Lerping between points on an isometric map

Question

Hello, I am using an isometric TileMap that fakes 3D space by using layers as an up/down axis, and by offsetting tiles in higher layers upwards so that they appear above the layers below.

I also have an AStar3D for calculating paths between tiles on the TileMap.

I want to animate a sprite following this path, and I think this requires me to translate a given AStar3D position into a TileMap tile+layer coordinate, into the tile's local position on the map, into a global position to give the sprite to use for position lerps.

I am having trouble with TileMap's map_to_local() method because it only returns the local position of the tile's center, but I want to be able to get local positions offset from the tile center too, since sprites might not always be initiating paths from the center of a tile. map_to_local() expects a Vector2i, but I want to be able to input a Vector2.

Is there a better way of doing what I'm trying to do? Thanks!

Gina

Answer 1

In which form you keep the position of your object/sprite within the isometric world?

Borrero

Answer 2

I'm using navigation graph position as its 'real' 3D position in the map, and then using the TileMap.map_to_local to get a screenspace 2D position that accounts for the isometric skew/rotation. The 2D position is only used for setting the sprite's position on the screen, all distance/direction calculations use the 3D position.

Thanks for the response!

Gina

Answer 3

Since you have the "real" coordinates, simply multiply x and z coordinates with x and z (or y) isometric basis vectors and add the results. This should give you the screen space position.

Borrero

Answer 4

i seeee, I'll try that out, thanks!

Gina

Answer 5

I was able to get the Navigation Position to World Position working!

Though, it's been a while since Linear Algebra and I hardly understand how the transformation matrix works, haha.

I also used this as a reference for the math.

Here's my method:
(I divide my pos.z by 2 because each layer can contain tiles of either half height or full height. It was my work around for Godot's TileMap not supporting layer offsets)

func get_tile_world_transform(pos: Vector3):
	pos.x += 1
	var layer = int(pos.z)/2
	
	var matrix = Transform3D()
	var tile_length = map.tile_set.tile_size.x/2
	matrix.basis.x = tile_length * Vector3(1.0, -1.0/2.0, -1.0/2.0/sqrt(2.0))
	matrix.basis.y = tile_length * Vector3(-1.0, -1.0/2.0, -1.0/2.0/sqrt(2.0))
	matrix.basis.z = tile_length * Vector3(0.0, 1.0, -1.0/2.0/sqrt(2.0))/2
	matrix.origin = Vector3.ZERO
	
	var world_pos = matrix * pos
	world_pos.y *= -1
	
	world_pos = map.to_global(Vector2(world_pos.x, world_pos.y))
		
	return Vector3(world_pos.x,world_pos.y,map.get_layer_z_index(layer))

Though for some reason I need to offset the original Navigation Graph position by +1 in the X axis; I'm not sure why. Maybe some integer division I missed somewhere? Otherwise, it seems to be working as intended. Thanks for all the help!

But would you happen to know why I'm needing to add that pos.x offset?

Gina