Particle.h

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/*
 * Defines a particle used in flow integration.
 */
 
#ifndef PARTICLE_H
#define PARTICLE_H
 
#include "vapor/common.h"
#include <glm/glm.hpp>
#include <forward_list>
 
namespace flow {
enum FLOW_ERROR_CODE    // these enum values are available in the flow namespace.
{
    FIELD_ALL_ZERO = 4,
    MISSING_VAL = 3,
    NO_ADVECT_HAPPENED = 2,
    ADVECT_HAPPENED = 1,
    SUCCESS = 0,
    OUT_OF_FIELD = -1,
    NO_FIELD_YET = -2,
    NO_SEED_PARTICLE_YET = -3,
    FILE_ERROR = -4,
    TIME_ERROR = -5,
    GRID_ERROR = -6,
    SIZE_MISMATCH = -7,
    PARAMS_ERROR = -8
};
 
// Particle is not expected to serve as a base class.
class FLOW_API Particle final {
public:
    glm::vec3 location = {0.0f, 0.0f, 0.0f};
    float     value = 0.0f;
    double    time = 0.0;
 
    // Constructors.
    // This class complies with rule of zero.
    Particle() = default;
    Particle(const glm::vec3 &loc, double t, float val = 0.0f);
    Particle(float x, float y, float z, double t, float val = 0.0f);
 
    //
    // The "property" field allows the user to keep one or more arbitrary values that
    // are associated with this particle. It's up to the user to keep a record on
    // what these values at each index stand for.
    //
    void AttachProperty(float v);
    void ClearProperty();
    // Remove the property at a certain index.
    // If the index is out of bound, then nothing is performed
    void RemoveProperty(size_t i);
 
    auto GetPropertyList() const -> const std::forward_list<float> &;
 
    // A particle could be set to be at a special state.
    void SetSpecial(bool isSpecial);
    bool IsSpecial() const;
 
private:
    std::forward_list<float> _properties;
    // Note on the choice of using a forward_list:
    // Forward_list takes 8 bytes, whereas a vector or list take 24 bytes!
    // Fun fact: the end() iterator of a forward_list is the nullptr.
};
 
};    // namespace flow
 
#endif