Grid position helper functions

grid_helper.glsl

// some general helpers on how to sample a 1D grid.

// returns the x/y coordinate of value inside of an 1D array/grid.
// pass in the desired index. size refers to the "width" of the grid. 
// note that you may have to round/floor the value depending on your needs, ivec2 is only available in glsl.
ivec2 get_coord(int index, int size){
    return ivec2(index % size, index / size);
}

// gets the index of a value inside of an 1D array/grid.
// pass in the desired x/y coords. size refers to the "width" of the grid. 
int get_index(int x, int y, int size){
    return x + size * y;
}

ivec4 get_neighbor_indices(int index, int size){

    // get coord of current index
    ivec2 coord = get_coord(index, size);

    // get coordinates of neighbors
    ivec2 left = ivec2(coord.x - 1, coord.y);
    int left_index = get_index(left.x, left.y, size);

    ivec2 right = ivec2(coord.x + 1, coord.y);
    int right_index = get_index(right.x, right.y, size);

    ivec2 top = ivec2(coord.x, coord.y - 1);
    int top_index = get_index(top.x, top.y, size);

    ivec2 bottom = ivec2(coord.x, coord.y + 1);
    int bottom_index = get_index(bottom.x, bottom.y, size);

    return ivec4(top_index, left_index, bottom_index, right_index);
}

An idea of how to possibly sample the neighbors of a storage buffer value. "size" refers to the "width" of the buffer, as such it's probably best to make buffers an even number to make figuring things out a bit simpler.

Have not tested fully.

Based on this
https://softwareengineering.stackexchange.com/questions/212808/treating-a-1d-data-structure-as-2d-grid