From b8145c5471aa6e691daea16c0e410567bbfe8c00 Mon Sep 17 00:00:00 2001
From: LeMagnesium <mg.minetest@gmail.com>
Date: Sun, 4 Dec 2016 14:04:54 +0100
Subject: [PATCH] [mobs] Avoid server crash with nan vector values

---
 mods/mobs/api.lua | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/mods/mobs/api.lua b/mods/mobs/api.lua
index d87b1845..212998fb 100755
--- a/mods/mobs/api.lua
+++ b/mods/mobs/api.lua
@@ -476,6 +476,15 @@ do_jump = function(self)
 end
 
 function calc_velocity(pos1, pos2, old_vel, power) --MFF we use this function
+	-- If the two positions are equal the vector will contain nan and crash the game
+	if (pos1.x == pos2.x and pos1.y == pos2.y and pos1.z == pos2.z) then
+		return {
+			x = 0,
+			y = 0,
+			z = 0
+		}
+	end
+
 	local vel = vector.direction(pos1, pos2)
 	vel = vector.normalize(vel)
 	vel = vector.multiply(vel, power)