SpatialNode2D

The SpatialNode2D component allows the entity to be part of the 2D scene graph.

Only entities with SpatialNode2D can be parented to other entities, or be parents of other entities.

import {mat2d_create} from "../../lib/mat2d.js";
import {Mat2D} from "../../lib/math.js";
import {Entity} from "../../lib/world.js";
import {FLOATS_PER_INSTANCE} from "../../materials/layout2d.js";
import {Game} from "../game.js";
import {Has, World} from "../world.js";

export interface SpatialNode2D {
    /** Absolute matrix relative to the world. */
    World: Mat2D;
    /** World to self matrix. */
    Self: Mat2D;
    Parent?: Entity;
    /** Ignore parent's rotation and scale? */
    IsGyroscope: boolean;
}

Add SpatialNode2D to an entity.

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. It's also required if you're going to need to switch between the world space and the entity's self space, or if you're going to query the entity's parent.

Entities with LocalTransform2D and SpatialNode2D have their model matrix computed in sys_transform2d() on the CPU, making them slower than entities with only LocalTransform2D, but more fully-featured.

is_gyroscope param: Ignore parent's rotation and scale?

export function spatial_node2d(is_gyroscope = false) {
    return (game: Game, entity: Entity) => {
        game.World.Signature[entity] |= Has.SpatialNode2D | Has.Dirty;
        game.World.SpatialNode2D[entity] = {
            World: game.World.InstanceData.subarray(
                entity * FLOATS_PER_INSTANCE,
                entity * FLOATS_PER_INSTANCE + 6
            ),
            Self: mat2d_create(),
            IsGyroscope: is_gyroscope,
        };
    };
}

Yield ascendants matching a component mask. Start at the current entity.

world param: World object which stores the component data.
entity param: The first entity to test.
mask param: Component mask to look for.

export function* query_up(world: World, entity: Entity, mask: Has): IterableIterator<Entity> {
    if ((world.Signature[entity] & mask) === mask) {
        yield entity;
    }

    let parent = world.SpatialNode2D[entity].Parent;
    if (parent !== undefined) {
        yield* query_up(world, parent, mask);
    }
}