State & Logic
Tracked values and actions let you record player choices and drive conditional behaviour as a player progresses through a scenario.
Table of content
Scenario progress in VPS is managed by tracked values and actions.
Tracked Values
Tracked values are any values that you want to keep track of as the player progresses through the scenario. Some examples of useful tracked values are:
- A player's score
- Whether a specific choice has been made
- A character's health
- Some player input
To create a tracked value, press the State Variables button on the very left of the toolbar. On the modal, enter a name that describes what this value is tracking, the type of the value, and what the value should be initially (when the player first begins the scenario), and then press Create on the bottom right of the input section.
This table explains the different types:
| Name | Meaning | Example |
|---|---|---|
| String | A text value | A character's mood can be "happy", "sad" or "angry" |
| Number | A positive or negative number | A player's score |
| Boolean | A value that can be either true or false | Whether a player has visited a specific scene |
Actions
To make tracked values useful, you need to update them as the player progresses through the scenario. To do this, you need to add actions to scene elements, just like adding links. After selecting an element, press the plus button in the State Operations section on the right; a modal should appear. In this dialog box, select the tracked value you want to update and how to update it. This can be either:
- Set
- Add (number only)
Set will just set the tracked value to the value you specify in the input. For example, you might set the tracked value character mood to "happy". The add action will perform addition to the tracked value. To perform subtraction, use the add action with a negative value.
A good way to think of actions is as sentences in the order action type, tracked value, action value, scene element:
- Set the player-health to 0, when the player presses the wrong option.
- Set whether the player has-requested-scans to true, when the player presses the request scans button.
- Add to the player-score by 1, when the player presses the correct answer.
Displaying Tracked Values
To let the player know about their progress, you can embed a tracked value directly inside any text in the scene. Wrap the tracked value name in two dollar signs on each side: $$tracked-value$$. For example, if you were tracking player health using a tracked value called player-health, you could write:
Your current health is $$player-health$$ points
You can place this text in the top left of all your scenes so the player can always see it.
A more complex example would be tracking user input for prescribing medicine. You would have buttons with increment and decrement actions on a tracked value for the dosage of each medication, and a text box labelled $$medicine-x-dosage$$ above each pair of buttons. This way, you can create a numerical input within the scenario.
Next Steps
Tracked values can also control which Resources are visible to the player at any given point in the scenario.