Adds conical spells from TG (#27979)

* Adds conical spells from TG

* Remove testing stuff

* Errant whitespace

* Fix levels

code/datums/spell_targeting/cone.dm

@@ -0,0 +1,74 @@
+/datum/spell_targeting/cone
+	max_targets = INFINITY
+	use_intercept_click = TRUE
+	/// This controls how many levels the cone has. Increase this value to make a bigger cone.
+	var/cone_levels = 3
+	/// This value determines if the cone penetrates walls.
+	var/respect_density = FALSE
+
+/datum/spell_targeting/cone/choose_targets(mob/user, datum/spell/spell, params, atom/clicked_atom)
+	var/list/turfs_to_return = list()
+	var/turf/turf_to_use = get_turf(user)
+	var/turf/left_turf
+	var/turf/right_turf
+	var/dir_to_use = get_dir(user, clicked_atom)
+	var/right_dir
+	var/left_dir
+	switch(dir_to_use)
+		if(NORTH)
+			left_dir = WEST
+			right_dir = EAST
+		if(SOUTH)
+			left_dir = EAST
+			right_dir = WEST
+		if(EAST)
+			left_dir = NORTH
+			right_dir = SOUTH
+		if(WEST)
+			left_dir = SOUTH
+			right_dir = NORTH
+
+	// Go though every level of the cone levels and generate the cone.
+	for(var/level in 1 to cone_levels)
+		var/list/level_turfs = list()
+		// Our center turf always exists, it's straight ahead of the caster.
+		turf_to_use = get_step(turf_to_use, dir_to_use)
+		level_turfs += turf_to_use
+		// Level 1 only ever has 1 turf, it's a cone.
+		if(level != 1)
+			var/level_width_in_each_direction = round((calculate_cone_shape(level) - 1) / 2)
+			left_turf = turf_to_use
+			right_turf = turf_to_use
+			// Check turfs to the left...
+			for(var/left_of_center in 1 to level_width_in_each_direction)
+				if(respect_density && left_turf.density)
+					break
+				left_turf = get_step(left_turf, left_dir)
+				level_turfs += left_turf
+			// And turfs to the right.
+			for(var/right_of_enter in 1 to level_width_in_each_direction)
+				if(respect_density && right_turf.density)
+					break
+				right_turf = get_step(right_turf, right_dir)
+				level_turfs += right_turf
+		// Add the list of all turfs on this level to the turfs to return
+		turfs_to_return += list(level_turfs)
+
+		// If we're at the last level, we're done
+		if(level == cone_levels)
+			break
+		// But if we're not at the last level, we should check that we can keep going
+		if(respect_density && turf_to_use.density)
+			break
+
+	return turfs_to_return
+
+/**
+ * Adjusts the width of the cone at the passed level.
+ * This is never called on the first level of the cone (level 1 is always 1 width)
+ *
+ * Return a number - the TOTAL width of the cone at the passed level.
+ */
+/datum/spell_targeting/cone/proc/calculate_cone_shape(current_level)
+	// Default formula: (1 (innate) -> 3 -> 5 -> 5 -> 7 -> 7 -> 9 -> 9 -> ...)
+	return current_level + (current_level % 2) + 1