public int Points; // how many points the block awards when destroyed
#endregion Fields
#region Constructors
// class constructor. A block will not move, so I can set the edges at creation, assuming they will never move
public Block(PictureBox picture, Vector position, Vector size)
{
PictureBox = picture;
Position = position;
Size = size;
Edges[TopEdge] = new Ray(position, new Vector(Size.X, 0)); // top edge
Edges[RightEdge] = new Ray(Vector.Add(position, new Vector(Size.X, 0)), new Vector(0, Size.Y)); // right edge
Edges[BottomEdge] = new Ray(Vector.Add(position, new Vector(0, Size.Y)), new Vector(Size.X, 0)); // bottom edge
Edges[LeftEdge] = new Ray(position, new Vector(0, Size.Y)); // left edge
Game.Blocks.Add(this);
}
/// <summary>
/// calculates collisions between the ball and a paddle, and finds the paddle surface that was hit
/// </summary>
/// <param name="paddle">the paddle that is being hit</param>
/// <param name="newPosition">the position the ball has</param>
/// <param name="newVelocity">the velocity the ball is trying to move with</param>
/// <returns>the position, length and surface of the collision</returns>
public CollisionReturn CollidesWithPaddle(Paddle paddle, Vector newPosition, Vector newVelocity)
{
Ray[] Vectors = new Ray[4]; // vector rays of moving ball
Vectors[TopEdge] = new Ray(newPosition, newVelocity);
Vectors[RightEdge] = new Ray(Vector.Add(newPosition, new Vector(Size.X, 0)), newVelocity);
Vectors[BottomEdge] = new Ray(Vector.Add(newPosition, new Vector(0, Size.Y)), newVelocity);
Vectors[LeftEdge] = new Ray(Vector.Add(newPosition, new Vector(Size.X, Size.Y)), newVelocity);
CollisionReturn collisionReturn = new CollisionReturn(false);
foreach (Ray ray in Vectors)
{
int edgeID = 0;
foreach (Ray edge in paddle.Edges)
{
RaycastReturn raycastReturn = Ray.Raycast(ray, edge);
if (raycastReturn.Intersects)
{
if (collisionReturn.Intersects)
{
if (raycastReturn.length < collisionReturn.length)
{
collisionReturn = new CollisionReturn(raycastReturn);
collisionReturn.Edge = edgeID;
}
}
else
{
collisionReturn = new CollisionReturn(raycastReturn);
collisionReturn.Edge = edgeID;
}
}
edgeID++;
}
}
return collisionReturn;
}
/// <summary>
/// will check for collisions between 2 rays and return the results
/// </summary>
/// <param name="ray1">the first ray in the collision</param>
/// <param name="ray2">the second ray in the collision</param>
/// <returns>the position and length of the raycast collision</returns>
public static RaycastReturn Raycast(Ray ray1, Ray ray2)
{
// shorten the variable names
float x1 = ray1.Position.X;
float y1 = ray1.Position.Y;
float a1 = ray1.Direction.X;
float b1 = ray1.Direction.Y;
float x2 = ray2.Position.X;
float y2 = ray2.Position.Y;
float a2 = ray2.Direction.X;
float b2 = ray2.Direction.Y;
if (a1 * b2 == a2 * b1) // parallel, so won't collide
{
return new RaycastReturn(false); // rays don't collide, so return false collision
}
else // they collide at some point, given their lengths are infinite
{
float i = (x2 * b2 + a2 * y1 - a2 * y2 - x1 * b2) / (a1 * b2 - a2 * b1); // distance between start and collision along ray1
Vector position = new Vector(x1 + i * a1, y1 + i * b1); // form coordinates of collision
if (i > 1 || i < 0) // outside length of ray1
{
return new RaycastReturn(false); // do not meet each other, so return false collision
}
else // they collide within their lengths
{
float length = i * ray1.Length; // length of ray1 up to collision
return new RaycastReturn(true, position, length); // return true collision
}
}
}
/// <summary>
/// calculates collisions between the ball and a block, and finds the block surface tha was hit
/// </summary>
/// <param name="block">the block being hit</param>
/// <param name="newPosition">the position the ball has</param>
/// <param name="newVelocity">the velocity the ball is trying to move with</param>
/// <param name="collidedRays">a list of rayIDs which have already collided with a surface</param>
/// <returns>the position, length and surface of the collision</returns>
public CollisionReturn CollidesWithBlock(Block block, Vector newPosition, Vector newVelocity, List<int> collidedRays)
{
// vector rays of moving ball
Ray[] Vectors = new Ray[4];
Vectors[TopEdge] = new Ray(newPosition, newVelocity);
Vectors[RightEdge] = new Ray(Vector.Add(newPosition, new Vector(Size.X, 0)), newVelocity);
Vectors[BottomEdge] = new Ray(Vector.Add(newPosition, new Vector(0, Size.Y)), newVelocity);
Vectors[LeftEdge] = new Ray(Vector.Add(newPosition, new Vector(Size.X, Size.Y)), newVelocity);
CollisionReturn collisionReturn = new CollisionReturn(false);
int rayID = 0;
foreach (Ray ray in Vectors)
{
int edgeID = 0;
if (!collidedRays.Contains(rayID)) // if the ray being used hasn't already collided with a box
{
// check every edge of the block
foreach (Ray edge in block.Edges)
{
RaycastReturn raycastReturn = Ray.Raycast(ray, edge); // see if the ray meets the edge
if (raycastReturn.Intersects)
{
// if there has already been a collision, check for a shorter one
if (collisionReturn.Intersects)
{
if (raycastReturn.length < collisionReturn.length) // if the ball velocity ray hits this edge before any other ray hits an edge
{
collisionReturn = new CollisionReturn(raycastReturn);
collisionReturn.Edge = edgeID;
collisionReturn.Ray = rayID;
}
}
// haven't had a ray collision yet, so use this collision by default
else
{
collisionReturn = new CollisionReturn(raycastReturn);
collisionReturn.Edge = edgeID;
collisionReturn.Ray = rayID;
}
}
edgeID++; // check next edge
}
}
rayID++; // check next ray
}
return collisionReturn; // return results
}
/// <summary>
/// finds the rays for the edges at a specific moment
/// </summary>
private void CalculateEdges()
{
Vector position = Position;
Vector size = Size;
edges[TopEdge] = new Ray(position, new Vector(size.X, 0)); // top edge
edges[RightEdge] = new Ray(Vector.Add(position, new Vector(size.X, 0)), new Vector(0, size.Y)); // right edge
edges[BottomEdge] = new Ray(Vector.Add(position, new Vector(0, size.Y)), new Vector(size.X, 0)); // bottom edge
edges[LeftEdge] = new Ray(position, new Vector(0, size.Y)); // left edge
}
