How can I hide tiles until they are in the line of sight of the player?

Tomkun

Okay, I'll try that.
How can setcell() copy one cell to another tilemaplayer though?
Never mind, I found out how. There isn't a direct copy it seems but you can extract all the info you need for setcell() with different functions and use them.
However, unfortunately it seems like I am out of luck here.
I am using BetterTerrain to place my tiles and I can't seem to reproduce them faithfully as their rotation and mirroring are randomised and I can't find a way to duplicate that.

Thank you for all your help though. I have learned a lot!

xyz

Tomkun How about this instead. Make the full version of the map completely visible. Put an additional tile map layer over that. Fill this layer with full square tiles in a background color, effectively masking what's underneath. As you progress, just delete those mask cells for the cells in the map that have been revealed.

Tomkun

xyz
Yes, that would work but I have a background texture.
Basically, my dungeon is supposed to look like it was sketched on paper, so there is a background paper texture.
If I could duplicate that on the top layer and make sections transparent, that could work but I'm not sure if that's possible to do.

xyz

Tomkun Tile map layer is a canvas item. You can use it as an alpha mask.

Tomkun

xyz That sounds like the solution then. I will have a look into it. Thank you so much for all your help, pointers and suggestions!

Tomkun

xyz
Do the tiles act as the mask in this case? If I create a white tile, will that area become transparent?
Edit:
I've just answered my own question here, but no, this is not how it works. Tiles just act like tiles unfortunately.
How can I create a cell that is a mask?

xyz

Tomkun Hm, apparently the common canvas item children clipping doesn't work with tilemaps. You can render it into a separate viewport and use that viewport texture as an alpha mask. Alternatively you can slap your background texture over the tilemap by using a simple custom shader that draws the texture.

xyz

Tomkun But wait. There's a simple way still using _tile_data_runtime_update() with just the original map. Maintain a list of invisible cell coordinates. Return true from _use_tile_data_runtime_update() if received coord is in that list. In _tile_data_runtime_update() simply set tile_data.modulate.a to 0.

Tomkun

I think custom shaders are going to be a little advanced for me. I'm struggling as is. I will give the viewport idea a go.

xyz

Tomkun Example:

extends TileMapLayer

var invisibles: Array[Vector2i]

func _ready():
	for i in 5:
		invisibles.push_back(Vector2i(i,i))

func _use_tile_data_runtime_update(coords):
	return coords in invisibles
	
func _tile_data_runtime_update(coords, tile_data):
	tile_data.modulate.a = 0

With this you can even animate fading in of the tiles as they become visible.

Tomkun

xyz
Wow, that sounds perfect!
It's going to take me a while to get my head around it. I don't really get the virtual functions yet. How are they called?

xyz

Tomkun The engine calls them. You just provide the code and the return value. Same as _process() which engine calls each frame. "Virtual" here only means that the function body is optional to implement by the user.

Whenever the engine is about to draw a cell, it will call your _use_tile_data_runtime_update and if it gets true as the return value, it will call your _tile_data_runtime_update() passing it a reference to that cell's tile data. You can alter that data and that's what it will be used for drawing the cell.

It's done like this so that updating is kept efficient i.e. it's only done for cells that really need it.

Tomkun

Okay, I think I get it.
So tile_data.modulate.a = 0 will make the cell invisible and I assume tile_data.modulate.a = 1 or 255 will make it visible again?

xyz

Tomkun And tile_data.modulate.a = .5 will make it half-transparent 😉
But you don't need to ever set it to 1. You just need to keep the list of invisible cells up to date, and call notify_runtime_tile_data_update() whenever this list is changed.

Tomkun

xyz
Oh, I see, so if the tile is removed from the list, then it will become visible automatically?
No, that's not working... The tiles are being removed from the list but aren't becoming visible again.
Forget it, I was being dumb again.

Great news!
Thanks to you, it's working (kind of)! I still need to iron out some kinks in my raycasting I think, but tiles are appearing now!

xyz

Tomkun Post the code.

Tomkun

xyz
Which part?
I got the raycasting working, but I'm still not happy with the algorithm I'm using to decide which tiles to reveal.
The code that reveals the tiles is basically exactly what you wrote:

extends TileMapLayer

var invisibletiles: Array[Vector2i]
@onready var hero = $"../../Hero"

func reveal_tile(collisionpoint: Vector2):
	var coords = self.local_to_map(collisionpoint)
	var herocoords = self.local_to_map(hero.position)
	
	var x_start = min(herocoords.x, coords.x)
	var x_end = max(herocoords.x, coords.x)
	var y_start = min(herocoords.y, coords.y)
	var y_end = max(herocoords.y, coords.y)
	for x in range(x_start,x_end + 1):
		for y in range(y_start,y_end + 1):
			if Vector2i(x,y) in invisibletiles:
				invisibletiles.erase(Vector2i(x,y))
				notify_runtime_tile_data_update()
	
func _ready():
	pass

func _use_tile_data_runtime_update(coords):
	if coords in invisibletiles: return true
	else: return false
	
func _tile_data_runtime_update(coords, tile_data):
	if coords in invisibletiles:
		tile_data.modulate.a = 0

xyz

Tomkun Where do you populate the invisibletiles array? At the start it needs to contain the coords of all cells in the map, because you start with all of them being invisible.

Umm you also don't need to do that check in _tile_data_runtime_update(). That's already handled in _use_tile_data_runtime_update(). Everything that passes that check needs its alpha set to 0.

Tomkun

xyz
Oh yeah, that's a leftover from when I didn't realise I didn't have to reset the modulation back to 1.
I populate the array from the same script I use to generate the dungeon. It's very simple:

func HideCells():	
	for cell in hiddenfloorlayer.get_used_cells():
		hiddenfloorlayer.invisibletiles.push_back(cell)

xyz

Tomkun Put some prints in the reveal_tile to see if anything actually gets erased. Always put some prints when the code is not behaving as expected.

I'd suggest starting with a simpler version where only the tile the player is on gets revealed. That way you can be sure that tilemap update is actually working. Then proceed to implement a more complex algorithm for deciding which tiles to reveal.

Tomkun

xyz
I can get the tiles to reveal themselves reliably. That's not the issue any longer. What I want to improve is the algorithm I'm using to choose which tiles to reveal. At the moment it's revealing all tiles in a straight line, but I'd prefer a cone, or even a complete 360, but from what I can understand, raycasting wouldn't be an efficient way to do that.

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