particle_system.hpp

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#ifndef PARTICLE_SYSTEM_H
#define PARTICLE_SYSTEM_H
 
#include <cstdint>
#include <functional>
#include <set>
 
#include "src/system/ext/random8.h"
 
#include "src/modes/include/hardware/lamp_type.hpp"
 
#include "particle.hpp"
 
namespace lampda::modes {
 
using LampTy = hardware::LampTy;
 
class ParticleSystem
{
public:
  ParticleSystem() : particuleCount(0) { reset(); }
 
  void reset()
  {
    occupiedSpacesSet.clear();
    for (size_t i = 0; i < ParticleSystem::maxParticuleCount; ++i)
    {
      isAllocated[i] = false;
    }
  }
 
  void set_max_particle_count(const uint16_t _particleCount)
  {
    particuleCount = std::min<uint16_t>(ParticleSystem::maxParticuleCount, _particleCount);
    reset();
  }
 
  void init_particules(const std::function<int16_t(size_t)>& positionGeneratorFunction)
  {
    occupiedSpacesSet.clear();
    for (size_t i = 0; i < particuleCount; ++i)
    {
      isAllocated[i] = false;
      spawn_particule(i, positionGeneratorFunction);
    }
  }
 
  void init_deferred_particules(uint8_t maxParticlesToPop,
                                const std::function<int16_t(size_t)>& positionGeneratorFunction)
  {
    for (size_t i = 0; i < particuleCount and maxParticlesToPop > 0; ++i)
    {
      if (isAllocated[i])
      {
        // already allocated, do not reuse
        continue;
      }
      spawn_particule(i, positionGeneratorFunction);
      maxParticlesToPop--;
    }
  }
 
  void iterate_no_collisions(const utils::vec3d& accelerationCartesian,
                             const float deltaTime_s,
                             const bool shouldContrain = true)
  {
    for (size_t i = 0; i < particuleCount; ++i)
    {
      // do not iterate non allocated particles
      if (not isAllocated[i])
        continue;
 
      Particle& p = particules[i];
      // apply force and constrain
      p.apply_acceleration(accelerationCartesian, deltaTime_s, shouldContrain);
    }
  }
 
  void iterate_with_collisions(const utils::vec3d& accelerationCartesian,
                               const float deltaTime_s,
                               const bool shouldContrain = true)
  {
    for (size_t i = 0; i < particuleCount; ++i)
    {
      // do not iterate non allocated particles
      if (not isAllocated[i])
        continue;
 
      Particle& p = particules[i];
      const int16_t ledIndex = p._savedLampIndex;
 
      // simulate instead of updating directly
      const Particle& newP = p.simulate_after_acceleration(accelerationCartesian, deltaTime_s, shouldContrain);
 
      // update particle position in occupation set
      const int16_t newLedIndex = newP._savedLampIndex;
      if (newLedIndex != ledIndex)
      {
        // check collision : no collision
        if (not is_position_taken(newLedIndex))
        {
          occupiedSpacesSet.erase(ledIndex);
          occupiedSpacesSet.insert(newLedIndex);
        }
        // check collision : collision !!
        else
        {
          // refuse movement, rebound speed
          p.thetaSpeed_radS = -p.thetaSpeed_radS * 0.75;
          p.zSpeed_mS = -p.zSpeed_mS * 0.75;
          continue;
        }
      }
 
      // update particle
      p = newP;
    }
  }
 
  uint16_t depop_particules(const std::function<bool(const Particle&)>& shouldDepopFunction)
  {
    uint16_t particleCount = 0;
    for (size_t i = 0; i < particuleCount; ++i)
    {
      // do not depop non allocated particles
      if (not isAllocated[i])
        continue;
 
      auto& parti = particules[i];
      if (shouldDepopFunction(parti))
      {
        isAllocated[i] = false;
        occupiedSpacesSet.erase(parti._savedLampIndex);
      }
      else
      {
        particleCount += 1;
      }
    }
    return particleCount;
  }
 
  uint16_t show(const std::function<uint32_t(int16_t, const Particle&)> sample_color, LampTy& lamp)
  {
    uint16_t particleCount = 0;
    for (size_t i = 0; i < particuleCount; ++i)
    {
      // do not show non allocated particles
      if (not isAllocated[i])
        continue;
      const auto& particle = particules[i];
      const auto& index = particle._savedLampIndex;
      if (modes::is_led_index_valid(index))
        lamp.setPixelColor(index, sample_color(i, particle));
      else
        particleCount += 1;
    }
    return particleCount;
  }
 
  uint16_t get_number_of_active() const
  {
    uint16_t particleCount = 0;
    for (size_t i = 0; i < particuleCount; ++i)
    {
      // do not show non allocated particles
      if (not isAllocated[i])
        continue;
      particleCount += 1;
    }
    return particleCount;
  }
 
protected:
  bool is_position_taken(const int16_t pos) const { return occupiedSpacesSet.find(pos) != occupiedSpacesSet.cend(); }
 
  void spawn_particule(const size_t index, const std::function<int16_t(size_t)>& positionGeneratorFunction)
  {
    int16_t pos = positionGeneratorFunction(index);
    int maxTries = 3;
    while (ParticleSystem::is_position_taken(pos) and maxTries > 0)
    {
      pos = positionGeneratorFunction(index);
      maxTries--;
    }
    // generate start position from user function
    const auto& helixCoordinates = modes::strip_to_helix_unconstraint(pos);
    particules[index] = Particle(utils::vec3d {helixCoordinates.x, helixCoordinates.y, helixCoordinates.z});
    occupiedSpacesSet.insert(pos);
    isAllocated[index] = true;
  }
 
private:
  static constexpr uint16_t maxParticuleCount = 512; 
  Particle particules[maxParticuleCount];            
  bool isAllocated[maxParticuleCount];               
 
  std::set<int16_t> occupiedSpacesSet; 
 
  uint16_t particuleCount;
};
 
} // namespace lampda::modes
 
#endif