pong-game/PongGame/Hubs/PongGameState.cs

116 lines
4.3 KiB
C#

using System.Drawing;
namespace PongGame.Hubs;
/// <summary>
/// Pong game state saving the positions of the paddles and the ball.
/// The Pong board has aspect ratio 1:2 with height 500 and width 1000.
/// </summary>
public struct PongGameState {
public const float HEIGHT = 500.0f;
public const float WIDTH = 2 * HEIGHT;
public const float PADDLE1_OFFSET = WIDTH / 20;
public const float PADDLE2_OFFSET = WIDTH - PADDLE1_OFFSET;
public static readonly PongGameState Initial = new() {
BallState = PongBallState.Initial,
Paddle1 = PongPaddleState.Initial,
Paddle2 = PongPaddleState.Initial,
Status = GameStatus.WaitingForPlayers,
WinnerLeft = null
};
public PongPaddleState Paddle1;
public PongPaddleState Paddle2;
public PongBallState BallState;
public GameStatus Status;
public bool? WinnerLeft;
public static void Update(ref PongGameState state) {
if (state.Status is not GameStatus.InProgress) return;
PongPaddleState.Update(ref state.Paddle1);
PongPaddleState.Update(ref state.Paddle2);
PongBallState.Update(ref state.BallState);
var ballX = state.BallState.Pos.X;
if (ballX is < 0 or > WIDTH) {
state.WinnerLeft = ballX < 0;
state.Status = GameStatus.Finished;
return;
}
Collide(in state.Paddle1, ref state.BallState, true);
Collide(in state.Paddle2, ref state.BallState, false);
}
private static void Collide(in PongPaddleState paddle, ref PongBallState ballState, bool left) {
var paddleX = left ? PADDLE1_OFFSET : PADDLE2_OFFSET;
var intersection = RectangleF.Intersect(paddle.GetCollider(paddleX), ballState.GetCollider());
if (intersection.IsEmpty) return;
// TODO: continuous collision
var ratio = (ballState.Pos.Y - paddle.Height + PongPaddleState.PADDLE_HALF_LENGTH) / PongPaddleState.PADDLE_LENGTH;
// TODO: lesser angles
var upAngle = left ? MathF.PI * 3 / 8 : MathF.PI * 5 / 8;
var downAngle = left ? -MathF.PI * 3 / 8 : MathF.PI * 11 / 8;
// TODO: reflect ball on surface instead of launching
ballState.BallAngle = ratio * downAngle + (1 - ratio) * upAngle;
}
public struct PongBallState {
public const float BALL_SPEED = 2 * BALL_RADIUS;
public const float BALL_RADIUS = HEIGHT / 125;
public static readonly PongBallState Initial = new() {
BallAngle = 0.0f,
Pos = new() {
X = WIDTH / 2,
Y = HEIGHT / 2
}
};
public PointF Pos;
public float BallAngle;
public static void Update(ref PongBallState state) {
var (dy, dx) = MathF.SinCos(state.BallAngle);
state.Pos.X += BALL_SPEED * dx;
state.Pos.Y -= BALL_SPEED * dy;
// If reflected from lower or upper border calculate continuous reflection
// This prevents the ball from temporarily glitching into paddles
if (state.Pos.Y < BALL_RADIUS) {
state.Pos.Y = 2 * BALL_RADIUS - state.Pos.Y;
state.BallAngle = 2 * MathF.PI - state.BallAngle;
} else if (state.Pos.Y > HEIGHT - BALL_RADIUS) {
state.Pos.Y = 2 * (HEIGHT - BALL_RADIUS) - state.Pos.Y;
state.BallAngle = 2 * MathF.PI - state.BallAngle;
}
}
public RectangleF GetCollider() => new(Pos.X - BALL_RADIUS, Pos.Y - BALL_RADIUS, 2 * BALL_RADIUS, 2 * BALL_RADIUS);
}
public struct PongPaddleState {
public const float PADDLE_LENGTH = HEIGHT / 10;
public const float PADDLE_HALF_LENGTH = PADDLE_LENGTH / 2;
public const float PADDLE_WIDTH = PADDLE_LENGTH / 5;
public const float PADDLE_SPEED = 8;
public static readonly PongPaddleState Initial = new() {
Direction = PongPaddleDirection.Stop,
Height = HEIGHT / 2
};
public float Height;
public PongPaddleDirection Direction;
public static void Update(ref PongPaddleState state) {
state.Height = Math.Clamp(state.Height - ((int)state.Direction) * PADDLE_SPEED, PADDLE_HALF_LENGTH, HEIGHT - PADDLE_HALF_LENGTH);
}
public RectangleF GetCollider(float x) => new(x - PADDLE_WIDTH / 2, Height - PADDLE_HALF_LENGTH, PADDLE_WIDTH, PADDLE_LENGTH);
}
}