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jtoumey / connectivity

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Generate associations between cells and edges (and vice-versa) #4

Closed jtoumey closed 5 years ago

jtoumey commented 5 years ago

Either during the edge generation step or after, map the edges composing each cell to the cell itself.

Likewise, extend the edge item s.t. it may know the cell indices of its two neighbors.

jtoumey commented 5 years ago

This may not be possible during edge generation. Currently, each edge for a cell is created and then tested for uniqueness. If it is already on the edge list, the edge is discarded. There is no way to look back through the edge list and identify the ID of the already-added edge.

Creating this mapping after the edge generation may be possible by searching for appropriate vertices.

jtoumey commented 5 years ago

For generating association after edge_list generation:

for each cell in cell_list:
    for each edge // based on four cardinal directions
        start_vertex = ...
        end_vertex = ...
        for each edge in edge_list:
            slow search for matching first and then second vertex
jtoumey commented 5 years ago

For generating association during edge_list generation, findUniqueFaceNeighbors could, if the edge is determined not unique, return the cell which already possesses the edge in the UniqueCellStatus struct. From there, the code could retrieve this edge ID from the previous cell and then store it in the current cell.

jtoumey commented 5 years ago

I implemented the first method. It uses a slow lookup of every edge until the start and end vertices match (or vice versa). This brings up the issues of 1) Standardizing edge vertex ordering and 2) Developing a faster method for finding the appropriate edge. I think I could store the edges in a kd-tree with the start and end vertices as the dimensions and the edge ID as the salient piece of data. This modification is extra though.

jtoumey commented 5 years ago

Also, I need to store adjacent cells for each edge. This is more pertinent information for a fluid mesh.

jtoumey commented 5 years ago

Did so in a very messy brute force fashion. I think the best way would be to work it into the findUniqueFaceNeighbors routine but then that function is doing too much. Also, it would be wise to make edge_list its own class.

jtoumey commented 5 years ago

Closing for now. Further improvements discussed above represent a significant investment of work for minimal speed-up.