src/game/utils.ts


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import { Ball } from "../state";
import { VELOCITY_SCALING_FACTOR } from "./const";

export const applyBallVelocity = (ball: Ball): Ball => {
  let newPos = ball.position.map(
    (a, i) => a + ball.velocity[i] * VELOCITY_SCALING_FACTOR
  ) as [number, number];
  return { ...ball, position: newPos };
};

export const applyBallBounce = (ball: Ball, normal: [number, number]): Ball => {
  //calculate reflection
  const newVelocity = ball.velocity.map(
    (v, i) => v - v * Math.abs(normal[i]) * 2
  ) as [number, number];

  //move the ball out of the collider
  const newPos = ball.position.map((p, i) => p + normal[i]) as [number, number];

  //this gives a little punch
  let newBall = { velocity: newVelocity, position: newPos };
  newBall = applyBallVelocity(newBall);
  return newBall;
};