Style OpenLayers 3 cursor when drawing shapes

Question

I have a feature that allows a user to draw a square or rectangle on an OpenLayers map. I would like to change the style of the cursor. The cursor is, by default, a blue circle. I would like to change it to a square so the symbology matches the shape that the user may create.

The solution involves adding a style attribute. I need the specifics of how to implement the style attribute for a non-image cursor that is like the default blue circle but instead, a square. Thanks!

$scope.drawBoundingBox = () => {
    const bbVector = new ol.source.Vector({ wrapX: false });
    const vector = new ol.layer.Vector({
      source: bbVector
    });
    bbVector.on("addfeature", evt => {
      $scope.coords = evt.feature.getGeometry().getCoordinates();
    });
    const style = new ol.style.Style({
      stroke: new ol.style.Stroke({
        color: "#FFF",
        width: 3
      }),
      fill: new ol.style.Fill({
        color: [255, 255, 255, 0]
      })
    });
    const geometryFunction = ol.interaction.Draw.createRegularPolygon(4);
    draw = new ol.interaction.Draw({
      source: bbVector,
      type: "Circle",
      geometryFunction
    });
    vector.set("name", "boundingBox");
    vector.setStyle(style);
    map.addLayer(vector);
    map.addInteraction(draw);
  };

Answer 1

Here is a working solution that changes the default blue circle cursor to a square and allows the user to create a square or rectangle shape on the map.

  $scope.drawBoundingBox = () => {
    const bbVector = new ol.source.Vector({ wrapX: false });
    const vector = new ol.layer.Vector({
      source: bbVector
    });
    bbVector.on("addfeature", evt => {
      $scope.coords = evt.feature.getGeometry().getCoordinates();
    });

    const geometryFunction = ol.interaction.Draw.createRegularPolygon(4);

    draw = new ol.interaction.Draw({
      source: bbVector,
      type: "Circle",
      geometryFunction: geometryFunction,
      style: new ol.style.Style({
        stroke: new ol.style.Stroke({
          color: "#FFF",
          width: 3
        }),
        fill: new ol.style.Fill({
          color: [255, 255, 255, 0]
        }),
        geometryFunction,
        image: new ol.style.RegularShape({
          fill: new ol.style.Fill({
            color: '#FFF'
          }),
          stroke: new ol.style.Stroke({
            color: "blue",
            width: 3
          }),
          points: 4,
          radius: 10,
          angle: Math.PI / 4
        }),
      }),
    });
    vector.set("name", "boundingBox");
    map.addLayer(vector);
    map.addInteraction(draw);
  };