#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);



#define stars 20
#define trajectory_length 5


float velocity[stars];
float x1[stars];       // počáteční
float x2[stars];       // koncová
float y[stars];


void setup() {
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(WHITE);
  display.display();
  Serial.begin(9600);

/*
for (int a = 0; a < stars; a++) {
  y[a] = random(0, SCREEN_HEIGHT);
}
*/


for (int a = 0; a < stars; a++) {
  x1[a] = random(0, SCREEN_WIDTH);
}

for (int a = 0; a < stars; a++) {
  x2[a] = random(0, SCREEN_WIDTH);
}

for (int a = 0; a < stars; a++) {
  velocity[a] = random(100, 200) / 100.0;
}


}

void loop() {
  display.clearDisplay();
for (int b = 0; b < stars; b++) {
  
    // display.drawPixel(x1[b], y[b], WHITE);

    display.drawLine(x1[b],y[b],x2[b],y[b]-trajectory_length,WHITE);

    y[b]=y[b]+velocity[b]; // posun v ose Y dolů - padání
    
    if ( y[b] > SCREEN_HEIGHT) {y[b] = 0;
                      x1[b] = random(0, SCREEN_WIDTH);
                      x2[b] = random(x1[b], x1[b]+trajectory_length);
                      velocity[b] = random(100, 200) / 100.0;
                      }
  
}
  display.display();
  delay(1);
}