Particles create particle trails of varyin colors on an LED strip.

` #include "particles.h"

ParticleEmitter emitter = ParticleEmitter(PIXEL_COUNT);

void particles() {
  emitter.stripPosition = random(100) / 100.0;

  for (int j=0; j < emitter.numParticles * 10; j++) {  
    
    for (int i=0; i < emitter.numParticles; i++) {
      
      particle prt = emitter.updateParticle(i);
      uint16_t pixel = leds.numPixels() * prt.currentStripPosition;
  
      // High velocity particles have longer tails
      uint8_t tailLength = abs(prt.velocity * 5);
      uint8_t slot = pixel;
      
      for (int z=0; z < tailLength; z++) { 
        
        float colorScale = ( (tailLength-z*0.999) / tailLength );
        if (z == 0 && prt.dimmed) {
          colorScale *= 0.25;
        }

        strip.setPixelColor(slot, strip.Color(prt.redColor*colorScale, 
                                              prt.blueColor*colorScale, 
                                              prt.greenColor*colorScale));

        slot = pixel + ((z+1) * (prt.velocity > 0 ? -1 : 1));
      }
      strip.setPixelCoor(slot, strip.Color(0,0,0));
    }
    leds.show();
    delay(50);
  }
}