How to optimize getting pixel color using raycasting for Compatible renderer

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1

Godot Version

4.4.1

Question

Hi everyone,
I followed a tutorial and make a function to get color of a pixel using ray-casting method. The result came very quick in Forward+ renderer, but in Compatible, it runs very slow , around 3~4 seconds.

My plan is making a webgame , the map is a big bmp file, and this is not very good. Is there any solution?

func _on_player_province_selected(coord) -> void:
	var province_color = province_map.get_image().get_pixel(coord.x*10, coord.y*10)
	var selected_prov = $Provinces.color2province[province_color]
	print(selected_prov)
	pass

func shoot_ray():
	var mouse_pos = get_viewport().get_mouse_position()
	var ray_len = 2000
	var from = camera.project_ray_origin(mouse_pos)
	var to = from + camera.project_ray_normal(mouse_pos)*ray_len
	var space = get_world_3d().direct_space_state
	var ray_query = PhysicsRayQueryParameters3D.new()
	ray_query.from = from
	ray_query.to = to
	var raycast_res = space.intersect_ray(ray_query)
	
	if !(raycast_res.is_empty()):
		var rx = raycast_res.position.x
		#var ry = raycast_res.position.y
		var rz = raycast_res.position.z
		print("FOUND")
		province_selected.emit(Vector2(rx,rz))

(these two functions are separated in each files)

2

How often are you making this raycast? Though I don’t think it should have a noticeable impact on performance even if you are making it every frame. Maybe it is because of the get_pixel call?

3

I called the raycast every time i clicked on the screen

func _unhandled_input(event: InputEvent) -> void:
	if event is InputEventMouseButton and event.button_index == MOUSE_BUTTON_LEFT and event.is_pressed():
		shoot_ray()

about get_pixel, yeah i tested it out and it is the problem

4

Would it be faster if you fetched the image data at the start and just accessed it that way instead of using get_pixel?

5

I don’t understand what you mean. Can you tell me more about it?

6

If you use get_data() you can a PackedByteArray of the map data. Checking that may be faster than calling get_pixel().

7

So if I am not wrong, I’m going to extract colors from PackedByteArray? If so, how can I do that? I checked out the docs and there are no color properties kek

8

PackedByteArray is a list of the colors. It’s just they are in byte form instead of Color form.

9

I made a array :

@onready var packed_data
# Called when the node enters the scene tree for the first time.
func _ready() -> void:
	packed_data = PackedByteArray(province_map.get_image().get_data())
	print(packed_data)
	pass

and got a PackedByteArray like this:
[0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 0, 29, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38, 19, 34, 38,[...]

But how can I access the byte to get the color? These are my attempts but nothing worked

var province_color = Color(packed_data[coord.x*10][coord.y*10])

and

var n = (coord.y *10 * province_map.get_width()) + coord.x *10
var province_color = Color(packed_data[n][n+1][n+2])

But I always got an error
image

I dont know how to correctly get the color

10

Me neither, but moving get_image() to @onready allready gives a nice boost, without fiddling with bytes:

extends TextureRect
@onready var map_img = texture.get_image()
@onready var mat = get_material()

func _on_gui_input(event):
	if event is InputEventMouseButton and event.button_index == MOUSE_BUTTON_LEFT and event.is_pressed():
		var mouse_pos = get_local_mouse_position()
		var color = map_img.get_pixel(mouse_pos.x, mouse_pos.y)
		mat.set_shader_parameter("highlight_color", color);

This is a test I made with a TextureRect. I am also sending the pixel color to a custom shader for highlighting the map region.

1 Like
11

Yeah maybe tassup’s solution works better, I guess getting the image is what takes longer than the bytes.

But if you want to know how to access the color, I think it’s something like this: the pixels are all listed in left to right, top to bottom order. Each number (byte) is a component of the color, and it goes in RGBA order. So you need to check four bytes at once to get the color.

2 Likes
12

I came up using tassup’s method, and it does very well! I thought it was get_pixel problem, but that is on get_image instead.

thanks you two for helping me!

Here are the way i boosted the process, in case someone needs:

Change from this:
var province_color = province_map.get_image().get_pixel(coord.x*10, coord.y*10) to

@onready var province_image = province_map.get_image()
var province_color = province_image.get_pixel(coord.x*10, coord.y*10)
2 Likes