(x)
float floatsqrt(float n){ return floatint(0x1fbb4000+(intfloat(n)>>1)); }
// fast approx 1/x
float floatinv(float n){ return floatint(0x7f000000-intfloat(n)); }
// fast approx log2(x)
float floatlog2(float n){ return (float)((intfloat(n)<<1)-0x7f000000)*5.9604645e-08f; }
#else
float floatinv(float n){ return 1.f/n;}
float floatsqrt(float n){ return std::sqrt(n); }
float floatlog2(float n){ return std::log2f(n); }
#endif
////////////////////////////////////////
// Escape time mandelbrot set function,
// with arbitrary start point zx, zy
// and arbitrary seed point ax, ay
//
// For julia set
// zx = pos_x, zy = pos_y;
// ax = seed_x, ay = seed_y;
//
// For mandelbrot set
// zx = 0, zy = 0;
// ax = pos_x, ay = pos_y;
//
const float bailOut = 4; // Escape radius
const int32_t itmult = 1<<10; // Color speed
//
// https://en.wikipedia.org/wiki/Mandelbrot_set
int32_t iteratefloat(float ax, float ay, float zx, float zy, uint16_t mxIT) {
float zzl = 0;
for (int it = 0; it<mxIT; it++) {
float zzx = zx * zx;
float zzy = zy * zy;
// is the point is escaped?
if(zzx+zzy>=bailOut){
if(it>0){
// calculate smooth coloring
float zza = floatlog2(zzl);
float zzb = floatlog2(zzx+zzy);
float zzc = floatlog2(bailOut);
float zzd = (zzc-zza)*floatinv(zzb-zza);
return it*itmult+zzd*itmult;
}
};
// z -> z*z + c
zy = 2.f*zx*zy+ay;
zx = zzx-zzy+ax;
zzl = zzx+zzy;
}
return 0;
}
class PatternJuliaSet : public Drawable {
private:
float sint[256]; // precalculated sin table, for performance reasons
public:
PatternJuliaSet() {
name = (char *)"Julia Set";
}
void start() {
for(int i=0;i<256;i++){
sint[i] = sinf(i/256.f*2.f*PI);
}
}
// Palette color taken from:
// https://editor.p5js.org/Kouzerumatsukite/sketches/DwTiq9D01
// color palette originally made by piano_miles, written in p5js
// hsv2rgb(IT, cos(4096*it)/2+0.5, 1-sin(2048*it)/2-0.5)
void drawPixelPalette(int x, int y, uint32_t m){
float r = 0.f, g = 0.f, b = 0.f;
if(m){
char n = m>> 4 ;
float l =abs(sint[m>> 2&255] )*255.f ;
float s = (sint[m &255]+ 1.f)*0.5f ;
r = (max(min(sint[n &255]+0.5f,1.f),0.f)*s+(1-s))*l;
g = (max(min(sint[n+ 85&255]+0.5f,1.f),0.f)*s+(1-s))*l;
b = (max(min(sint[n+170&255]+0.5f,1.f),0.f)*s+(1-s))*l;
}
effects.setPixel(x,y,CRGB(r,g,b));
}
unsigned int drawFrame() {
uint32_t lastMicros = micros();
double t = (double)lastMicros/8000000;
double k = sin(t*3.212/2)*sin(t*3.212/2)/16+1;
float cosk = (k-cos(t))/2;
float xoff = (cos(t)*cosk+k/2-0.25);
float yoff = (sin(t)*cosk );
for(uint8_t y=0;y<VPANEL_H;y++){
for(uint8_t x=0;x<VPANEL_W;x++){
uint32_t itcount = iteratefloat(xoff,yoff,((x-64)+1)/64.f,(y)/64.f,64);
uint32_t itcolor = itcount?floatsqrt(itcount)*4+t*1024:0;
drawPixelPalette(x,y,itcolor);
}
}
blur2d(effects.leds, VPANEL_W, VPANEL_H, 64);
effects.ShowFrame();
return 0;
}
};
#endif
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