//Note: This code is inspired by:
//URL: https://gamedevelopment.tutsplus.com/tutorials/how-to-create-a-custom-2d-physics-engine-the-basics-and-impulse-resolution--gamedev-6331
//SAT Collision response is good, you will possess the vector to push the two objects from each other
void Collider2D.CollisionResponse(Rigidbody2D YourRigidBody, Collider2D collider, float DeltaTime, ref List <GameObjectComponent> CDs, Vector2 CollisionPos, bool ResetVelocity)
{
if (collider is CircleCollider)
{
Rectangle ThisCollider = GetDynamicCollider();
CircleCollider IncomingCollider = collider as CircleCollider;
/////////////////////////This code is heavily inspired by "OneLoneCoder" the youtuber///////////////////////
gameObject.Transform.Position = CollisionPos;
// Statically resolve the collision
gameObject.Transform.Position -= Vector2.Normalize(vRayToNearest) * fOverlap;
if (IncomingCollider.gameObject.Transform.Position.Y + IncomingCollider.Center.Y > ThisCollider.Top && IncomingCollider.gameObject.Transform.Position.Y + IncomingCollider.Center.Y < ThisCollider.Bottom)
{
YourRigidBody.Velocity.X = 0;
}
if (IncomingCollider.gameObject.Transform.Position.X + IncomingCollider.Center.X > ThisCollider.Left && IncomingCollider.gameObject.Transform.Position.X + IncomingCollider.Center.X < ThisCollider.Right)
{
YourRigidBody.Velocity.Y = 0;
}
}
else
{
Rectangle DC1 = GetDynamicCollider();
Rectangle DC2 = (collider as BoxCollider2D).GetDynamicCollider();
float DistanceBetweenCollidersX = YourRigidBody.Velocity.X > 0 ? Math.Abs(DC1.Right - DC2.Left) : Math.Abs(DC1.Left - DC2.Right);
float DistanceBetweenCollidersY = YourRigidBody.Velocity.Y > 0 ? Math.Abs(DC1.Bottom - DC2.Top) : Math.Abs(DC1.Top - DC2.Bottom);
float TimeBetweenCollidersX = YourRigidBody.Velocity.X != 0 ? Math.Abs(DistanceBetweenCollidersX / YourRigidBody.Velocity.X) : 0;
float TimeBetweenCollidersY = YourRigidBody.Velocity.Y != 0 ? Math.Abs(DistanceBetweenCollidersY / YourRigidBody.Velocity.Y) : 0;
float ShortestTime;
var OldPos = YourRigidBody.gameObject.Transform.Position;
if (YourRigidBody.Velocity.X != 0 && YourRigidBody.Velocity.Y == 0)
{
// Colliison on X-axis only
ShortestTime = TimeBetweenCollidersX;
YourRigidBody.gameObject.Transform.MoveX(ShortestTime * YourRigidBody.Velocity.X);
YourRigidBody.Velocity.X = ResetVelocity ? 0 : YourRigidBody.Velocity.X;
}
else if (YourRigidBody.Velocity.X == 0 && YourRigidBody.Velocity.Y != 0)
{
// Colliison on Y-axis only
ShortestTime = TimeBetweenCollidersY;
YourRigidBody.gameObject.Transform.MoveY(ShortestTime * YourRigidBody.Velocity.Y);
YourRigidBody.Velocity.Y = ResetVelocity ? 0 : YourRigidBody.Velocity.Y;
}
else
{
// Colliison on both axis
ShortestTime = Math.Min(TimeBetweenCollidersX, TimeBetweenCollidersY);
YourRigidBody.gameObject.Transform.Move(ShortestTime * YourRigidBody.Velocity.X, ShortestTime * YourRigidBody.Velocity.Y);
//YourRigidBody.Velocity = ResetVelocity? Vector2.Zero : YourRigidBody.Velocity;
if (SlideCollision)
{
if (ShortestTime == TimeBetweenCollidersX)
{
YourRigidBody.gameObject.Transform.Position.X = OldPos.X;
YourRigidBody.Velocity.X = ResetVelocity ? 0 : YourRigidBody.Velocity.X;
if (!collider.CollisionDetection(this, false))
{
YourRigidBody.gameObject.Transform.Position.Y = CollisionPos.Y;
}
}
if (ShortestTime == TimeBetweenCollidersY)
{
YourRigidBody.gameObject.Transform.Position.Y = OldPos.Y;
YourRigidBody.Velocity.Y = ResetVelocity ? 0 : YourRigidBody.Velocity.Y;
if (!collider.CollisionDetection(this, false))
{
YourRigidBody.gameObject.Transform.Position.X = CollisionPos.X;
}
}
}
else
{
YourRigidBody.Velocity = ResetVelocity ? Vector2.Zero : YourRigidBody.Velocity;
}
}
foreach (Collider2D CD in CDs)
{
if (!gameObject.Name.Equals((CD as GameObjectComponent).gameObject.Name) && !CD.IsTrigger() && CD.CollisionDetection(this, false))
{
YourRigidBody.gameObject.Transform.Position = OldPos;
YourRigidBody.Velocity = Vector2.Zero;
break;
}
}
}
}
