Lights out - help needed

Unity Engine
,
1

I thought I’d just put this out there in case somebody has a quick answer (i.e a line or two of script) to my scenario.

I have a laser beam which has a point light attached to the end that hits things (hit.point)

This lights up the scenery around where the laser hits.

Problem:

The actual object that the laser hits (the ground, or a wall) doesn’t light up - because the light at the hit.point is exactly touching the object when it actually needs to stop a little short of the surface.

I figure I need to take the distance between the laser hit.point and the source of the laser and then move the light back towards the source a little, in order for the hit faces to be lit by the light.

Anyone with a snappy suggestion (even pointing me to the right page in the Unity manual) will save my brain some effort tonight when I eventually get the kids to bed and start up my Macbook after a long day in my boring day job.

Thanks.

2

Can’t you make the collider a little bigger?

3

Hmmmm… that might work but it would affect all collision detection in the level. Not sure I want my level scenery to have a collider that doesn’t quite fit. Still, I’m going to try that as it will only take a second :wink:

Looking into using Vector3.Distance right now.

4

Scaling the collider doesn’t work, because it’s complex geometry with normals pointing in all directions (some inwards, some out), and also several different objects.

So I think I need to get the distance the laser beam extends and then subtract a little and move the light at the end of each update…

5

You could also do a little vector math:

LaserStartPosition - HitPointPosition gives a Vector pointing from hitpoint to start. Normalize that vector to bring it to a length of 1 unit and add it to HitPointPosition. Set that as position of your light and it sits on the laser one unit before the hitpoint.

6

You can move the light back along the collision normal.

light.transform.position = collision.contacts[0].point + (collision.contacts[0].normal * movementFactor);

Where light is your light, collision is the Collision object you get from OnCollision(Enter/Exit/Stay), and movementFactor is some float that will determine how far back the light will move. If you’re raycasting replace “collision.contacts[0]” with your RaycastHit object.

7

Thanks for both those suggestions!

8

@B-joe, it works :slight_smile:

9

I meant making the laser’s collider bigger, but yeah, moving it back might be a better solution.

10

Glad I could help, but I think you should give the solution burnumd posted a try also. It takes fewer code and depending on the shape of your target and from where it’s hit it could also look more realistic.

11

thanks everyone,

I will try out everything to see what works best, time permitting :slight_smile:

The free version of my app was accepted for release by Apple yesterday, so I am full out on putting in the extra levels now for the full version!

12

Thanks Burnumd,

in the end I opted for your solution, modified for raycasting…

LaserLight.transform.position = Hit.point + Hit.normal*0.2;