/// <summary>
/// Calculates the collision vector between 2 CollisionObjects as seen from refObj, given a certain collision direction.
/// </summary>
/// <param name="refObj">The object which collides with the other.</param>
/// <param name="collObj">The object with which the first collides.</param>
/// <param name="collisionDir">The directionality of the collision.</param>
/// <returns>A vector representing the normal force collObj enacts on refObj.</returns>
public static Vector2 CollisionForce(CollisionObject refObj, CollisionObject collObj, Vector2 collisionDir)
{
#region creation variables
Vector2 collisionVector = Vector2.Zero;
Rectangle refBox = refObj.GetCollisionBox();
Rectangle collBox = collObj.GetCollisionBox();
float smallestWidth;
float smallestHeight;
if (refBox.Width < collBox.Width)
{
smallestWidth = refBox.Width;
}
else
{
smallestWidth = collBox.Width;
}
if (refBox.Height < collBox.Height)
{
smallestHeight = refBox.Height;
}
else
{
smallestHeight = collBox.Height;
}
#endregion
#region collision
switch (collisionDir.ToString())
{
#region vertical
case "{X:0 Y:-1}":
if (refObj.GetSpeedTotal().Y > 0)
{
collisionVector.Y -= refObj.GetSpeedTotal().Y *(1 + (collObj.GetBounciness() / 10) + Math.Abs(refBox.Bottom - collBox.Top) / smallestHeight);
}
break;
case "{X:0 Y:1}":
if (refObj.GetSpeedTotal().Y < 0)
{
collisionVector.Y -= refObj.GetSpeedTotal().Y *(1 + (collObj.GetBounciness() / 10) + Math.Abs(collBox.Bottom - refBox.Top) / smallestHeight);
}
break;
#endregion
#region horizontal
case "{X:-1 Y:0}":
if (refObj.GetSpeedTotal().X > 0 && (refBox.Center.Y + (refBox.Height * 0.9f) / 2 > collBox.Top || refBox.Center.Y - (refBox.Height * 0.9f) / 2 < collBox.Bottom))
{
collisionVector.X -= refObj.GetSpeedTotal().X *(1 + (collObj.GetBounciness() / 10) + Math.Abs(collBox.Left - refBox.Right) / (smallestWidth));
}
if (Globals.input.ActionsPressed().Contains(Input.Action.Right))
{
collisionVector.X -= 0.1f;
}
break;
case "{X:1 Y:0}":
if (refObj.GetSpeedTotal().X < 0 && (refBox.Center.Y + (refBox.Height * 0.9f) / 2 > collBox.Top || refBox.Center.Y - (refBox.Height * 0.9f) / 2 < collBox.Bottom))
{
collisionVector.X -= refObj.GetSpeedTotal().X *(1 + (collObj.GetBounciness() / 10) + Math.Abs(refBox.Left - collBox.Right) / (smallestWidth));
}
if (Globals.input.ActionsPressed().Contains(Input.Action.Left))
{
collisionVector.X += 0.1f;
}
break;
#endregion
#region diagonal
case "{X:-1 Y:-1}":
case "{X:-1 Y:1}":
case "{X:1 Y:-1}":
case "{X:1 Y:1}":
Vector2 center = new Vector2(collBox.Center.X, collBox.Center.Y);
collisionVector += DiagonalCollision(refObj, new Circle(center, Vector2.Distance(center, new Vector2(collBox.X, collBox.Y)))) * PhysicsConstants.metersPerPixel;
break;
#endregion
}
if (Math.Sign(collObj.GetSpeedTotal().X) != Math.Sign(refObj.GetSpeedTotal().X))
{
collisionVector += collObj.GetSpeed() * refObj.CollisionImpactMultiplier();
}
#endregion
return(collisionVector);
}
/// <summary>
/// Determines the drag vector on a CollisionObject.
/// </summary>
/// <param name="obj">The CollisionObject.</param>
/// <returns>A vector representing the drag-force.</returns>
public static Vector2 DragVector(CollisionObject obj)
{
float dragY = -0.5f * PhysicsConstants.airDensity * PhysicsConstants.dragCoeff * (float)Math.Pow(obj.GetCollisionBox().Width *PhysicsConstants.metersPerPixel, 2) * (float)Math.Pow(obj.GetSpeed().Y, 3) / Math.Abs(obj.GetSpeed().Y);
float dragX = -0.5f * PhysicsConstants.airDensity * PhysicsConstants.dragCoeff * (float)Math.Pow(obj.GetCollisionBox().Height *PhysicsConstants.metersPerPixel, 2) * (float)Math.Pow(obj.GetSpeed().X, 3) / Math.Abs(obj.GetSpeed().X);
#region check for NaN
if (float.IsNaN(dragY))
{
dragY = 0;
}
if (float.IsNaN(dragX))
{
dragX = 0;
}
#endregion
return(new Vector2(dragX / obj.GetMass(), dragY / obj.GetMass()) * (float)Globals.deltaTime.TotalSeconds * PhysicsConstants.metersPerPixel);
}
