sph.h

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#include "include.h"

#ifndef SPH_H
#define SPH_H

#define kMass   0.010543f //kg uniform particle mass
#define kRadius     0.005f //m -- physical particle radius (for collision detection against mainly)
#define kH (0.03f) //m 6 * kRadius -- radius particles will interact with neighbors
#define kH2     (0.0009f) //m^2 (kH * kH) -- radius of interaction squared
#define kStiffness 0.08f
#define kRestDensity    82.0f //kg.m^3
#define kLinearViscocity 0.02f



#define kGravity 9.8f
#define kWallStiff 10000
#define kWallDamp   256
#define kDeltaTime  0.004f
#define kMaxAccel   200 //m.s^2
#define kScale  0.04f
#define kEpsilon 0.000001f

/*
W(r-rb,h) = 315 / 64pi h^9(h^2 - |r-rb|^2)^3
gradW(r-rb,h) = -45 / pi h^6 (h - |r-rb|)^2 [r-rb]/[r-rb]
lapW(r-rb,h)= 45 / pi h^6 [ h - |r-rb|)
*/

#define POLY6_KERN      (315.0f / (64.0f * MY_PI * (float)pow(kH, 9)))
#define GRAD_POLY6_KERN 945.0f / (32.0f * MY_PI * (float)pow(kH, 9));
#define LAP_POLY6_KERN  945.0f / (32.0f * MY_PI * (float)pow(kH, 9));
#define SPIKY_KERN      (-45.0f / (MY_PI * (float)pow(kH, 6)))
#define VISCOSITY_KERN  (45.0f / (MY_PI * (float)pow(kH, 6)))

#define MAX_NEIGHBOR 64

typedef struct
{
    vec3 pos;
    vec3 vel;
    vec3 acc;
    float pressure;
    float density;
    //  float near_pressure;
    //  float near_density;
    float mass;
    int nbCount;
    int nbList[MAX_NEIGHBOR];
} particle_t;

#define GRID_SIZE 6

#define MAX_GRID_PARTICLE 4000
typedef struct
{
    particle_t part[MAX_GRID_PARTICLE];
    int num_part;
} voxel_t;



class Sph
{
public:
    Sph();
    void init(int num_particle);
    void step(int frame);
    void render();

private:
    void calc_density_pressure(int i);
    void calc_force(int i);
    void calc_pos(int i);
    void update_grid();
    void update_neighbors();
    float norm2(vec3 &x, vec3 &y);


    particle_t *part;
    bool initialized;
    unsigned int last_rendered;
    unsigned int last_calculated;
    int num_particle;


    // define fluid bounds
    vec3 max_bound;
    vec3 min_bound;
    int grid_width;
    int grid_height;
    int grid_depth;
    voxel_t grid[GRID_SIZE][GRID_SIZE][GRID_SIZE];



    // constant kernel factors
    float poly6_kern;
    float grad_poly6_kern;
    float lap_poly6_kern;
    float spiky_kern;
    float viscosity_kern;
};

#endif