/// <summary>
/// Calculate the colission on a per pixel level
/// Looks at both pixel colors. If they are not transparent (the alpha channel is not 0),
/// then there is a collision.
/// </summary>
/// <param name="e1">Entity 1</param>
/// <param name="e2">Entity 2</param>
/// <returns></returns>
private bool PerPixelCollision(AnimatedEntity e1, AnimatedEntity e2)
{
var at = e1.Animation.Transformations;
var afw = e1.Animation.FrameWidth;
var afh = e1.Animation.FrameHeight;
var acd = e1.Animation.ColorData;
var bt = e2.Animation.Transformations;
var bfw = e2.Animation.FrameWidth;
var bfh = e2.Animation.FrameHeight;
var bcd = e2.Animation.ColorData;
/// Get Color data of each Texture
Color[] bitsA = new Color[afw * afh];
Color[] bitsB = new Color[bfw * bfh];
/// Calculate the intersecting rectangle
int x1 = Math.Max(e1.Bounds.X, e2.Bounds.X);
int x2 = Math.Min(e1.Bounds.X + e1.Bounds.Width, e2.Bounds.X + e2.Bounds.Width);
int y1 = Math.Max(e1.Bounds.Y, e2.Bounds.Y);
int y2 = Math.Min(e1.Bounds.Y + e1.Bounds.Height, e2.Bounds.Y + e2.Bounds.Height);
/// For each single pixel in the intersecting rectangle
for (int y = y1; y < y2; ++y)
{
for (int x = x1; x < x2; ++x)
{
/// Get the color from each texture
Color a = bitsA[(x - e1.Bounds.X) + (y - e1.Bounds.Y) * afw];
Color b = bitsB[(x - e2.Bounds.X) + (y - e2.Bounds.Y) * bfw];
/// If both colors are not transparent (the alpha channel is not 0), then there is a collision
if (a.A != 0 && b.A != 0)
{
return true;
}
}
}
/// If no collision occurred by now, we're clear.
return false;
}
/// <summary>
/// Handle a touch event with another entity.
/// This occurs when two entities collide
/// </summary>
/// <param name="other">The other entity that has been collided with</param>
public virtual void Touch(AnimatedEntity other)
{
}
/// <summary>
/// Handle collisions
/// </summary>
/// <param name="other">The other entity that collided with the asteroid.</param>
public override void Touch(AnimatedEntity other)
{
/// Check to see if the player got hit.
if (other is Player)
{
var player = other as Player;
if (!player.UnderProtection)
{
player.Kill();
}
}
base.Touch(other);
}
/// <summary>
/// Check if this entity has collided with another entity
/// </summary>
/// <param name="other"></param>
/// <returns></returns>
public bool CheckCollision(AnimatedEntity other)
{
var distance = Math.Abs(Vector2.Distance(this.CenterPosition, other.CenterPosition));
var inThisRadius = distance < this.Radius;
var inOtherRadius = distance < other.Radius;
if (inThisRadius || inOtherRadius)
{
return true;
}
else
{
return false;
}
}
/// <summary>
/// Handle collisions with other entities
/// </summary>
/// <param name="other">The entity that the bullet is colliding with.</param>
public override void Touch(AnimatedEntity other)
{
if (other is Asteroid)
{
var asteroid = other as Asteroid;
asteroid.Health = 0;
asteroid.Killer = this;
Kill();
}
else if (other is EnemyShip)
{
var enemyShip = other as EnemyShip;
enemyShip.Kill(this);
Kill();
}
base.Touch(other);
}