How to determine if an image has been created?

itgiawa

I've got a texture3D object:

texture3D.new()
texture3D.create(64, 64, 64, Image.FORMAT_RGB8)

I'd like to be able to grab an arbitrary image from the texture3D and see if its been created or not.

I thought I could just do this:

image = texture3D.get_layer_data(0)
if image:

but the above appears to be true for every image.

I also tried:

 image = texture3D.get_layer_data(0)
    if image.is_empty():

but it seems that none of the images are empty...

I would expect that the image.create() function would be part of the image.new() constructor and I would also expect that if an image has not been create()ed then it would be null...

xyz

I don't see any problems with described behavior. new() will create a texture object but without any actual data. create() will create Image sub-objects and allocate their data storage in specified format. If you call get_layer_data() before create() it'll always return null. Returned layer(Image) is always initialized, thus never empty, unless you manually remove its data. All as expected.

cybereality

Just fill the image with a known color when you create it (this is called a sentinel value) and then check for that pixel color to see if the image has been created. In this example, I used black, because it is easy to compare, and in most cases you will never have a pure perfect black pixel.

extends Node2D

func _ready():
	create_image(64, 64)
	
func create_image(width, height):
	var image = Image.new()
	image.create(width, height, false, Image.FORMAT_RGB8)
	image.fill(Color.black)
	
	var layer_num = 4
	var tex = Texture3D.new()
	tex.create(width, height, layer_num, Image.FORMAT_RGB8, 0)
	for i in range(layer_num):
		tex.set_layer_data(image, i)
	
	var layer = tex.get_layer_data(1)
	layer.lock()
	var value = layer.get_pixel(0, 0)
	layer.unlock()
	print("Color = " + str(value) + ", Black = " + str(Color.black))
	print("Layer Empty: ", value == Color.black)

cybereality

@xyz said: I don't see any problems with described behavior. new() will create a texture object but without any actual data. create() will create Image sub-objects and allocate their data storage in specified format. If you call get_layer_data() before create() it'll always return null. Returned layer(Image) is always initialized, thus never empty, unless you manually remove its data. All as expected.

Get layer data returns an Image object because it seems that when you create a Texture3D, the Images inside are valid, just blank. So it won't return null.

cybereality

Okay, so I did some more digging. My code above only works with filtering disabled. Once you enable filtering the layers blend into each other and you can't get a solid color. The main issue is that, you can create a Texture3D but then not add any layers, in which case calling get_layer_data will return null for any valid index. However, if you add even a single layer, then all layers in the Texture3D are initialized to valid Images. So checking for null or image empty won't work. Additionally, if filtering is enabled, now any created Images that were added to the Texture3D blend into the blank layers. So when you call get_pixel it returns some interpolated value, even for a layer that should be empty. So I don't think this will work. You'll probably just have to keep track of which layers you've created in some variable.

xyz

I must admit I don't see where the problem is. Op says "I'd like to be able to grab an arbitrary image from the texture3D and see if its been created or not".

Why would you need to do this? If I get the behavior of Texture3D correctly, images(layers) are either all created or none is created. Why do you need to test if specific image is created or not?

cybereality

Yes, I agree. It's valid behavior and it should work that way. But I can imagine cases where it may be easier to query the Image layer to check if it has data, but this would depend on what exactly you are storing in the Texture3D. In any case, it's probably a design issue. It would be easier to just initialize the Texture3D properly and assume it always has data.

itgiawa

@xyz yeah I didnt realize it created them all for me. I thought I had to check to see if each layer was created before creating it myself, which is why I asked. So no problem. Thanks for the help!