tutorial2_5.md

Tutorial 2 - Part 5: Define the rules

In order to define the rules of the level, we will add a Ruleset object to level.js. See Ruleset documentation for more details on how to create rules for a level.

Win condition

Create a CustomWinCondition that implements the objective goal.

module.exports = {

  // mapConfig: ...
  // messages: ...
  // worldGenerator: ...

  ruleset: {
    // CustomWinCondition object
    win: {

      // This method is called during the level initialization
      beforeStart(world) {
        // Find the highest value of all the eggs
        let max = 0
        for (let egg of world.eggs) {
          max = Math.max(max, egg.value)
        }

        // Create a 'maxValue' property on this CustomWinCondition object
        // for later use in check()
        this.maxValue = max
      },

      // This method is called after each step of the game loop
      // It should return true if the player has won, false otherwise
      check(world) {
        // Get the ids of the items in the cauldron
        const cauldronItems = world.cauldrons[0].items
        if (cauldronItems.length !== 1) {
          return false
        }

        // Find the egg with this specific id and check if its value is the highest
        const eggInCauldron = world.findObjectByID(cauldronItems[0])
        return eggInCauldron.value === this.maxValue
      }
    },

    lose: ['default_loss']
  }
}

💡 Check out the level lifecycle to see when beforeStart() and check() are called.

Open the level in the game and check that the win condition works with this solution:

if w == wall :
	top_loop:
	select_max:
	if myitem == nothing ||
	  e > myitem :
		drop(here)
		take(e)
	endif
	if s != wall :
		step(s)
		jump select_max
	endif
	step(e)
	step(e)
	tell("ok" everyone)
	step(e)
	go_north:
	step(n)
	if n != wall :
		jump go_north
	endif
	if e != cauldron :
		jump top_loop
	endif
	drop(e)
endif
bottom_loop:
go_to_switch:
step(e)
if here != switch &&
  e == floor :
	jump go_to_switch
endif
listen("ok")
jump bottom_loop

It seams to be working fine. 👍

Loss conditions

For now, the loss conditions for the level are defined as lose: ['default_loss']. It means that it uses the default loss conditions. You lose if all the heroes die or if all the heroes are asleep or if the solution takes too much time to complete the objective. These default loss conditions make sense in most levels but we'd like to add some conditions in which the player can lose.

See LossConditions documentation to better understand how to create loss conditions for a level.

First we'd like the player to lose if only one hero dies.

  lose: ['one_hero_dead', 'or', 'default_loss']

You can test that the new loss conditions work with this solution:

if w == wall :
	a:
	step(e)
	jump a
endif

For now, when an egg which is not of highest value is dropped into the cauldron, the player doesn't lose, it just keeps going. We'd like to rectify this by creating a CustomLossCondition.

lose: [{
    // Returns an identifier of this CustomLossCondition.
    // It is used in messages property to define
    // the message to display when this condition is triggered.
    getReason(world) {
      return 'loss_reason_wrong_egg_in_cauldron'
    },

    // This method is called during the level initialization
    beforeStart(world) {
      // Find the highest value of all the eggs
      let max = 0
      for (let egg of world.eggs) {
        max = Math.max(max, egg.value)
      }

      // Create a 'maxValue' property on this CustomWinCondition object
      // for later use in check()
      this.maxValue = max
    },

    // This method is called after each step of the game loop
    // It should return true if the player has lost, false otherwise
    check(world) {
      // Get the ids of the items in the cauldron
      const cauldronItems = world.cauldrons[0].items
      if (cauldronItems.length === 0) {
        return false
      }

      // If at least one egg in the cauldron is not of highest value
      // return true.
      const eggsInCauldron = cauldronItems.map(eggID => world.findObjectByID(eggID))
      return eggsInCauldron.some(egg => egg.value < this.maxValue)
    }
  },
  'or',
  'one_hero_dead',
  'or',
  'default_loss'
]

We have to add a custom message to the messages property that will be displayed whenever this CustomLossCondition is triggered. We also add a warning in the objective to inform the player about this loss condition.

messages: {
  "en": {
    "name": "Black forest",
    "objective": "Put the %%icon icon-egg$%% egg of highest value into the %%icon icon-cauldron$%% cauldron.\n\n%%icon mdi mdi-alert-octagon-outline$%%Warning: don't put any other %%icon icon-egg$%% egg into the %%icon icon-cauldron$%% cauldron.",
    "loss_reason_wrong_egg_in_cauldron": "You put an %%icon icon-egg$%% egg which is not of highest value into the %%icon icon-cauldron$%% cauldron."
  },
  "fr": {
    "name": "Forêt noire",
    "objective": "Mets l'%%icon icon-egg$%% œuf de valeur maximale dans le %%icon icon-cauldron$%% chaudron.\n\n%%icon mdi mdi-alert-octagon-outline$%%Attention: ne mets pas d'autre %%icon icon-egg$%% œuf dans le %%icon icon-cauldron$%% chaudron.",
    "loss_reason_wrong_egg_in_cauldron": "Tu as mis un %%icon icon-egg$%% œuf qui n'est pas le maximum dans le %%icon icon-cauldron$%% chaudron."
  }
},

Let's test this CustomLossCondition in the game with the following code:

if w == wall :
	top_loop:
	select_min:
	if myitem == nothing ||
		e < myitem :
		drop(here)
		take(e)
	endif
	if s != wall :
		step(s)
		jump select_min
	endif
	step(e)
	step(e)
	tell("ok" everyone)
	step(e)
	go_north:
	step(n)
	if n != wall :
		jump go_north
	endif
	if e != cauldron :
		jump top_loop
	endif
	drop(e)
endif
bottom_loop:
go_to_switch:
step(e)
if here != switch &&
	e == floor :
	jump go_to_switch
endif
listen("ok")
jump bottom_loop

Next: ▶️ Part 6: Configure Selfless Heroes language capabilities