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Background
The background node acts as a catch-all for input events. Any input event that isn't captured by another interactive element is processed by this node.
To add a background to your scene, add a Sprite node as the first child of the scene node, name it "background", make sure the Offset/Centered property is not checked and add the globals/background.gd script.
This enables you to use Area2D nodes for your items, which lets you draw one or more CollisionPolygon2D child nodes to capture input, using only editor tools for the drawing. You can also add Sprite nodes as children of the Area2D item node if your items are not part of the background image.
Important note: Having children on the background is possible, but discouraged. Usually there is a way of having them parallel to the background in the node tree, and not much testing has been put into children of the background. Please open an issue on GitHub if you find an insurmountable problem!
Parallax
To create an illusion of perspective in a 2D game, a technique called parallax scrolling effect can be used. This effect is achieved by adding one or more additional background layers, which are moved at a different speed than the foreground when the camera pans.
To implement a ParallaxBackground in Escoria, a Sprite with the globals/background.gd script must be used for the foreground, as described in the previous section. Since the camera limits are calculated from the size of the Sprite texture, the image used must cover the visible space of the room, with transparent regions where the parallax layers will be visible.
Each layer must have a Sprite child node with the Offset/Centered property unchecked, and the parallax image must either be larger than the foreground or be repeated using the Motion/Mirroring property of the ParallaxLayer node to counter the Motion/Scale property, which is used to control how fast the layer scrolls. Remember to adjust the Transform/Position property of the ParallaxLayer to make sure that the layer covers the left and upper edges of the viewport when the scene is played.
Note: When using camera_set_zoom or camera_set_zoom_height in combination with parallax backgrounds, the ParallaxBackground's Scroll/Ignore Camera Zoom property should be turned off so that the parallax layers do not move when zooming.