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Constants

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Determines how much distance gets added when traversing each type of terrain: field, road, and forest.

float[] TERRAIN_WEIGHTS = {1, 0.3, 3};

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When distances are normalized (scaled to a [0, 1] range), we need to define what should be considered the maximum distance.

int MAX_DISTANCE = 20;

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MapCellModel

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MapCellModel manages state for one map cell.

class MapCellModel {

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Instance variables

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A few integers keeping track of this cell's map coordinates and terrain type.

  int i, j, terrain;

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The cell's distance to the nearest hospital. This is updated frequently by MapModel.update_cell_distances

  float distance;

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Keep track of whether this cell has a town and whether this cell has a hospital.

  boolean has_town, has_hospital;

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Constructor

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The constructor is straightforward; we just store the values passed in and set default values for has_town and has_hospital.

  MapCellModel(int _i, int _j, int _terrain) {
    i = _i; 
    j = _j; 
    terrain = _terrain;
    has_town = false;
    has_hospital = false;
  }

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add_town

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Adds a town

  void add_town() {
    has_town = true;
  }

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add_hospital

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Adds a hospital

  void add_hospital() {
    has_hospital = true;
  }

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remove_hospital

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Removes a hospital

  void remove_hospital() {
    has_hospital = true;
  }

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is_free

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Return true when there is no town or hospital here.

  boolean is_free() {
    return !(has_town || has_hospital);
  }

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terrain_difficulty

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Looks up and returns the terrain difficulty. This method and those preceding it might seem pointless when their work is accomplished in one simple line of code. However, it's important that each part of your program minds its own business, and these methods help achieve that. This becomes especially important when you want to change your program; The more different parts of your code reach into each others' internals, the more likely it is that a change will result in an error somewhere else.

  float terrain_difficulty() {
    return TERRAIN_WEIGHTS[terrain];
  }

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normalized_distance

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Scale distance to a range between 0 and 1. This function relies on some convenient built-in Processing functions.

  float normalized_distance() {
   return max(0, min(MAX_DISTANCE, map(distance, 0, MAX_DISTANCE, 0, 1)));
  }

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equals

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Defines how MapCellModels should be compared with each other for equality. Here, two MapCellModels are equal if they share i and j. This is used internally by ArrayList when figuring out whether a particular MapCellModel is in an ArrayList.

  boolean equals(MapCellModel other) {
   return i == other.i && j == other.j; 
  }
  
}

MapCellModel.pde