public CollisionContact(CollisionContact contact)
: this(contact.A, contact.B, contact.Normal, contact.Distance)
{
}
private bool IsInternalEdge(CollisionContact contact)
{
return false;
}
private bool CalculateCollisionCorrection(GameTime gameTime, ref CollisionContact contact)
{
//Non-stationary object
ICutlassCollidable first = contact.A;
//Stationary object
ICutlassCollidable second = contact.B;
Vector2 halfExtents = new Vector2(second.CurrentFrameBoundingRect.Width / 2, second.CurrentFrameBoundingRect.Height / 2);
BoundingRectangle firstPlusHalfExtents = new BoundingRectangle(first.CurrentFrameBoundingRect.Left - halfExtents.X,
first.CurrentFrameBoundingRect.Top - halfExtents.Y,
first.CurrentFrameBoundingRect.Width + 2 * halfExtents.X,
first.CurrentFrameBoundingRect.Height + 2 * halfExtents.Y);
//Get closest point
Vector2 closestPoint = second.CurrentFrameBoundingRect.Center;
//X Axis
float x = second.CurrentFrameBoundingRect.Center.X;
if (x < firstPlusHalfExtents.Left) x = firstPlusHalfExtents.Left;
if (x > firstPlusHalfExtents.Right) x = firstPlusHalfExtents.Right;
closestPoint.X = x;
//Y Axis
float y = second.CurrentFrameBoundingRect.Center.Y;
if (y < firstPlusHalfExtents.Top) y = firstPlusHalfExtents.Top;
if (y > firstPlusHalfExtents.Bottom) y = firstPlusHalfExtents.Bottom;
closestPoint.Y = y;
//Check if second's center is inside fisrtPlusHalfExtents. If so, find closest edge for negative distance.
if (closestPoint == second.CurrentFrameBoundingRect.Center)
{
Vector2 distanceToClosestEdge;
//X Axis
if (Math.Abs(closestPoint.X - firstPlusHalfExtents.Right) > Math.Abs(closestPoint.X - firstPlusHalfExtents.Left))
distanceToClosestEdge.X = closestPoint.X - firstPlusHalfExtents.Left;
else
distanceToClosestEdge.X = closestPoint.X - firstPlusHalfExtents.Right;
//Y Axis
if (Math.Abs(closestPoint.Y - firstPlusHalfExtents.Bottom) > Math.Abs(closestPoint.Y - firstPlusHalfExtents.Top))
distanceToClosestEdge.Y = closestPoint.Y - firstPlusHalfExtents.Top;
else
distanceToClosestEdge.Y = closestPoint.Y - firstPlusHalfExtents.Bottom;
//Minimum
Vector2 axisMinor = VectorUtilities.MinorAxis(distanceToClosestEdge);
closestPoint = closestPoint + axisMinor;
}
//Calculate distance and Normal
Vector2 distance = closestPoint - second.CurrentFrameBoundingRect.Center;
contact.Distance = VectorUtilities.MaximumComponent(distance);
if (contact.Distance == 0.0f)//right up against each other, will get invalid normal.
{
//On Top
if (first.CurrentFrameBoundingRect.Bottom == second.CurrentFrameBoundingRect.Top)
{
contact.Normal = new Vector2(0.0f, -1.0f);
if ((first.Side & CollisionSide.Bottom) == 0 ||
(second.Side & CollisionSide.Top) == 0)
return false;
}
//To the Right
else if (first.CurrentFrameBoundingRect.Left == second.CurrentFrameBoundingRect.Right)
{
contact.Normal = new Vector2(1.0f, 0.0f);
if ((first.Side & CollisionSide.Left) == 0 ||
(second.Side & CollisionSide.Right) == 0)
return false;
}
//On Bottom
else if (first.CurrentFrameBoundingRect.Top == second.CurrentFrameBoundingRect.Bottom)
{
contact.Normal = new Vector2(0.0f, 1.0f);
if ((first.Side & CollisionSide.Top) == 0 ||
(second.Side & CollisionSide.Bottom) == 0)
return false;
}
//To the Left
else if (first.CurrentFrameBoundingRect.Right == second.CurrentFrameBoundingRect.Left)
{
contact.Normal = new Vector2(-1.0f, 0.0f);
if ((first.Side & CollisionSide.Right) == 0 ||
(second.Side & CollisionSide.Left) == 0)
return false;
}
}
else
{
contact.Normal = VectorUtilities.NormalizedMajorAxis(distance);
}
//On top
if (contact.Normal.Y == -1.0f &&
((first.Side & CollisionSide.Bottom) == 0 ||
(second.Side & CollisionSide.Top) == 0))
{
return false;
}
//To the Right
else if (contact.Normal.X == 1.0f &&
((first.Side & CollisionSide.Left) == 0 ||
(second.Side & CollisionSide.Right) == 0))
{
return false;
}
//On Bottom
else if (contact.Normal.Y == 1.0f &&
((first.Side & CollisionSide.Top) == 0 ||
(second.Side & CollisionSide.Bottom) == 0))
{
return false;
}
//To the Left
else if (contact.Normal.X == -1.0f &&
((first.Side & CollisionSide.Right) == 0 ||
(second.Side & CollisionSide.Left) == 0))
{
return false;
}
Boolean returnValue = false;
//Collision Direction is X
if (Math.Abs(contact.Normal.X) >= Math.Abs(contact.Normal.Y) &&
(((first.Velocity.X * gameTime.ElapsedGameTime.TotalMilliseconds) + contact.Distance) * contact.Normal.X < 0))
returnValue = true;
//Collision Direction is Y
if (Math.Abs(contact.Normal.X) <= Math.Abs(contact.Normal.Y) &&
(((first.Velocity.Y * gameTime.ElapsedGameTime.TotalMilliseconds) + contact.Distance) * contact.Normal.Y < 0))
returnValue = true;
return returnValue;
}
private void CheckCollisionsInGroup(GameTime gameTime, List<ICutlassCollidable> collidableObjects)
{
if (collidableObjects == null || collidableObjects.Count <= 1)
return;
for (int i = 0; i < collidableObjects.Count; i++)
{
ICutlassCollidable first = collidableObjects[i];
for (int j = i + 1; j < collidableObjects.Count; j++)
{
ICutlassCollidable second = collidableObjects[j];
bool collisionCategoriesOverlap = CheckCollisionCategories(first, second);
//If both are stationary, or neither is stationary, detect collision but don't do anything about it.
if (first.Stationary == second.Stationary)
{
if (collisionCategoriesOverlap && first.NextFrameBoundingRect.Intersects(second.NextFrameBoundingRect))
{
first.CollisionDetected(second);
second.CollisionDetected(first);
}
}
//If only one is stationary, detect collision and correct non-stationary object
else
{
//contact.A is non-stationary object.
CollisionContact collisionContact;
if (first.Stationary)
collisionContact = new CollisionContact() { A = second, B = first };
else
collisionContact = new CollisionContact() { A = first, B = second };
if (collisionCategoriesOverlap && CalculateCollisionCorrection(gameTime, ref collisionContact) && !IsInternalEdge(collisionContact))
{
collisionContact.A.CollisionDetectedWithCorrection(collisionContact.B, collisionContact.Normal, collisionContact.Distance);
collisionContact.B.CollisionDetected(collisionContact.A);
}
}
}
}
}
public CollisionContact(CollisionContact contact)
: this(contact.A, contact.B, contact.Normal, contact.Distance)
{
}