95 lines
3.0 KiB
TypeScript
95 lines
3.0 KiB
TypeScript
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import { System, SystemNames } from ".";
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import {
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Acceleration,
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BoundingBox,
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ComponentNames,
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Forces,
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Gravity,
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Velocity,
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Mass,
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Jump,
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} from "../components";
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import { PhysicsConstants } from "../config";
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import type { Entity } from "../entities";
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import type { Force2D } from "../interfaces";
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export class Physics extends System {
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constructor() {
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super(SystemNames.Physics);
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}
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public update(
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dt: number,
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entityMap: Map<number, Entity>,
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componentEntities: Map<string, Set<number>>
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): void {
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componentEntities.get(ComponentNames.Forces)?.forEach((entityId) => {
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const entity = entityMap.get(entityId);
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const mass = entity.getComponent<Mass>(ComponentNames.Mass).mass;
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const forces = entity.getComponent<Forces>(ComponentNames.Forces).forces;
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const velocity = entity.getComponent<Velocity>(ComponentNames.Velocity);
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const inertia = entity.getComponent<Moment>(
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ComponentNames.Moment
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).inertia;
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// F_g = mg, applied only until terminal velocity is reached
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if (entity.hasComponent(ComponentNames.Gravity)) {
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const gravity = entity.getComponent<Gravity>(ComponentNames.Gravity);
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if (velocity.dCartesian.dy <= gravity.terminalVelocity) {
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forces.push({
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fCartesian: {
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fy: mass * PhysicsConstants.GRAVITY,
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},
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});
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}
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}
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// ma = Σ(F), Iα = Σ(T)
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const sumOfForces = forces.reduce(
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(accum: Force2D, { fCartesian, torque }: Force2D) => ({
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fCartesian: {
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fx: accum.fCartesian.fx + (fCartesian?.fx ?? 0),
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fy: accum.fCartesian.fy + (fCartesian?.fy ?? 0),
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},
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torque: accum.torque + (torque ?? 0),
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}),
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{ fCartesian: { fx: 0, fy: 0 }, torque: 0 }
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);
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// integrate accelerations
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const [ddy, ddx] = [
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sumOfForces.fCartesian.fy,
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sumOfForces.fCartesian.fx,
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].map((x) => x / mass);
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velocity.dCartesian.dx += ddx * dt;
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velocity.dCartesian.dy += ddy * dt;
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velocity.dTheta += (sumOfForces.torque * dt) / inertia;
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// clear the forces
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entity.getComponent<Forces>(ComponentNames.Forces).forces = [];
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// maybe we fell off the floor
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if (ddy > 0 && entity.hasComponent(ComponentNames.Jump)) {
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entity.getComponent<Jump>(ComponentNames.Jump).canJump = false;
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}
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});
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componentEntities.get(ComponentNames.Velocity)?.forEach((entityId) => {
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const entity = entityMap.get(entityId);
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const velocity = entity.getComponent<Velocity>(ComponentNames.Velocity);
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const boundingBox = entity.getComponent<BoundingBox>(
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ComponentNames.BoundingBox
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);
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// integrate velocity
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boundingBox.center.x += velocity.dCartesian.dx * dt;
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boundingBox.center.y += velocity.dCartesian.dy * dt;
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boundingBox.rotation += velocity.dTheta * dt;
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boundingBox.rotation =
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(boundingBox.rotation < 0
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? 360 + boundingBox.rotation
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: boundingBox.rotation) % 360;
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});
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}
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}
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