Raycasting Question - [SOLVED]

[Tobias_Leif]

Hello!

Ive got a question regarding raycasting and if it is possible to only raycast towards one object?

I made a simple picture to show how things are lined up:

Or in unity:

So they are using the layermask correctly to see the enemies , but when 1 wants to attack 4 - then 1 thinks that there is no Line of sight becouse the Raycast is intercepted by 3.

Code:

    public virtual bool CheckLOS(Unit ThisUnit , Unit Enemy)
    {
        RaycastHit hit;
        Vector3 dir = Enemy.transform.position - ThisUnit.transform.position;
        int layer = 0;
        if (ThisUnit.Team == 21) { layer = 22; }
        if (ThisUnit.Team == 22) { layer = 21; }
        int layermask = 1 << layer;
        int walllayer = 10;
        int walllayermask = 1 << walllayer;
        int finallayer = layermask | walllayermask;

        if (Physics.Raycast(ThisUnit.transform.position, dir, out hit, 5f, finallayer))
        {
            if(hit.collider.transform==Enemy.transform)
            {
                return true;
            }
        }
            return false;
    }

Is there any way to check line of sight that ignores all colliders/layers besides the target.

-Tobias

[Kurt-Dekker]

There’s a lot of flavors of raycast… you can actually raycast directly against a specific collider, which ignores everything else.

Raycasting, colliders, planes, Plane, etc:

(Help)How can i detect how many raycasts are hitting an object?

There are many types of 3D raycasts. One is the generic Physics one: hits anything in the scene Another is one that lives on a collider. If you know which collider you care about, you can use that collider instance to see if a ray hits it. That way you not only know that it hit, but because you are already asking "Did anything hit this collider?" you also know what collider it is. These are some of the types of 3D raycasts: https://docs.unity3d.com/ScriptReference/Physics.Raycast.htm…

Keeping a plain/terrain within the view frustrum

You can get rays from the camera at a given spot, so one approach is to cast rays from the camera corners and make sure they hit your terrain, or hit your terrain bounding box. To ignore screen pixel dimensions and just get the corner rays, this is the API you want: The nice part is that it doesn’t matter how your camera is set, how your field of view is set, etc., It just works. You can use this to raycast and hit physics on your ground using: asks “did I hit any collider in the scene?…

And there is also EventSystem.RaycastAll for raycasting in the UI / EventSystems context.

Raycasting in 2D:

Randomly placing objects near polygon collider 2D

Epoch! I always love your posts because you’re always working on the next thing. Awesome. So for this I would pick a random spot from left to right at the top of your screen, then raycast down to “hit” the terrain and see how high it is at that point, and from that you can emplace your missile above the ground, or on a pedestal or whatever. Remember there are various flavors of Raycast in Physics2D: https://docs.unity3d.com/ScriptReference/Physics2D.Raycast.html “Tell me if I hit any 2D col…

[Tobias_Leif]

Hey Kurt , thanks for replying so fast.

The collider.raycast seems to be what i am looking for , but it seems that this causes the units to see through layer 10 (Walls) - and is always treated as being in line of sight.

[Kurt-Dekker]

Might need a few raycasts…

First do a regular old raycast in the direction of the guy you want, but set layers to only pick up WALLS.

For this first raycast you are only looking to find a point where you hit a wall.

From this point you can compute the distance of how far your ray can go before it hits a wall.

Now raycast at the target you want:

• is the impact point farther than the first raycast distance? Then you can’t hit it.

• if the impact point is closer, then yeah, you can hit it.

[Tobias_Leif]

Hey Kurt , that seems to have done the trick thanks alot!

Cant believe i didnt think about using several raycasts - sometimes you really need another pair of eyes on the code.

The code that worked for anyone else that has this problem in the future:

    public virtual bool CheckLOS(Unit ThisUnit , Unit Enemy)
    {
        RaycastHit hit;
        Vector3 dir = Enemy.transform.position - ThisUnit.transform.position;
        int walllayer = 10;
        int walllayermask = 1 << walllayer;

        float dist=Vector3.Distance(ThisUnit.transform.position, Enemy.transform.position);

        if (Physics.Raycast(ThisUnit.transform.position, dir, out hit, dist, walllayermask))
        {
           return false;
        }
        else
        {
            Ray ray = new Ray(ThisUnit.transform.position, dir);
            if (Enemy.collider.Raycast(ray, out hit, 5f))
            {
                return true;
            }
        }

        return false;
    }

[Kurt-Dekker]

@Tobias_Leif

that seems to have done the trick thanks alot!

Awesome… you’re welcome!!

Doing multiple raycasts is actually pretty common, and Unity is a beast: raycasts are computationally fairly cheap, at least in most physics setups.

For instance, one application is to tell what percent of a given target is obscured, such as for “cover and concealment” kinda games like XCOM.

You can accomplish this by raycasting to multiple points on the target: head, chest, arms, legs, etc. Or you could even just raycast to X points from top to bottom of the target, or even left / right in a box around the player.

If you can hit them with 100% of the raycasts then you know they are not in cover.

In my Jetpack Kurt Space Flight game I even do them stochastically (randomly) to detect small objects beneath your craft to warn you about uneven ground: every frame I raycast three different random rays for 1 meter below the ship, and if any one of them differs in length from the others by more than 0.25m then I consider it uneven ground and activate a beeping warning system. I can even detect tiny little posts like landing lights within a few moments of them coming underneath your ship.

https://www.youtube.com/watch?v=34wbtTIWdDQ

[Tobias_Leif]

That is a great thing to learn. I was handling raycasts like Getcomponents and distance calculations.
After i get this up and running i will have to run through my code again and see if i can improve/switch to the other raycast types.

Thanks again. Ive got work ahead of me after this