2DPlatformController_phys.cs

//Allocate space for our hits outside the function so that
//garbage collection doesnt have to repeatedly collect our hits
RaycastHit2D[] hits = new RaycastHit2D[1];

/// <summary>
/// Move in the specified direction, modifying velocity if we hit something
/// </summary>
/// <param name="velocity">Current veloctity</param>
/// <param name="remainingDelta">Movement to do in this frame</param>
/// <param name="newVelocity">Output new velocity</param>
/// <param name="newRemaining">Remaining movement this frame after moving</param>
/// <param name="hit">Output hit</param>
/// <param name="normalBias">How much should we adjust the final position by the normal direction of the hit</param>
/// <returns>true if we need to cast again, false otherwise.</returns>
bool CastAndMove(Vector2 velocity, Vector2 remainingDelta, out Vector2 newVelocity, out Vector2 newRemaining, out RaycastHit2D hit, float normalBias = 0.05f) {
    //save initial position
    Vector3 opos = rigidbody.position = transform.position;
    
    //Collider cast 
    int hitCount = collider.Cast(remainingDelta, terrainFilter, hits, remainingDelta.magnitude);
    hit = hits[0];
    
    //If we didnt hit, just move
    if (!hit) {
        transform.Translate(remainingDelta);
        newRemaining = Vector3.zero;
        newVelocity = velocity;
        return false;
    }
    //We did hit
    else {
        //Move the character
        transform.position = hit.centroid + normalBias * hit.normal;
        //Remove moved vel from remaining
        newRemaining = remainingDelta + (Vector2)(opos - transform.position);
        newVelocity = velocity - (Vector2.Dot(velocity, hit.normal) * hit.normal);
        //Make remaining velocity change when hitting something
        newRemaining = newRemaining - Vector2.Dot(newRemaining, hit.normal) * hit.normal;
        return true;
    }
}