LocalTransform2D

The LocalTransform2D component allows the entity to be positioned in 2D space.

LocalTransform2D only stores the local (parent-space) transform data. If the entity is a top-level entity, the local data is also the world-space data.

In order to be a parent of other entities, or to be a child of another entity, the entity must also have the SpatialNode2D component.

OTOH, entities with LocalTransform2D but without SpatialNode2D have their model matrix computed in the shader, making them very fast to update.

For an entity to be processed by sys_transform2d, it must also be tagged as dirty with Has.Dirty.

View source on GitHub

import {Deg, Vec2} from "../../lib/math.js";
import {vec2_copy} from "../../lib/vec2.js";
import {Entity} from "../../lib/world.js";
import {Game} from "../game.js";
import {Has} from "../world.js";

export interface LocalTransform2D {
    /** Local translation relative to the parent. */
    Translation: Vec2;
    /** Local rotation relative to the parent. */
    Rotation: Deg;
    /** Local scale relative to the parent. */
    Scale: Vec2;
}

Add LocalTransform2D to an entity.

LocalTransform2D component only stores the local (parent-space) transform data. If the entity is a top-level entity, the local data is also the world-space data.

In order to be a parent of other entities, or to be a child of another entity, the entity must also have the SpatialNode2D component.

translation param: Local translation relative to the parent.
rotation param: Local rotation relative to the parent.
scale param: Local scale relative to the parent.

export function local_transform2d(
    translation: Vec2 = [0, 0],
    rotation: Deg = 0,
    scale: Vec2 = [1, 1]
) {
    return (game: Game, entity: Entity) => {
        game.World.Signature[entity] |= Has.LocalTransform2D | Has.Dirty;
        game.World.LocalTransform2D[entity] = {
            Translation: translation,
            Rotation: rotation,
            Scale: scale,
        };
    };
}

Set position in the entity's transform.