Changed how isometric grid is drawn

Instead of drawing individual lines, execute draw_isometric_tile() multiple times. What this method does is basically draws a single isometric tile, which then gets repeated for the entire canvas size. Also moved all the grid logic to a new script, which gets updated less often that Canvas.gd, for optimization purposes.

Works better than the previous method, although it might be a bit slower, and currently does not work well if the canvas size is not divisible by the grid size. For now, it only gets affected by the grid width. Changing grid height has no effect.

src/UI/Grid.gd

@@ -0,0 +1,53 @@
+extends Node2D
+
+
+var location := Vector2.ZERO
+var isometric_polylines := [] # An array of PoolVector2Arrays
+
+
+func _draw() -> void:
+	if Global.draw_grid:
+		draw_grid(Global.grid_type)
+
+
+func draw_grid(grid_type : int) -> void:
+	var size : Vector2 = Global.current_project.size
+	if grid_type == Global.Grid_Types.CARTESIAN || grid_type == Global.Grid_Types.ALL:
+		for x in range(Global.grid_width, size.x, Global.grid_width):
+			draw_line(Vector2(x, location.y), Vector2(x, size.y), Global.grid_color, true)
+
+		for y in range(Global.grid_height, size.y, Global.grid_height):
+			draw_line(Vector2(location.x, y), Vector2(size.x, y), Global.grid_color, true)
+
+	# Doesn't work properly yet
+	# Has problems when the canvas isn't a square, and with some grid sizes
+	if grid_type == Global.Grid_Types.ISOMETRIC || grid_type == Global.Grid_Types.ALL:
+		var i := 0
+		for x in range(Global.grid_width, size.x, Global.grid_width * 2):
+			for y in range(0, size.y, Global.grid_width):
+				draw_isometric_tile(i, Vector2(x, y))
+				i += 1
+
+
+func draw_isometric_tile(i : int, origin := Vector2.RIGHT) -> void:
+	# A random value I found by trial and error, I have no idea why it "works"
+	var diff = 1.11754
+	var approx_30_degrees = deg2rad(26.565)
+
+	var pool := PoolVector2Array()
+	if i < isometric_polylines.size():
+		pool = isometric_polylines[i]
+	else:
+		var a = origin
+		var b = a + Vector2(cos(approx_30_degrees), sin(approx_30_degrees)) * Global.grid_width * diff
+		var c = a + Vector2.DOWN * Global.grid_width
+		var d = c - Vector2(cos(approx_30_degrees), sin(approx_30_degrees)) * Global.grid_width * diff
+		pool.append(a)
+		pool.append(b)
+		pool.append(c)
+		pool.append(d)
+		pool.append(a)
+		isometric_polylines.append(pool)
+
+	if pool.size() > 2:
+		draw_polyline(pool, Global.grid_color)

src/UI/TopMenuContainer.gd

@@ -251,6 +251,7 @@ func toggle_tile_mode() -> void:
 func toggle_show_grid() -> void:
 	Global.draw_grid = !Global.draw_grid
 	view_menu.set_item_checked(1, Global.draw_grid)
+	Global.canvas.grid.update()
 
 
 func toggle_show_rulers() -> void: