physics: ability to add/sub/mul/div. Closes #1819

mods/lord/Core/physics/src/physics/PlayerPhysics.lua

@@ -1,5 +1,5 @@
-local table_merge, setmetatable
-	= table.merge, setmetatable
+local table_merge, table_add_values, table_sub_values, table_mul_values, table_div_values, setmetatable
+	= table.merge, table.add_values, table.sub_values, table.mul_values, table.div_values, setmetatable
 
 local Event = require('physics.Event')
 
@@ -37,24 +37,55 @@ function PlayerPhysics:refresh_player(player)
 	return self
 end
 
---- @param physics table
-function PlayerPhysics:set(physics)
-	self.physics = table_merge(self.physics, physics)
+--- @overload fun()
+--- @param name string
+--- @return number|table<string,number>
+function PlayerPhysics:get(name)
+	return name
+		and (self.physics[name] or nil)
+		or  self.physics
+end
 
+--- @private
+function PlayerPhysics:set_override()
 	self.player:set_physics_override(table_merge(
 		self.player:get_physics_override(), self.physics
 	))
+end
 
+--- @param physics physics_override_table
+function PlayerPhysics:set(physics)
+	self.physics = table_merge(self.physics, physics)
+	self:set_override()
 	Event:trigger(Event.Type.on_change, self.player, self)
 end
 
---- @overload fun()
---- @param name string
---- @return number|table<string,number>
-function PlayerPhysics:get(name)
-	return name
-		and (self.physics[name] or nil)
-		or  self.physics
+--- @param physics physics_override_table
+function PlayerPhysics:add(physics)
+	self.physics = table_add_values(self.physics, physics)
+	self:set_override()
+	Event:trigger(Event.Type.on_change, self.player, self)
+end
+
+--- @param physics physics_override_table
+function PlayerPhysics:sub(physics)
+	self.physics = table_sub_values(self.physics, physics)
+	self:set_override()
+	Event:trigger(Event.Type.on_change, self.player, self)
+end
+
+--- @param physics physics_override_table
+function PlayerPhysics:mul(physics)
+	self.physics = table_mul_values(self.physics, physics)
+	self:set_override()
+	Event:trigger(Event.Type.on_change, self.player, self)
+end
+
+--- @param physics physics_override_table
+function PlayerPhysics:div(physics)
+	self.physics = table_div_values(self.physics, physics)
+	self:set_override()
+	Event:trigger(Event.Type.on_change, self.player, self)
 end