186 lines
4.0 KiB
JavaScript
186 lines
4.0 KiB
JavaScript
"use strict";
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import Vector2D from "./vector2d.js";
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class Entity {
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constructor (x, y) {
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this.pos = new Vector2D(x || 0, y || 0);
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this.velocity = new Vector2D(0, 0);
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this.acceleration = new Vector2D(0, 0);
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this.state = {};
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this.children = [];
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this._calculatedPos = this.pos.clone();
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this._lastCalculated = 0;
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this._game = null;
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this._parent = null;
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this._creationTime = +(new Date());
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}
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setVelocity (x, y) {
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if (x instanceof Vector2D) {
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this.velocity = x;
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} else {
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this.velocity.x = x;
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this.velocity.y = y;
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}
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}
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setAcceleration (x, y) {
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if (x instanceof Vector2D) {
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this.acceleration = x;
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} else {
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this.acceleration.x = x;
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this.acceleration.y = y;
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}
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}
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createChildEntity () {
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let child = new Entity();
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child._updateGame(this._game);
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child._parent = this;
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this.children.push(child);
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return child;
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}
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addChildEntity (child) {
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child._updateGame(this._game);
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child._parent = this;
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this.children.push(child);
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return child;
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}
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detachChildEntity (child) {
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for (let i = 0; i < this.children.length; i++) {
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if (this.children[i] == child) {
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this.children.splice(i, 1);
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return true;
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}
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}
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return false;
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}
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_preprocess () {
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// NK: The purpose of this function is to calculate the true position of the entity relative to all its parents. It does this recursively, calling the _preprocess method all the way back up the tree and continuously adding the results together.
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// Note there is a limiter, where the last calculated frame is stored, so that if the position has already been calculated for that node in this particular frame, the cached result is used rather than recalculating.
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// When rendering, the draw calls should use this._calculatedPos rather than this.pos in order for the position to be correct.
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if (this._game && this._lastCalculated < this._game.frameCounter) {
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if (this._parent) {
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let parentPos = this._parent._preprocess();
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this._calculatedPos.x = this.pos.x + parentPos.x;
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this._calculatedPos.y = this.pos.y + parentPos.y;
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} else {
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this._calculatedPos.x = this.pos.x;
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this._calculatedPos.y = this.pos.y;
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}
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this._lastCalculated = this._game.frameCounter;
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}
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return this._calculatedPos;
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}
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_updateGame (game) {
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this._game = game;
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this.children.forEach((child) => {
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child._updateGame(game);
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});
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}
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_updateEntity (delta) {
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if (this.timeToLive) {
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if (+(new Date()) - this._creationTime > this.timeToLive) {
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this._parent.detachChildEntity(this);
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}
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}
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// Calculate new position based on velocity and acceleration if there's one set
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if (this.velocity) {
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if (this.acceleration) {
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this.velocity.add(this.acceleration);
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}
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this.pos.add(this.velocity);
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}
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// If there's an update method, call it
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let updated = this.update && this.update(delta);
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if (updated || (typeof updated == "undefined") || (typeof this.update === "undefined")) {
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this.children.forEach((child) => {
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child._updateEntity(delta);
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});
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}
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}
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_renderEntity () {
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this._preprocess();
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let rendered = this.render && this.render();
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if (rendered || (typeof rendered == "undefined") || (typeof this.render === "undefined")) {
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this.children.forEach((child) => {
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child._renderEntity();
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});
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}
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}
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}
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export default Entity; |