#region File Description
//-----------------------------------------------------------------------------
// Gem.cs
//
// Microsoft XNA Community Game Platform
// Copyright (C) Microsoft Corporation. All rights reserved.
//-----------------------------------------------------------------------------
#endregion
using System;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Audio;
namespace Platformer
{
///
/// A valuable item the player can collect.
///
class Gem
{
private Texture2D texture;
private Vector2 origin;
private SoundEffect collectedSound;
public const int PointValue = 30;
public readonly Color Color = Color.Yellow;
// The gem is animated from a base position along the Y axis.
private Vector2 basePosition;
private float bounce;
public Level Level
{
get { return level; }
}
Level level;
///
/// Gets the current position of this gem in world space.
///
public Vector2 Position
{
get
{
return basePosition + new Vector2(0.0f, bounce);
}
}
///
/// Gets a circle which bounds this gem in world space.
///
public Circle BoundingCircle
{
get
{
return new Circle(Position, Tile.Width / 3.0f);
}
}
///
/// Constructs a new gem.
///
public Gem(Level level, Vector2 position)
{
this.level = level;
this.basePosition = position;
LoadContent();
}
///
/// Loads the gem texture and collected sound.
///
public void LoadContent()
{
texture = Level.Content.Load("Sprites/Gem");
origin = new Vector2(texture.Width / 2.0f, texture.Height / 2.0f);
collectedSound = Level.Content.Load("Sounds/GemCollected");
}
///
/// Bounces up and down in the air to entice players to collect them.
///
public void Update(GameTime gameTime)
{
// Bounce control constants
const float BounceHeight = 0.18f;
const float BounceRate = 3.0f;
const float BounceSync = -0.75f;
// Bounce along a sine curve over time.
// Include the X coordinate so that neighboring gems bounce in a nice wave pattern.
double t = gameTime.TotalGameTime.TotalSeconds * BounceRate + Position.X * BounceSync;
bounce = (float)Math.Sin(t) * BounceHeight * texture.Height;
}
///
/// Called when this gem has been collected by a player and removed from the level.
///
///
/// The player who collected this gem. Although currently not used, this parameter would be
/// useful for creating special powerup gems. For example, a gem could make the player invincible.
///
public void OnCollected(Player collectedBy)
{
collectedSound.Play();
}
///
/// Draws a gem in the appropriate color.
///
public void Draw(GameTime gameTime, SpriteBatch spriteBatch)
{
spriteBatch.Draw(texture, Position, null, Color, 0.0f, origin, 1.0f, SpriteEffects.None, 0.0f);
}
}
}