TNT: Add explode_center flag

Add 'explode_centre' flag which when false explodes as normal and when true runs on_blast on centre node as well as dropping items.

game_api.txt

@@ -363,7 +363,8 @@ TNT API
 ^ Create an explosion.
 
 * `position` The center of explosion.
-* `definition` The TNT definion as passed to `tnt.register`
+* `definition` The TNT definion as passed to `tnt.register` with the following addition:
+ * `explode_center` false by default which removes TNT node on blast, when true will explode center node.
 
 `tnt.burn(position, [nodename])`
 

mods/tnt/init.lua

@@ -208,6 +208,7 @@ local function add_effects(pos, radius, drops)
 		collisiondetection = false,
 		vertical = false,
 		texture = "tnt_boom.png",
+		glow = 15,
 	})
 	minetest.add_particlespawner({
 		amount = 64,
@@ -272,7 +273,7 @@ function tnt.burn(pos, nodename)
 	end
 end
 
-local function tnt_explode(pos, radius, ignore_protection, ignore_on_blast, owner)
+local function tnt_explode(pos, radius, ignore_protection, ignore_on_blast, owner, explode_center)
 	pos = vector.round(pos)
 	-- scan for adjacent TNT nodes first, and enlarge the explosion
 	local vm1 = VoxelManip()
@@ -286,6 +287,10 @@ local function tnt_explode(pos, radius, ignore_protection, ignore_on_blast, owne
 	local c_tnt_burning = minetest.get_content_id("tnt:tnt_burning")
 	local c_tnt_boom = minetest.get_content_id("tnt:boom")
 	local c_air = minetest.get_content_id("air")
+	-- make sure we still have explosion even when centre node isnt tnt related
+	if explode_center then
+		count = 1
+	end
 
 	for z = pos.z - 2, pos.z + 2 do
 	for y = pos.y - 2, pos.y + 2 do
@@ -384,12 +389,14 @@ end
 function tnt.boom(pos, def)
 	local meta = minetest.get_meta(pos)
 	local owner = meta:get_string("owner")
+	if not def.explode_center then
+		minetest.set_node(pos, {name = "tnt:boom"})
+	end
 	local sound = def.sound or "tnt_explode"
 	minetest.sound_play(sound, {pos = pos, gain = 1.5,
 			max_hear_distance = math.min(def.radius * 20, 128)})
-	minetest.set_node(pos, {name = "tnt:boom"})
 	local drops, radius = tnt_explode(pos, def.radius, def.ignore_protection,
-			def.ignore_on_blast, owner)
+			def.ignore_on_blast, owner, def.explode_center)
 	-- append entity drops
 	local damage_radius = (radius / def.radius) * def.damage_radius
 	entity_physics(pos, damage_radius, drops)