/*
* Copyright (C) 2020 Christopher J. Howard
*
* This file is part of Antkeeper source code.
*
* Antkeeper source code is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Antkeeper source code is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Antkeeper source code. If not, see .
*/
#include "pheromone-matrix.hpp"
#include "math/math.hpp"
void convolve(pheromone_matrix* matrix, const float* kernel, int kernel_size)
{
float* front = matrix->buffers[matrix->current];
float* back = matrix->buffers[(matrix->current + 1) % 2];
const int kernel_radius = kernel_size << 1;
// For each pheromone matrix row
for (int i = 0; i < matrix->rows; ++i)
{
// For each pheromone in the row
for (int j = 0; j < matrix->columns; ++j)
{
// Reset accumulator
float accumulator = 0.0f;
// For each kernel row
for (int k = -kernel_radius; k <= kernel_radius; ++k)
{
// For each kernel element
for (int l = -kernel_radius; l <= kernel_radius; ++l)
{
// Determine row and column of pheromone corresponding to the kernel element.
int m = i + k;
int n = j + l;
// If the row and column indices are within the matrix
if (m >= 0 && m < matrix->rows && n >= 0 && n < matrix->columns)
{
// Multiply pheromone strength in the front buffer by the kernel value and add it to the accumulator.
accumulator += front[m * matrix->columns + n] * kernel[(k + kernel_radius) * kernel_size + l + kernel_radius];
}
}
}
// Set pheromone strength in the back buffer equal to the accumulator value
back[i * matrix->columns + j] = accumulator;
}
}
// Swap buffers
matrix->current = (matrix->current + 1) % 2;
}
void evaporate(pheromone_matrix* matrix, float factor)
{
const int size = matrix->columns * matrix->rows;
for (int i = 0; i < size; ++i)
{
matrix->buffers[matrix->current][i] *= factor;
}
}
void diffuse(pheromone_matrix* matrix)
{
const math::matrix diffusion_kernel =
math::mul(
math::matrix
{{
{1, 2, 1},
{2, 4, 2},
{1, 2, 1}
}},
1.0f / 16.0f);
convolve(matrix, &diffusion_kernel[0][0], 3);
}