protected override bool CheckCollision(IDisplayableEntity entity1, IDisplayableEntity entity2)
{
// Get bounds of entity 1.
Rectangle entity1Bounds = new Rectangle
{
X = (int)entity1.Position.Value.X,
Y = (int)entity1.Position.Value.Y,
Height = entity1.Height,
Width = entity1.Width
};
// Get bounds of entity 2.
Rectangle entity2Bounds = new Rectangle
{
X = (int)entity2.Position.Value.X,
Y = (int)entity2.Position.Value.Y,
Height = entity2.Height,
Width = entity2.Width
};
// Check if the entity bounds intersect.
if (entity1Bounds.Intersects(entity2Bounds))
{
return(true);
}
return(false);
}
protected override bool CheckCollision(IDisplayableEntity entity1, IDisplayableEntity entity2)
{
// Calculate the radius of the entities.
float r1 = (entity1.Scale * entity1.Width) / 2;
float r2 = (entity2.Scale * entity2.Width) / 2;
// Check if the distance between the vectors is less than the radii.
if (Vector3.Distance(entity1.Position.Value, entity2.Position.Value) < (r1 + r2))
{
return(true);
}
return(false);
}
/// <summary>
/// Collision component update method.
/// </summary>
/// <param name="gameTime">Snapshot of elapsed time values.</param>
public void Update(GameTime gameTime)
{
// Get entities.
IReadOnlyList <IDisplayableEntity> entities = this.entities.Values.ToList();
// Run through entities and check if they collide.
// Condition to terminate is list size - 1, because the last entity will already have been
// checked with the other entities; this saves a wasteful iteration.
for (int i = 0; i < entities.Count - 1; i++)
{
// Get entity 1.
IDisplayableEntity entity1 = entities.ElementAt(i);
// Run through the other entities to check against.
// Here the loop count is i + 1, because we want to skip entities already checked and avoid checking
// against itself:
// i.e. entity index 0 is checked with index 3, when index 3 is being iterated in the main loop,
// setting it to i + 1 means it will start checking index 3 against index 4;
// this saves many wasteful iterations.
for (int j = i + 1; j < entities.Count; j++)
{
// Get entity 2.
IDisplayableEntity entity2 = entities.ElementAt(j);
// Check if entities collide.
if (CheckCollision(entity1, entity2))
{
// If entity is collidable, call on collide.
if (entity1 is ICollidable)
{
((ICollidable)entity1).OnCollide(entity2);
}
if (entity2 is ICollidable)
{
((ICollidable)entity2).OnCollide(entity1);
}
}
}
}
}
/// <summary> /// The method to use to check for collision between two entities. /// </summary> /// <param name="entity1"></param> /// <param name="entity2"></param> /// <returns>True if entities have collided, false otherwise.</returns> protected abstract bool CheckCollision(IDisplayableEntity entity1, IDisplayableEntity entity2);
