Adding random object every time you press the same key

Question

I'd like to make one spawnpoint that, adds a different/random object every time on pressing of the same key (space bar for example). This tutorial explains nicely, How you can make random objects appear with an Always-sensor from a 'list' in the python script. But when I change it to a Keyboard-sensor, it doesn't work.

Any ideas on how I can fix the script so it spawns random object with every keystroke? Or is there a way I can link multiple 'EditObject-actuators that each add different objects' to one Keyboard-sensor... and somehow give random priorities to those?

This is the final result I'm trying to achieve, only pressing 1 key.

Thanks in advance!

Answer 1

When you add a sensor, you need to eval if its active in the script so you can do stuff.

To evalute the keyboard sensor named "Keyboard"

from bge import logic
import random

keysensor = logic.getCurrentController().sensors['Keyboard']
scene = logic.getCurrentScene()
own = logic.getCurrentController().owner
list = ['Cube','etc']
'''Eval if sensor activated'''
if keysensor.positive:
    choice = random.choice(list)
    scene.addObject(choise, own, 100)

EDIT

To properly use scene.addObject the object has to be in an inactive layer see objectsInactive

And the script to work properly.

from bge import logic
import random

keysensor = logic.getCurrentController().sensors['Keyboard']
scene = logic.getCurrentScene()
own = logic.getCurrentController().owner
list = scene.objectsInactive
'''Eval if sensor activated'''
if keysensor.positive:
    choice = random.choice(list)
    scene.addObject(choice, own, 100)

ObjectsInactive is a list of all objects who are in an inactive layer, so if you need just some of the objects yo can add a property to the objects so you can gather them easy.

Then change

list = scene.objectsInactive

for

list = [obj for obj in scene.objectsInactive if 'spawnObj' in obj.getPropertyNames()]

That way the list would be fill with objects that have a property named "spawnObj".

Finally use descriptive names for the sensors, instead keyboard, keyboard.001, keyboard.002, ect... SpaceKey, aKey, BKEY, ckey, etc..

Demo file:

Answer 2

Adding via Keyboard sensor (or any other sensor)

I suggest to replace the always sensor with a keyboard sensor.

Disable [True Level Triggering] otherwise you will get new objects as long as you hold the key.

To avoid creating objects when releasing the key you need to check the sensor status. As I do not have the code from tutorial here is a different version of it.

import bge
import random

controller = bge.logic.getCurrentController()
if all(sensor.positive for sensor in controller.sensors):
    positionProvider = controller.owner
    templateNames = ["Sphere", "Cube"]
    templateName = random.choice(templateNames)

    addedObject = positionProvider.scene.addObject(templateName, positionProvider, 100)
    addedObject.setLinearVelocity(1.0, 0.0, 0.0)

Please notice I removed unnecessary code (such as main()) and use more descriptive names by avoiding cryptic abbreviations.

Automatically find template objects

For easier configuration you can read the available template objects directly from the scene:

import bge
import random

controller = bge.logic.getCurrentController()
if all(sensor.positive for sensor in controller.sensors):
    positionProvider = controller.owner
    scene = positionProvider.scene

    templates = scene.objectsInactive
    template = random.choice(templates)

    addedObject = scene.addObject(template, positionProvider, 100)
    addedObject.setLinearVelocity(1.0, 0.0, 0.0)

Template objects by property

When you have several emitters you can filter templates by property. Keep in mind one object can have several properties. This means you can configure an object that it gets added by different emitters.

The emitter needs a property called "filter" as String with the name of the property to look for. The objects at the hidden layer need a property with that name (the type and value are irrelevant).

import bge
import random

controller = bge.logic.getCurrentController()
if all(sensor.positive for sensor in controller.sensors):
    positionProvider = controller.owner
    scene = positionProvider.scene

    filterProperty = controller.owner.get("filter")

    templates = [template for template in scene.objectsInactive
                    if filterProperty is None or 
                       filterProperty in template]
    template = random.choice(templates)

    scene.addObject(template, positionProvider, 100)

Examples:

Your hidden layers contain this objects:

• flame.001 property "flame"
• flame.002 property "flame"
• spark.001 property "flame", "spark"
• smoke.001 property "smoke"

Your emitter has a property "filter" with value "flame". When you trigger the emitter it will emit one object out of flame.001, flame.002 or spark.001. It will never emit smoke.001.

When you have another emitter with property "filter" set to "smoke" it will emit smoke.001 only.

When you have an emitter without property "filter" it will emit from all template objects.

When you have an emitter with property "filter" set to "fog" it will result in error as there is no matching template object at the hidden layers.