tobspr_shapez.io/src/js/game/components/belt.js

import { Math_cos, Math_PI, Math_sin } from "../../core/builtins";
import { enumDirection, Vector } from "../../core/vector";
import { types } from "../../savegame/serialization";
import { BeltPath } from "../belt_path";
import { Component } from "../component";
import { Entity } from "../entity";

export const curvedBeltLength = /* Math_PI / 4 */ 0.78;

export class BeltComponent extends Component {
    static getId() {
        return "Belt";
    }

    static getSchema() {
        // The followUpCache field is not serialized.
        return {
            direction: types.string,
        };
    }

    duplicateWithoutContents() {
        return new BeltComponent({ direction: this.direction });
    }

    /**
     *
     * @param {object} param0
     * @param {enumDirection=} param0.direction The direction of the belt
     */
    constructor({ direction = enumDirection.top }) {
        super();

        this.direction = direction;

        /** @type {Entity} */
        this.followUpCache = null;

        /**
         * The path this belt is contained in, not serialized
         * @type {BeltPath}
         */
        this.assignedPath = null;
    }

    /**
     * Returns the effective length of this belt in tile space
     * @returns {number}
     */
    getEffectiveLengthTiles() {
        return this.direction === enumDirection.top ? 1.0 : curvedBeltLength;
    }

    /**
     * Converts from belt space (0 = start of belt ... 1 = end of belt) to the local
     * belt coordinates (-0.5|-0.5 to 0.5|0.5)
     * @param {number} progress
     * @returns {Vector}
     */
    transformBeltToLocalSpace(progress) {
        switch (this.direction) {
            case enumDirection.top:
                assert(progress <= 1.02, "Invalid progress: " + progress);
                return new Vector(0, 0.5 - progress);

            case enumDirection.right: {
                assert(progress <= curvedBeltLength + 0.02, "Invalid progress 2: " + progress);
                const arcProgress = (progress / curvedBeltLength) * 0.5 * Math_PI;
                return new Vector(0.5 - 0.5 * Math_cos(arcProgress), 0.5 - 0.5 * Math_sin(arcProgress));
            }
            case enumDirection.left: {
                assert(progress <= curvedBeltLength + 0.02, "Invalid progress 3: " + progress);
                const arcProgress = (progress / curvedBeltLength) * 0.5 * Math_PI;
                return new Vector(-0.5 + 0.5 * Math_cos(arcProgress), 0.5 - 0.5 * Math_sin(arcProgress));
            }
            default:
                assertAlways(false, "Invalid belt direction: " + this.direction);
                return new Vector(0, 0);
        }
    }
}