A custom component for activating a particle emitter when a villager walks by an object in Foundation by Polymorph Games

componentProximityTrigger.lua

--[[---------------------------------------------------------------------------\
| ||\\    //||       /|¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯\ |
| || \\  // ||  (o_ / |                   CUSTOM COMPONENT                   | |
| ||  \\//  ||  //\/  |                         ----                         | |
| ||   \/   ||  V_/_  |                  PROXIMITY TRIGGER                   | |
| ||        ||        |‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗‗/ |
\---------------------------------------------------------------------------]]--

--[[ Anyone is free to use this code for their mods so long as
     credits are attributed to Minotorious in form of a link to
     his profile on mod.io: https://mod.io/members/minotorious ]]--

local proximity = foundation.createMod();

local COMP_PROXIMITY_TRIGGER = {
	TypeName = "COMP_PROXIMITY_TRIGGER",
	ParentType = "COMPONENT",
	Properties = {
		{ Name = "Emitting", Type = "boolean", Default = false },
		{ Name = "EmitterNodeName", Type = "string", Default = "NAME_OF_YOUR_EMITTER_NODE_IN_THE_FBX" }
	}
}

function COMP_PROXIMITY_TRIGGER:create()
	self.timer = 0
end

function COMP_PROXIMITY_TRIGGER:update()
    if self.timer >= 0 then
        local dt = self:getLevel():getDeltaTime()
        self.timer = self.timer - dt
    elseif self.timer < 0 then
        if self.Emitting == true then
            self:getOwner():getParent():forEachChild(
                function(child)
                    if child.Name == self.EmitterNodeName then
                        local emitter = child:getComponent("COMP_PARTICLE_EMITTER")
                        if emitter.IsEmitting == true then
                            emitter.IsEmitting = false
                            self.Emitting = false
                        end
                    end
                end
            )
        end
    end
    
    if self.Emitting == false then
        local pos1 = self:getOwner():getGlobalPosition()
        self:getLevel():getComponentManager("COMP_AGENT"):getAllComponent():forEach(
            function(comp)
                local pos2 = comp:getOwner():getGlobalPosition()
                
                local distance = math.sqrt( (pos1.x - pos2.x)^2 + (pos1.y - pos2.y)^2 + (pos1.z - pos2.z)^2 )
                
                if distance < 4 then
                    if self.timer <= 0 then
                        self.timer = 5
                        self:getOwner():getParent():forEachChild(
                            function(child)
                                if child.Name == self.EmitterNodeName then
                                    local emitter = child:getComponent("COMP_PARTICLE_EMITTER")
                                    if emitter.IsEmitting == false then
                                        emitter.IsEmitting = true
                                        self.Emitting = true
                                    end
                                end
                            end
                        )
                    end
                end
            end
        )
    end
end

proximity:registerClass(COMP_PROXIMITY_TRIGGER)