shapez.io/src/js/game/buildings/belt_base.js

import { Loader } from "../../core/loader";
import { enumAngleToDirection, enumDirection, Vector } from "../../core/vector";
import { BeltComponent } from "../components/belt";
import { ItemAcceptorComponent } from "../components/item_acceptor";
import { ItemEjectorComponent } from "../components/item_ejector";
import { ReplaceableMapEntityComponent } from "../components/replaceable_map_entity";
import { Entity } from "../entity";
import { MetaBuilding } from "../meta_building";
import { GameRoot } from "../root";

export const arrayBeltVariantToRotation = [enumDirection.top, enumDirection.left, enumDirection.right];

export class MetaBeltBaseBuilding extends MetaBuilding {
    constructor() {
        super("belt");
    }

    getSilhouetteColor() {
        return "#777";
    }

    getName() {
        return "Belt";
    }

    getDescription() {
        return "Transports items, hold and drag to place multiple.";
    }

    getPreviewSprite(rotationVariant) {
        switch (arrayBeltVariantToRotation[rotationVariant]) {
            case enumDirection.top: {
                return Loader.getSprite("sprites/buildings/belt_top.png");
            }
            case enumDirection.left: {
                return Loader.getSprite("sprites/buildings/belt_left.png");
            }
            case enumDirection.right: {
                return Loader.getSprite("sprites/buildings/belt_right.png");
            }
            default: {
                assertAlways(false, "Invalid belt rotation variant");
            }
        }
    }

    getBlueprintSprite(rotationVariant) {
        switch (arrayBeltVariantToRotation[rotationVariant]) {
            case enumDirection.top: {
                return Loader.getSprite("sprites/blueprints/belt_top.png");
            }
            case enumDirection.left: {
                return Loader.getSprite("sprites/blueprints/belt_left.png");
            }
            case enumDirection.right: {
                return Loader.getSprite("sprites/blueprints/belt_right.png");
            }
            default: {
                assertAlways(false, "Invalid belt rotation variant");
            }
        }
    }

    getStayInPlacementMode() {
        return true;
    }

    getRotateAutomaticallyWhilePlacing() {
        return true;
    }

    /**
     * Creates the entity at the given location
     * @param {Entity} entity
     */
    setupEntityComponents(entity) {
        entity.addComponent(
            new BeltComponent({
                direction: enumDirection.top, // updated later
            })
        );

        entity.addComponent(
            new ItemAcceptorComponent({
                slots: [
                    {
                        pos: new Vector(0, 0),
                        directions: [enumDirection.bottom],
                    },
                ],
            })
        );

        entity.addComponent(
            new ItemEjectorComponent({
                slots: [
                    {
                        pos: new Vector(0, 0),
                        direction: enumDirection.top, // updated later
                    },
                ],
                instantEject: true,
            })
        );
        // Make this entity replaceabel
        entity.addComponent(new ReplaceableMapEntityComponent());
    }

    /**
     *
     * @param {Entity} entity
     * @param {number} rotationVariant
     */
    updateRotationVariant(entity, rotationVariant) {
        entity.components.Belt.direction = arrayBeltVariantToRotation[rotationVariant];
        entity.components.ItemEjector.slots[0].direction = arrayBeltVariantToRotation[rotationVariant];

        entity.components.StaticMapEntity.spriteKey = null;
    }

    /**
     * Computes optimal belt rotation variant
     * @param {GameRoot} root
     * @param {Vector} tile
     * @param {number} rotation
     * @return {{ rotation: number, rotationVariant: number }}
     */
    computeOptimalDirectionAndRotationVariantAtTile(root, tile, rotation) {
        const topDirection = enumAngleToDirection[rotation];
        const rightDirection = enumAngleToDirection[(rotation + 90) % 360];
        const bottomDirection = enumAngleToDirection[(rotation + 180) % 360];
        const leftDirection = enumAngleToDirection[(rotation + 270) % 360];

        const { ejectors, acceptors } = root.logic.getEjectorsAndAcceptorsAtTile(tile);

        let hasBottomEjector = false;
        let hasRightEjector = false;
        let hasLeftEjector = false;

        let hasTopAcceptor = false;
        let hasLeftAcceptor = false;
        let hasRightAcceptor = false;

        // Check all ejectors
        for (let i = 0; i < ejectors.length; ++i) {
            const ejector = ejectors[i];

            if (ejector.toDirection === topDirection) {
                hasBottomEjector = true;
            } else if (ejector.toDirection === leftDirection) {
                hasRightEjector = true;
            } else if (ejector.toDirection === rightDirection) {
                hasLeftEjector = true;
            }
        }

        // Check all acceptors
        for (let i = 0; i < acceptors.length; ++i) {
            const acceptor = acceptors[i];
            if (acceptor.fromDirection === bottomDirection) {
                hasTopAcceptor = true;
            } else if (acceptor.fromDirection === rightDirection) {
                hasLeftAcceptor = true;
            } else if (acceptor.fromDirection === leftDirection) {
                hasRightAcceptor = true;
            }
        }

        // Soo .. if there is any ejector below us we always prioritize
        // this ejector
        if (!hasBottomEjector) {
            // When something ejects to us from the left and nothing from the right,
            // do a curve from the left to the top

            if (hasRightEjector && !hasLeftEjector) {
                return {
                    rotation: (rotation + 270) % 360,
                    rotationVariant: 2,
                };
            }

            // When something ejects to us from the right and nothing from the left,
            // do a curve from the right to the top
            if (hasLeftEjector && !hasRightEjector) {
                return {
                    rotation: (rotation + 90) % 360,
                    rotationVariant: 1,
                };
            }
        }

        // When there is a top acceptor, ignore sides
        // NOTICE: This makes the belt prefer side turns *way* too much!
        if (!hasTopAcceptor) {
            // When there is an acceptor to the right but no acceptor to the left,
            // do a turn to the right
            if (hasRightAcceptor && !hasLeftAcceptor) {
                return {
                    rotation,
                    rotationVariant: 2,
                };
            }

            // When there is an acceptor to the left but no acceptor to the right,
            // do a turn to the left
            if (hasLeftAcceptor && !hasRightAcceptor) {
                return {
                    rotation,
                    rotationVariant: 1,
                };
            }
        }

        return {
            rotation,
            rotationVariant: 0,
        };
    }
}