Highlight border on tile from GridMap

Question

I am making a 3D isometric game and I want the tile underneath the mouse to have a border highlight on it, like this: https://pasteboard.co/JVHYrvL.jpg

The solution needs to work no matter the location or scale of the tile as the camera can pan and zoom. I previously had a rectangle poly I moved over the tile the mouse was over but there must be a nicer way like a shader or 2D UI drawing

Answer 1

Get the position the mouse is over using ray-casting from the projected position of the camera/viewport.

Compare that position using GridMaps world_to_map(position)

Now you have a few options here

• Draw directly to the map using a mesh_library
• Use an upward facing Quadmesh MeshInstance with a Texture
• Unproject Line2D or a CanvasItem's drawn Rect2D
• Use a shader like you mentioned

If you do decide to use a SpatialMaterial with an Albedo_Texture like this which is the easiest method. Ensure to enable Transparency

Comments

I already have the code to intersect a ray, but thanks for mentioning it. I think I will go with a line2D as then I can guarantee visibility and consistent look no matter zoom levels. I will just have to unproject 4 points at each of the corners to calc size (and it's isometric)

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That part is actually easy, from the world_to_map() position draw each point diagonally based on GridMap's cell_size

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Yup, that was generally my thoughts. From my existing code I already have the centre of the tile in world coords so easy to calc corners from that