Question Collisions in high speed without unity physic / rigidbody

Hello everyone,

These days i experimented to works without unity physic / rigidbody in order to create a responsive 2D platformer, with importants velocities.
I use transform.Translate(velocity * Time.deltaTime) to apply my movements.

During my first test I managed collisions with :
- Raycasts (i fire 12 raycast, 3 by side, size 1by 1)
- If i collide (my player is inside a collider) i use transform.position to set the correct position of my player

For exemple, to detect the groud :

Code (CSharp):

1. Collider2D colMiddleSouth = FireRay(new Vector3(collider.bounds.min.x + halfWidthSprite, collider.bounds.min.y, 0), Vector3.down, 1);
2. Vector3 col_v3 = colMiddleSouth.bounds.max;
3. transform.position = new Vector3(transform.position.x, col_v3.y + halfHeightSprite, 0);

I was not satisfied because it becomes hard to manage complex collisions

So i did a second try, and i managed collisions with :
- Raycast, all the trick is to set the good length of the raycast according to player's velocity
- then if i collide at the length of my raycast i set velocity.x or .y to 0

For exemple :

Code (CSharp):

1.         float directionY = Mathf.Sign(velocity.y);
2.         rayLength = Mathf.Abs(velocity.y) * Time.deltaTime ;
3.  
4.         RaycastHit2D hit = Physics2D.Raycast(new Vector2(transform.position.x, transform.position.y-halfHeightSprite), Vector2.down, rayLength, collisionMask);
5.         Debug.DrawRay(new Vector2(transform.position.x, transform.position.y - 25), Vector2.down * rayLength, Color.red);
6.  
7.         if (hit)
8.         {
9.             velocity.y = 0;
10.         }

This time again i am not satisfied of the result.

Did you know others ways to manage collisions without rigidbody/unity physics?

 

Try spherecast or overlap sphere at your game objects position each frame it moves. Every fixed update I suppose.

https://docs.unity3d.com/ScriptReference/Physics.OverlapSphere.html

 

Yes i did come tests with overlap.
But my real problem here is how to manage pixel perfects collisions at high speed.
I wonder there are betters ways to manages collisions.

 

How high a speed are we talking max velocity? 4000?

because I notice raycast misses from certain angles even with draw ray on objects particular objects which are moving. Why don’t you see if it’s possible to for one frame only set your fixed update speed to be faster than your update speed, or your update speed to be switched off and to try and get two rapid collision checks in row before reverting update cycle.
So hopefully when the first check misses, the second check doesn’t.

The answer might be in time