private static CollidingSide IsColliding(Level level, IPhysicsObject obj, ref Point posDelta, ref int xHeightDelta)
{
Rectangle newRectX = new Rectangle(obj.BoundingRect.Location + new Point(posDelta.X, 0), obj.BoundingRect.Size);
Rectangle newRectY = new Rectangle(obj.BoundingRect.Location + new Point(0, posDelta.Y), obj.BoundingRect.Size);
Rectangle groundedRect = new Rectangle(obj.BoundingRect.Location + new Point(0, 1), obj.BoundingRect.Size);
CollidingSide result = CollidingSide.NONE;
obj.IsGrounded = false;
foreach (ICollider collider in level.Colliders)
{
if (collider.IsColliding(newRectY))
{
result |= posDelta.Y > 0 ? CollidingSide.BOTTOM : CollidingSide.TOP;
}
if (collider.IsColliding(newRectX))
{
CollidingSide tmpResult = posDelta.X > 0 ? CollidingSide.RIGHT : CollidingSide.LEFT;
// try moving upwards until we don't collide anymore for 4 steps, so that player can walk up slopes
for (int i = 0; i < 4; i++)
{
newRectX = new Rectangle(obj.BoundingRect.Location + new Point(posDelta.X, -i), obj.BoundingRect.Size);
if (!collider.IsColliding(newRectX))
{
xHeightDelta = i;
tmpResult &= ~CollidingSide.LEFT;
tmpResult &= ~CollidingSide.RIGHT;
tmpResult |= CollidingSide.SLOPE;
break;
}
}
result |= tmpResult;
}
if (collider.IsColliding(groundedRect))
{
obj.IsGrounded = true;
}
}
return(result);
}
private static void DoObjectPhysicsUpdate(Level level, IPhysicsObject obj, GameTime gameTime)
{
if (IsGravityEnabled)
{
obj.Velocity -= new Vector2(
(obj.Acceleration.X == 0) ? Math.Sign(obj.Velocity.X) * obj.Drag : 0,
0
);
}
else
{
obj.Velocity -= new Vector2(
(obj.Acceleration.X == 0) ? Math.Sign(obj.Velocity.X) * obj.Drag : 0,
(obj.Acceleration.Y == 0) ? Math.Sign(obj.Velocity.Y) * obj.Drag : 0
);
}
// apply acceleration and gravity if activated
obj.Velocity += new Vector2(obj.Acceleration.X, obj.Acceleration.Y + (IsGravityEnabled ? (float)(700 * gameTime.ElapsedGameTime.TotalSeconds + 0.01) : 0));
// the new position of the object after it has been moved by its velocity
Point posDelta = (obj.Velocity * (float)gameTime.ElapsedGameTime.TotalSeconds).ToPoint();
int xHeightDelta = 0;
// apply velocity if object is not colliding with anything
CollidingSide collidingSide = IsColliding(level, obj, ref posDelta, ref xHeightDelta);
obj.Velocity = new Vector2(
(!collidingSide.HasFlag(CollidingSide.LEFT) && !collidingSide.HasFlag(CollidingSide.RIGHT)) ? obj.Velocity.X : 0,
(!collidingSide.HasFlag(CollidingSide.BOTTOM) && !collidingSide.HasFlag(CollidingSide.TOP)) ? obj.Velocity.Y : 0
);
obj.Position += new Vector2(
(!collidingSide.HasFlag(CollidingSide.LEFT) && !collidingSide.HasFlag(CollidingSide.RIGHT)) ? posDelta.X : 0,
(!collidingSide.HasFlag(CollidingSide.BOTTOM) && !collidingSide.HasFlag(CollidingSide.TOP)) ? posDelta.Y :
(collidingSide.HasFlag(CollidingSide.SLOPE) &&
!collidingSide.HasFlag(CollidingSide.LEFT) &&
!collidingSide.HasFlag(CollidingSide.RIGHT) ? -xHeightDelta : 0)
);
}
