void FluidSim::compute_phi() {
//Estimate from particles
liquid_phi.assign(3*dx);
for(unsigned int p = 0; p < particles.size(); ++p) {
Vec2f point = particles[p];
int i,j;
float fx,fy;
//determine containing cell;
get_barycentric((point[0])/dx-0.5f, i, fx, 0, ni);
get_barycentric((point[1])/dx-0.5f, j, fy, 0, nj);
//compute distance to surrounding few points, keep if it's the minimum
for(int j_off = j-2; j_off<=j+2; ++j_off) for(int i_off = i-2; i_off<=i+2; ++i_off) {
if(i_off < 0 || i_off >= ni || j_off < 0 || j_off >= nj)
continue;
Vec2f pos((i_off+0.5f)*dx, (j_off+0.5f)*dx);
float phi_temp = dist(pos, point) - 1.02f*particle_radius;
liquid_phi(i_off,j_off) = min(liquid_phi(i_off,j_off), phi_temp);
}
}
//"extrapolate" phi into solids if nearby
for(int j = 0; j < nj; ++j) {
for(int i = 0; i < ni; ++i) {
if(liquid_phi(i,j) < 0.5*dx) {
float solid_phi_val = 0.25f*(nodal_solid_phi(i,j) + nodal_solid_phi(i+1,j) + nodal_solid_phi(i,j+1) + nodal_solid_phi(i+1,j+1));
if(solid_phi_val < 0)
liquid_phi(i,j) = -0.5f*dx;
}
}
}
}
/*software rasterizer TODO could be more efficient*/
void render_triangle(Point2D v0, Point2D v1, Point2D v2,
volatile unsigned char *fb, uint16_t colour) {
int min_x = min3(v0.x, v1.x, v2.x);
int min_y = min3(v0.y, v1.y, v2.y);
int max_x = max3(v0.x, v1.x, v2.x);
int max_y = max3(v0.y, v1.y, v2.y);
Point2D p;
for (p.y = min_y; p.y <= max_y; p.y++) {
for (p.x = min_x; p.x <= max_x; p.x++) {
float w0, w1, w2;
get_barycentric(p, v0, v1, v2, &w0, &w1, &w2);
// If p is on or inside all edges, render pixel.
if (w0 >= 0 && w1 >= 0 && w2 >= 0) {
/*TODO render nicely*/
draw_pixel(p.x, p.y, fb, colour);
}
}
}
}
