Select a block of tiles from tilemap by click and dragging

Question

I'm creating my first game in Godot 3.1, a top-down 2D sim game where you can build rooms on a space station. I am using a tileset I created inside a TileMap node. I placed a script inside the node that checks for the mouse position in the world, converts it into a tilemap coordinate, then loads a tile into that tilemap coordinate.

func _input(event):
if (event is InputEventMouse):
    var button = event.get_button_mask()
    if (button == 1):
        var tile_pos = world_to_map(event.position)
        var name = _tileset.tile_get_name(0)
        set_cellv(tile_pos, _tileset.find_tile_by_name(name))

Works like a champ! As long as the left mouse button is held down, any tile the mouse pointer touches is filled with the tile from the tileset.

Now I am trying to expand this function so that I can click the world and drag across several tiles to form a rectangle or square, then have all of the tiles inside the selected area filled with the selected tile.

func _input(event):
if (event is InputEventMouse):
    var button = event.get_button_mask()
    if (button == 1):
        var tile_pos = world_to_map(event.position)
        if (dragStart == Vector2(-1,-1)):
            dragStart = tile_pos
        var name = _tileset.tile_get_name(0)
        if (dragStart != Vector2(-1,-1) && dragStart != tile_pos):
            var newX = dragStart.x - tile_pos.x
            var newY = dragStart.y - tile_pos.y
            while (newX != 0 && newY != 0):
                var next = Vector2(-1,-1)
                if newX > 0:
                    next = Vector2(dragStart.x - 1,dragStart.y)
                    newX = newX - 1
                elif newX < 0:
                    next = Vector2(dragStart.x + 1,dragStart.y)
                    newX = newX + 1
                elif newX == 0:
                    if newY > 0:
                        next = Vector2(dragStart.x,dragStart.y - 1)
                        newY = newY - 1
                    elif newY < 0:
                        next = Vector2(dragStart.x,dragStart.y + 1)
                        newY = newY + 1
                print(next)
                set_cellv(next, _tileset.find_tile_by_name(name))
    else:
        dragStart = Vector2(-1,-1)

However, it seems to only load some of the tiles and functions sporadically. Am I not understanding how the system iterates through the while loop or am I missing something else?

Answer 1

Sometimes, you just need a break to see what you were missing. I had the code all wrong. After the lightbulb went off, here's what I came up with:

func _input(event):
if (event is InputEventMouse && buildOn == true):
    var button = event.get_button_mask()
    if (button == 1):
        var name = _tileset.tile_get_name(14)
        var oldRect = get_used_cells_by_id(14)
        var i = 0
        while (i < oldRect.size()):
            set_cellv(oldRect[i],-1)
            i = i + 1
        var tile_pos = world_to_map(event.position)
        if (dragStart == Vector2(-1,-1)):
            dragStart = tile_pos
        if (dragStart != Vector2(-1,-1)):
            var newX = dragStart.x - tile_pos.x
            var next = Vector2(-1,-1)
            var startX = dragStart.x
            while (newX != 0):
                var newY = dragStart.y - tile_pos.y
                var startY = dragStart.y
                if newX > 0:
                    while (newY != 0):
                        if newY > 0:
                            next = Vector2(startX,startY)
                            newY = newY - 1
                            startY = startY - 1
                        elif newY < 0:
                            next = Vector2(startX,startY)
                            newY = newY + 1
                            startY = startY + 1
                        set_cellv(next, _tileset.find_tile_by_name(name))
                    if newY == 0:
                        next = Vector2(startX,startY)
                        set_cellv(next, _tileset.find_tile_by_name(name))
                    newX = newX - 1
                    startX = startX - 1
                elif newX < 0:
                    while (newY != 0):
                        if newY > 0:
                            next = Vector2(startX,startY)
                            newY = newY - 1
                            startY = startY - 1
                        elif newY < 0:
                            next = Vector2(startX,startY)
                            newY = newY + 1
                            startY = startY + 1
                        set_cellv(next, _tileset.find_tile_by_name(name))
                    if newY == 0:
                        next = Vector2(startX,startY)
                        set_cellv(next, _tileset.find_tile_by_name(name))
                    newX = newX + 1
                    startX = startX + 1
            if newX == 0:
                var newY = dragStart.y - tile_pos.y
                var startY = dragStart.y
                while (newY != 0):
                    if newY > 0:
                        next = Vector2(startX,startY)
                        newY = newY - 1
                        startY = startY - 1
                    elif newY < 0:
                        next = Vector2(startX,startY)
                        newY = newY + 1
                        startY = startY + 1
                    set_cellv(next, _tileset.find_tile_by_name(name))
                if newY == 0:
                    next = Vector2(startX,startY)
                    set_cellv(next, _tileset.find_tile_by_name(name))
    elif (button == 0 && dragStart != Vector2(-1,-1)):
        var name = _tileset.tile_get_name(15)
        var tile_pos = world_to_map(event.position)
        if (dragStart != Vector2(-1,-1) && dragStart != tile_pos):
            var newX = dragStart.x - tile_pos.x
            var next = Vector2(-1,-1)
            var startX = dragStart.x
            while (newX != 0):
                var newY = dragStart.y - tile_pos.y
                var startY = dragStart.y
                if newX > 0:
                    while (newY != 0):
                        if newY > 0:
                            next = Vector2(startX,startY)
                            newY = newY - 1
                            startY = startY - 1
                        elif newY < 0:
                            next = Vector2(startX,startY)
                            newY = newY + 1
                            startY = startY + 1
                        set_cellv(next, _tileset.find_tile_by_name(name))
                    if newY == 0:
                        next = Vector2(startX,startY)
                        set_cellv(next, _tileset.find_tile_by_name(name))
                    newX = newX - 1
                    startX = startX - 1
                elif newX < 0:
                    while (newY != 0):
                        if newY > 0:
                            next = Vector2(startX,startY)
                            newY = newY - 1
                            startY = startY - 1
                        elif newY < 0:
                            next = Vector2(startX,startY)
                            newY = newY + 1
                            startY = startY + 1
                        set_cellv(next, _tileset.find_tile_by_name(name))
                    if newY == 0:
                        next = Vector2(startX,startY)
                        set_cellv(next, _tileset.find_tile_by_name(name))
                    newX = newX + 1
                    startX = startX + 1
            if newX == 0:
                var newY = dragStart.y - tile_pos.y
                var startY = dragStart.y
                while (newY != 0):
                    if newY > 0:
                        next = Vector2(startX,startY)
                        newY = newY - 1
                        startY = startY - 1
                    elif newY < 0:
                        next = Vector2(startX,startY)
                        newY = newY + 1
                        startY = startY + 1
                    set_cellv(next, _tileset.find_tile_by_name(name))
                if newY == 0:
                    next = Vector2(startX,startY)
                    set_cellv(next, _tileset.find_tile_by_name(name))
            dragStart = Vector2(-1,-1)
            #set_cellv(next, _tileset.find_tile_by_name(name))
    else:
        dragStart = Vector2(-1,-1)

This code will let you left-click and drag across the tilemap, filling each cell with a tile from the tile set, then changing the tiles in all of the cells to another tile when the button is released. Works great from what I can see, but if anyone has some pointers to improve performance or clean up my code, please share!