Inconsistent default values in TileMap.set_cell() and TileMapPattern.set_cell()

[sbebular]

Godot version

v4.1.1.stable.official [bd6af8e]

System information

Godot v4.1.1.stable - Windows 10.0.19045 - Vulkan (Compatibility) - Radeon RX 570 Series (Advanced Micro Devices, Inc.; 31.0.21001.45002) - Intel(R) Core(TM) i3-8100 CPU @ 3.60GHz (4 Threads)

Issue description

TileMap.set_cell() and TileMapPattern.set_cell() have different default values for the alternative_tile parameter. TileMap.set_cell() defaults to 0, allowing a tile to be placed at the given coordinates if no value is provided, while TileMapPattern.set_cell() defaults to -1, which instead erases the cell at the given coordinates.
My expectation was that the behavior of these functions would be consistent, given their similarities and that the documentation for TileMapPattern.set_cell() tells users to refer to TileMap.set_cell(). I am not sure whether the default value for both functions should be 0 or -1, and ask that someone more familiar with TileSets make the decision.

Steps to reproduce

1. Create a TileMap.
2. Create a TileSetAtlasSource, add a texture to it, and create a tile.
3. Add the TileSetAtlasSource to the TileMap.
4. Create a TileMapPattern.
5. Use TileMapPattern.set_cell(), using the source_id of the TileSetAtlasSource and the atlas_coords of the created tile. Do not specify an alternative tile.
6. In the TileMap, set a cell using TileMap.set_cell(). Do not specify an alternative tile.
7. In the TileMap. set the TileMapPattern at different coordinates using TileMap.set_pattern().
8. The tile placed using TileMap.set_cell() will appear normally, while the tile(s) placed using TileMap.set_pattern() will not appear.

Minimal reproduction project

N/A

[AThousandShips]

This is a documentation issue as changing the default value isn't possible without breaking compatibility

[Mickeon]

Breaking compatibility when expectations are not being followed seems fairly reasonable. Especially when changing TileMap as a whole is something fairly desired, anyhow:

• Move TileMap layers to their own node godot-proposals#7122
• Going forward with the TileMap editor godot-proposals#6415
• Reimplement ability to flip/rotate/modulate individual tiles in a TileMap (as opposed to creating flipped/rotated/modulated tiles in the TileSet) godot-proposals#3967

The class as a whole seems to be under active development and actually quite prone to minor tweaks like these.

[jokoon]

var pattern = TileMapPattern.new()
pattern.set_size(size)
for x in range(size.x):
    for y in range(size.y):
        pattern.set_cell(Vector2i(x,y), 0, Vector2i(5,0))

I am confused, I have the same problem, but I don't see a fix.

In your example, how/where do you "get" the TileSetAtlasSource?

I just specify 0 in set_cell everywhere.

[jokoon]

My test case:

extends TileMap

func _ready():
    var grid_size = Vector2i(8,8)
    # initializing the grid cells
    for a in range(grid_size.x):
        for b in range(grid_size.y):
            #erase_cell(layer_fg,Vector2i(a,b))
            set_cell(0,Vector2i(a,b),0,Vector2i(1,0))

    #var pat = []
    var size = Vector2i(2,3)
    var pattern = TileMapPattern.new()
    pattern.set_size(size)
    for x in range(size.x):
        for y in range(size.y):
            pattern.set_cell(Vector2i(x,y), 0, Vector2i(7,0))
            #pat.append([a,b])
    #pattern_map[size] = pattern
    #pattern_map[size] = tile_set.add_pattern(pattern)
    #pattern_map[size] = tile_set.get_pattern(layer_fg, pat)
    set_pattern(0, Vector2i(1,1),pattern)
    set_cell(0, Vector2i(3,7), 0, Vector2i(4,0))
    set_cell(0, Vector2i(5,7), 0, Vector2i(5,0))
    set_cell(0, Vector2i(6,7), 0, Vector2i(6,0))
    set_cell(0, Vector2i(7,7), 0, Vector2i(7,0))

My code might have a problem, the issue seems to suggests there is a fix, but I don't see it.

[jokoon]

Ok, I understand, so to clarify, alternative_tile must be specified like so:
pattern.set_cell(Vector2i(x,y), 0, Vector2i(7,0), 0)

The documentation should have a big warning in red, recommending users to set it to 0 in gdscript.