source: sipes/modules_contrib/openlayers/docs/RAW_LAYERS.txt @ 1e95969

Raw layers are an addition to OpenLayers post-alpha7 which allow users to 
manually add points to a layer type. In comparison to the layer_type 
method of pulling in custom data, this allows you to 'push' data into the 
layer data array itself. In any case where reusability is a priority, 
layer_types should be utilized (as documented in LAYER_TYPES.txt). However, 
this is a quick method for success that may be more accessible to more 
developers.

A brief, example-only implementation of an arbitrary layer is below.

/**
 * Implementation of hook_ctools_plugin_api().
 * Required to provide layers
 */
function geolocator_ctools_plugin_api($module, $api) {
  if ($module == "openlayers") {
    switch ($api) {
      case 'openlayers_layers':
        return array('version' => 1);
    }
  }
}

/**
 * One can have the 'features' => element point to a function 
 * or be built on the fly within the _layers method. However, 
 * close attention must be paid to ctools caching in order to 
 * insure that dynamic data stays dynamic
 */
function geolocator_openlayers_layers() {
  $layers = array();
  $layer = new stdClass();
  $layer->api_version = 1;
  $layer->name = 'afghanistan';
  $layer->title = 'One Point on Afghanistan';
  $layer->description = '';
  $layer->data = array(
    'layer_type' => 'openlayers_layer_type_raw',
    'projection' => array('900913'),
    'features' => array(
      array(
      "wkt"=> "POINT(65 33)",
      "projection"=> "4326",
      "attributes"=> 
        array(
          "name"=> "Afghanistan",
          "description"=> "248"
        )
      )
    )
  );
  $layers[$layer->name] = $layer;
  return $layers;
}

/**
 * map_preprocess_alter allows one to add a new layer to a map
 * before layers are rendered and data is pulled from them.
 */
function geolocator_openlayers_map_preprocess_alter(&$map) {
  $map['layers']['afghanistan'] = 'afghanistan';
  $map['layer_activated']['afghanistan'] = 'afghanistan';
  $map['layer_switcher']['afghanistan'] = 'afghanistan';
}