create-new-affect

name	create-new-affect
description	How to create a new type of affect

Background information

Affects are functions that update an objects state. Examples include velocity, which causes an object to move in a particular direction, and bounce, which causes the object to bounce off of the edges of the game world.

Creating a new affect

• Review the circle game object's velocity affect as an example:
  • Definition: src/game/affect.velocity.ts
  • Usage: src/game/object.circle.ts
• The affect should define a state object in src/game/type.object.ts which extends AffectState and sets the category property to the z.literal of the newly defined category.
• Choose a name for the game affect based on the it's behavior.
• Add the name to the AffectCategory enum in src/game/game.affect.ts
• Create the file src/game/affect.some-new-affect.ts with an exported function that implements the affect interface as defined in src/game/game.affect.ts.
• The affect function should be implemented based on the needed behavior.
• Update the updateState method in the src/game/game.object.ts to apply the new affect.

export const BounceState = AffectState.extend({
  category: z.literal(AffectCategory.enum.Bounce),
});
export type BounceState = z.infer<typeof BounceState>;

Notes

• Some affects update other affects. Review the target affect for an example of this.
• Some affects interact with game object properties directly. Review the velocity affect for an example of this.
• Some affects use game world properties. Review the bounce affect for an example of this.
• The state for the new affect can include other values, such as strength of gravity, xy coordinates, dx dy velocity, or whatever is needed for that affect.