geometry.c

/*
The MIT License (MIT)

Copyright (c) 2014 Adam Simpson

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/

#include <stdio.h>
#include "geometry.h"
#include "fluid.h"

void constructFluidVolume(fluid_particle **fluid_particle_pointers, fluid_particle *fluid_particles, AABB_t *fluid, int start_x, 
			  int number_particles_x, edge_t *edges, float spacing, param *params)
{
    int num_y;
    
    // Number of particles in y,z, number in x is passed in
    num_y = floor((fluid->max_y - fluid->min_y ) / spacing);
    
    // zero out number of edge particles
    edges->number_edge_particles_left = 0;
    edges->number_edge_particles_right = 0;
    
    // Place particles inside bounding volume
    float x,y;
    int nx,ny;
    int i = 0;
    fluid_particle *p;
    for(ny=0; ny<num_y; ny++) {
        y = fluid->min_y + ny*spacing;
        for(nx=0; nx<number_particles_x; nx++) {
            x = fluid->min_x + (start_x + nx)*spacing;
            p = fluid_particles + i;
            p->x = x;
            p->y = y;
            
            // Set pointer array
            fluid_particle_pointers[i] = p;
	    fluid_particle_pointers[i]->id = i;
            i++;
        }
    }

    int rank;
    MPI_Comm_rank(MPI_COMM_COMPUTE, &rank);
    printf("rank %d max fluid x: %f\n", rank,fluid->min_x + (start_x + nx-1)*spacing);

    params->number_fluid_particles_local = i;
    params->max_fluid_particle_index = i - 1;
}

// Sets upper bound on number of particles, used for memory allocation
// These numbers are set judiciously for TitanTitan as the number of particles is always small
void setParticleNumbers(AABB_t *boundary_global, AABB_t *fluid_global, edge_t *edges, oob_t *out_of_bounds, int number_particles_x, float spacing, param *params)
{
    int num_x, num_y, max_y;
    

    // Set fluid local
    num_x = number_particles_x;
    num_y = floor((fluid_global->max_y - fluid_global->min_y ) / spacing);
    max_y = floor((boundary_global->max_y - boundary_global->min_y ) / spacing);

    // Maximum edge(halo) particles
    edges->max_edge_particles = params->number_fluid_particles_global;

    // The out of bounds particles can become quite large
    // If a flood of particles flows into and then out of a node
    // This will be large
    out_of_bounds->max_oob_particles = params->number_fluid_particles_global;

    // Initial fluid particles
    int num_initial = num_x * num_y;
    printf("initial number of particles %d\n", num_initial);

    // Allow space for all particles if neccessary
    int num_local_max = params->number_fluid_particles_global;

    out_of_bounds->number_vacancies = 0;
    
}

// Set local boundary and fluid particle
void partitionProblem(AABB_t *boundary_global, AABB_t *fluid_global, int *x_start, int *length_x, float spacing, param *params)
{
    int i;
    int rank;
    MPI_Comm_rank(MPI_COMM_COMPUTE, &rank);
    int nprocs;
    MPI_Comm_size(MPI_COMM_COMPUTE, &nprocs);

    // number of fluid particles in x direction
    // +1 added for zeroth particle
    int fluid_particles_x = floor((fluid_global->max_x - fluid_global->min_x ) / spacing) + 1;
    
    // number of particles x direction
    int *particle_length_x = malloc(nprocs*sizeof(int));
    
    // Number of particles in x direction assuming equal spacing
    int equal_spacing = floor(fluid_particles_x/nprocs);
    
    // Initialize each node to have equal width
    for (i=0; i<nprocs; i++)
        particle_length_x[i] = equal_spacing;
    
    // Remaining particles from equal division
    int remaining = fluid_particles_x - (equal_spacing * nprocs);
    
    // Add any remaining particles sequantially to left most nodes
    for (i=0; i<nprocs; i++)
        particle_length_x[i] += (i<remaining?1:0);
    
    // Number of particles to left of current node
    int number_to_left = 0;
    for (i=0; i<rank; i++)
        number_to_left+=particle_length_x[i];
       
    // starting position of nodes x particles
    *x_start = number_to_left;
    // Number of particles in x direction for node
    *length_x = particle_length_x[rank];
        
    // Set node partition values
    params->tunable_params.node_start_x = fluid_global->min_x + ((number_to_left-1) * spacing);
    params->tunable_params.node_end_x   = params->tunable_params.node_start_x + (particle_length_x[rank] * spacing);
    
    if (rank == 0)
        params->tunable_params.node_start_x  = boundary_global->min_x;
    if (rank == nprocs-1)
        params->tunable_params.node_end_x   = boundary_global->max_x;

    printf("Rank %d start_x: %f, end_x :%f\n", rank, params->tunable_params.node_start_x, params->tunable_params.node_end_x);

    // Update requested number of particles with actual value used
    int num_y = floor((fluid_global->max_y - fluid_global->min_y ) / spacing);
    int total_x = 0;
    for(i=0; i<nprocs; i++)
        total_x += particle_length_x[i];
    params->number_fluid_particles_global = total_x * num_y;

    free(particle_length_x);

}

////////////////////////////////////////////////
// Utility Functions
////////////////////////////////////////////////
float min(float a, float b){
    float min = a;
    min = b < min ? b : min;
    return min;
}

float max(float a, float b){
    float max = a;
    max = b > max ? b : max;
    return max;
}

int sgn(float x) {
    int val = 0;
    if (x < 0.0)
        val = -1;
    else if (x > 0.0)
        val = 1;

    return val;
}