/**
* Set the layer that a given shape will be displayed in. Since the shapes in this game are two
* dimensional, it must be decided which will appear "on top" when two shapes overlap. The shape
* in the higher layer will appear on top.
*
* <p>Setting a shape's layer will only affect how it is displayed; a shape's layer has no effect
* on how it interacts with other shapes. (For example, two shapes can touch even if they are in
* different layers. See {@link Shape#isTouching(Shape)}.)
*
* @param shape the shape whose layer is being set.
* @param layer the layer into which this shape will be moved.
*/
static void setLayer(Shape shape, int layer) {
removeFromLayers(shape);
// add new stuff
if (!layerContents.containsKey(layer)) {
layerContents.put(layer, new CopyOnWriteArrayList<Shape>());
int insertionPoint = ~Collections.binarySearch(layers, layer);
layers.add(insertionPoint, layer);
}
layerContents.get(layer).add(shape);
layerOf.put(shape, layer);
}
