ParallaxBackground help

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:bust_in_silhouette: Asked By Zylann
:warning: Old Version Published before Godot 3 was released.

I want to add a parallax background to my level, but I can’t find how to make it tile seamlessly and correctly. It should be simple but I never could make it work.

Here is my scene in the editor:

And this is what happens when I play the level:
game video file
game video on YouTube
It doesn’t fills all the background and it even moves the wrong way at some point :frowning:

Note: if the video file doesn’t plays in your browser please download it and play with VLC, it is not corrupted despite what my browser says.

:bust_in_silhouette: Reply From: volzhs

AFAIK, ParallaxBackground makes just one copy of layer not makes several copies to fill the whole screen.
You need to make layer large enough to cover the area as you want to show.
I don’t know how your graphic asset looks, but try to add more Sprite to ParallaxLayer and move sprites.

Also, did you noticed that sometimes, the layer has wrong movement? Look at 00:06, sometimes the backgound continues to scroll when I stop the camera, then goes back, and… it doesn’t makes any sense :'D

Edit: more precisely, this is caused by camera zoom. I tried to check “ignore camera zoom”, but the background still moves in the wrong direction when zoom occurs :s
If I disable zoom from my camera all seems fine, but my game requires zooming :frowning:

Zylann | 2016-05-30 19:16

:bust_in_silhouette: Reply From: Zylann

I didn’t found a solution yet with the ParallaxBackground node, so I crafted a simple script that works well in my case. Here it is, in case you have the same need:

# Displays a background texture which loops infinitely in all directions.
# It should be put on a Node2D under the root of your scene.
# Differences from ParallaxBackground node:
# - Just drop a texture on it, done
# - No need to have a large enough image, tiling fills all visible area
# - Works on the same layer, adjust Z as you see fit
# - Focused on camera center, so zooming won't trouble the parallax. (TODO zoom parallax?)

extends Node2D

# Background texture to repeat
export(Texture) var texture = null
# Parallax motion speed. 
# The closer to zero, the slower the background will move.
# (1,1) is in sync, above is faster.
export var parallax = Vector2(0.5, 0.5)

var _tiles_x = 0
var _tiles_y = 0

func _ready():
# If zoom changes too much in your game,
# you should call this, then update() to redraw tiles to the right range.
func update_tiles():
	var ntiles = _calculate_required_tiles()
	_tiles_x = ntiles.x
	_tiles_y = ntiles.y

func _process(delta):

func _update_position():
	var cam_pos = _get_camera_center()
	#print("cam_zoom = " + str(Vector2(1,1)/get_canvas_transform().get_scale()))
	var parallax_pos = -cam_pos * parallax
	var tsize = texture.get_size()
	var tiled_pos = parallax_pos / tsize
	var floored_parallax_pos = tsize * Vector2(floor(tiled_pos.x), floor(tiled_pos.y))
	var new_pos = cam_pos + (parallax_pos - floored_parallax_pos)


func _get_camera_center():
	var ctrans = get_canvas_transform()
	var top_left = -ctrans.get_origin()
	var vsize = get_viewport_rect().size
	var center = (top_left + 0.5*vsize) / ctrans.get_scale()
	return center

func _calculate_required_tiles():
	var tile_size = texture.get_size() * get_scale()
	var view_size = get_viewport_rect().size / get_canvas_transform().get_scale()
	var fn = view_size / tile_size
	return Vector2(ceil(fn.x), ceil(fn.y))

func _draw():
	var tsize = texture.get_size()
	var nx = _tiles_x / 2 + 1
	var ny = _tiles_y / 2 + 1
	# Draw tiles around the center
	for y in range(-ny, ny):
		for x in range(-nx, nx):
			draw_texture(texture, Vector2(x,y) * tsize)
	#draw_rect(Rect2(Vector2(0,0), Vector2(8,8)), Color(1,0,0))