Blueprint Communication - FOR THE LOVE OF GOD....HELP ME

[VagrantProfile]

is currently confusing the **** out of me and I’ve been watching tutorials for weeks. As far as I can tell, there are multiple ways to communicate between blueprints:

1. Custom Events
2. Blueprint Interfaces
3. Event Dispatchers

I understand HOW to implement each…BUT I HAVE NO IDEA WHEN TO USE WHICH FORM OF COMMUNICATION!!!. Best practices concerning these would be awesome.

ALSO, on a somewhat related topic…how the HELL do I reference (get or set) a variable from one blueprint (blueprint A) in ANOTHER blueprint (blueprint B?) I keep getting “variable not in scope” messages…

Any insight / info here will earn you a gold star, my friends…

[Fen]

Hello,
Sorry to be obvious but you use them when you need them ^^

For example : If you hit an enemy with a projectile, you need to know enemy hp. In your enemy blueprint you set a variable “hp”. And you need to know the damage you did. Those informations can be in your weapon and your projectile.

Then on hit, your projectile check from your character your variable weapon damage modifier and use it to modify your projectile damage.
Then it checks hit target “hp” (your enemy blueprint) and set new “hp” : “hp” - “damage modified”. Then it set in enemy blueprint (the hit target) a variable “wounded” to true.
And in your enemy blueprint you have an event : wounded = true : play anim “wounded” and sound “arggg”

To reference another blueprint : create a variable then in the list selection type the name of the blueprint. Select it. You have your reference.

[Nesjett]

There are no better choice as far as I know, you can use them as you whis.

A recent test said that is faster to use direct casting rather than interfaces (but just a few milliseconds)

(You forgot to mention casting as a way to comunnication between BPs)

Maybe using interfaces is better if you need to define some functions used on many BPs, but I did tons of thinks and never used interfaces.

The only you should worry about is to use custom events or functions, but is a modularity thopic, not really a “bets to use”

[anonymous_user_0df12f74]

The documentation on blueprint communication does provide some examples of which method to use in certain situations, it does not go over every use case, but here are some examples:

**Direct Blueprint Communication
**
Below are some examples when you might use Blueprint Comms:

• You have an Actor in your level that you want to communicate with another Actor in your level.

• Interacting with a switch in your level opens a specific door or turns on a specific light (each of which are separate Blueprints).

**Blueprint Casting
**
Here are a few examples when you could use Blueprint Casting:

• You have a character interact with an Actor in your level and in turn causes a change to the character in some way.

• Player picks up a health pack in the level, restoring health in the player character.

• Enemy walks in snow or mud, causing their movement speed to slow down.

• You want to pass variables to a HUD or UI Widget, Save Game, Controller or Game Mode.

• Passing player or enemy health from a Character Blueprint to a HUD or Widget Blueprint to display the value on screen.

• Passing variables (current health or energy, money, items or abilities) to a Save Game Blueprint so that they can be restored later.

• You have multiple Blueprints which are children of another Blueprint and you want to access one of the children.

• You have Cat, Dog and Bird Blueprints which share functionality from an Animal Blueprint. Using the Animal Blueprint, youCast To the Bird Blueprint to execute a “Flying” function.

• You have a Blueprint that is dependent on another Blueprint’s Variables, Events or Functions.

• Plugging a battery into a flashlight turns on the light and the intensity of the light is determined by a value in the battery.

• You want to access multiple Blueprints of the same class and modify them all the same way at once.

• You have several lights in your level and you want them all to turn on or off when an event occurs.

**Event Dispatchers

**The examples below would be a case where an Event Dispatcher could be used:

• You want to communicate from your character Blueprint to your Level Blueprint.

• Your player character levels up and you want to open a previously locked area.

• Your player character presses an action button that does something in your level.

• You want to have Events fired when a spawned Actor has something done to it.

• You spawn a boss and an Event is fired when the boss is killed which spawns a reward in the world.

• You spawn an item in your level (weapon, health, boost, etc.) and through an Event, notify the item and character when it is picked up.

**Blueprint Interfaces

**Each of the examples below are scenarios where a Blueprint Interface might be the best method of communication:

• You have some functionality in a Blueprint that can produce different results when interacted with or based off other variables you define.

• Player has a flamethrower that when used, fires an Event called ElementalDamage. A Tree Blueprint gets the call and burns the tree down while a Snowman Blueprint melts the snowman.

• Player has a “use” button, pressing the use button opens doors, turns off lights, picks up items, etc.

• Enemy has a special ability that changes based on player health.

Hope that helps!