Create Julia_Set_Demo.ino

examples/Julia_Set_Demo/Julia_Set_Demo.ino

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+#define PANEL_RES_X 128    // Number of pixels wide of each INDIVIDUAL panel module. 
+#define PANEL_RES_Y 64     // Number of pixels tall of each INDIVIDUAL panel module.
+#define PANEL_CHAIN 1      // Total number of panels chained one to another
+#define USE_FLOATHACK      // To boost float performance, comment if this doesn't work. 
+
+#include <ESP32-HUB75-MatrixPanel-I2S-DMA.h>
+
+MatrixPanel_I2S_DMA *dma_display = nullptr;
+
+// 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;
+}
+
+float sint[256]; // precalculated sin table, for performance reasons
+
+// 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;
+  }
+  dma_display->drawPixelRGB888(x,y,r,g,b);
+}
+
+void drawCanvas() {
+  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<PANEL_RES_Y;y++){
+    for(uint8_t x=0;x<PANEL_RES_X;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);
+    }
+  }
+}
+
+volatile int frameCounts=0;
+void Task1code(void *parameter){
+  while(true){
+    drawCanvas();
+    delay(1);
+    frameCounts++;
+  }
+}
+
+void setup() {
+  HUB75_I2S_CFG::i2s_pins _pins={
+//  R1, G1, B1, R2, G2, B2,  A,  B,  C,  D,  E,LAT, OE,CLK, 
+    25, 26, 27, 14, 12, 13, 23, 19,  5, 17, 18,  4, 15, 16,
+  };
+  HUB75_I2S_CFG mxconfig(
+    PANEL_RES_X, // Module width
+    PANEL_RES_Y, // Module height
+    PANEL_CHAIN, // chain length
+    _pins
+  );
+
+  // Display Setup
+  dma_display = new MatrixPanel_I2S_DMA(mxconfig);
+  dma_display->begin();
+  dma_display->clearScreen();
+  dma_display->setBrightness(64);
+  setCpuFrequencyMhz(240);
+
+  for(int i=0;i<256;i++){
+    sint[i] = sinf(i/256.f*2.f*PI);
+  }
+
+  xTaskCreatePinnedToCore(\
+      Task1code, /* Function to implement the task */\
+      "Task1", /* Name of the task */\
+      10000,  /* Stack size in words */\
+      NULL,  /* Task input parameter */\
+      4,  /* Priority of the task */\
+      NULL,  /* Task handle. */\
+      0); /* Core where the task should run */
+
+  Serial.begin(115200);
+}
+
+uint64_t lastMillis=0;
+void loop() {
+  if(millis()-lastMillis>=1000){
+    // log frame rate to serial
+    Serial.print("fps: ");
+    Serial.println(frameCounts);
+    lastMillis += 1000;
+    frameCounts=0;
+  }
+}