Hello, im a noob in godot and in general. Has anyone here know maybe how to implement block building system? Atm im not looking for code just in general how one should go about to make something.

If you never heard of valheim, its a 3D RPG free build exploring type game where you craft items, get resources and build houses out of blocks, like in minecraft bot you are not limited to a gridmap/tilemap.

Here is a random video from youtube

You can see when you start placing pieces into the world, the first base piece snaps to the surface of the world, then you aim next infront of the existing piece and it shows preview where you can place the next piece and it snaps together.

I have gone so far to make something thats kinda working but not like i want it to work.

When i start building (toggle) the preview block snaps to the surface, when i place the block into the world, then if my camera ray hits (mouse pointer) the collisionshape of the block and checks if the block is certain type then i get this block predefined snapping points (Node3D array) then i parse these nodes to determine where the hit result is the closest snapping point, then i return the snapping point value and do the transform of the preview block (block) to snap to the (collider block) block in the world.

block.global_transform = collider_block.global_transform * closest_node.transform *  block_snap_point.transform.affine_inverse()

There are few problems im facing atm.
1) The block snapping works only if i aim at the existing block not when i aim near that block.
2) The preview block or the next block to be placed - i cant figure out how to snap logically so that i dont have to manually select the opposite snapping point to snap to if you know what i mean
3) cant rotate snapped block while still in preview mode.

Things i have considered:
1) Using aabb to create like some sort of grid with collision shapes blocks for possible block placements and add script to check if aiming at the possible collision shape and then snap to that place. After snapping a new block to that place, remove collisionshape to save on resources. Im not sure if this could scale when you have thousands of blocks in the world.

Im sure there is a better way to go about creating this.

At the moment the snapping points are just node 3d, moved into position in editor (manually) would be nice if you could define them in code somehow, so that scaling block types would go faster.