How to Change Depth of Field: Focal Length from a Script (LWRP)?

Questions & Answers
1

I would like to change the focal length of a Depth of Field effect when I select an object in the game (using Unity 2019.2 with LWRP).

I’m thinking I would use Post Processing Volume as a game object, with the Depth of Field effect enabled.

The script would use:
using UnityEngine;
using UnityEngine.Rendering.PostProcessing;

Then I would create a variable of some type, and set it to hold the data of Post Processing Volume, but I cannot find the type in the Unity documents.

Then I would do something like:
myVar.focalLength = myNewValue;

I don’t know if focalLength is the proper name, because I can’t find that in Unity docs either.

Does anybody have a script for something like this?

2

It’s a catchy thing.
There could be more than one Volume blending at a time.

You need PostProcessLayer (it is should be in your Camera)

public PostProcessLayer  v2_PostProcess;

Then you should go through active Volumes:

            List<PostProcessVolume> volList = new List<PostProcessVolume>();
            PostProcessManager.instance.GetActiveVolumes(v2_PostProcess, volList, true, true);
            //
            foreach(PostProcessVolume vol in volList)
            {
                PostProcessProfile ppp = vol.profile;
                if (ppp) 
                {
                    DepthOfField dph;
                    if (ppp.TryGetSettings<DepthOfField>(out dph))
                    {
                        dph.focusDistance.value = REQUIRED_DISTANCE;
                    }
                }
            }

Focal distance should be changed.

3

Hey, thanks! This worked!

Here’s what I did:

  1. I have FirstPersonCharacter (which is the camera).
  2. I have a second game object that is the Post-process Volume (this comes in automatically when you start a new project in the LWRP template).
  3. I used the code you gave me in a script (see below.)
  4. I put the script onto the Post-process Volume.
  5. I dragged the camera object into the public V2_Post Process field in the inspector.

So, thank you very much!

As bonus work, once you’d set me on the path, I also searched through the two scripts DepthOfField.cs and DepthOfFieldComponent.cs and found the names of the other Depth of Field properties, so now I can also address those in that same script (see it below).

So, with this information I can now do things like, when the camera moves, apply a blur to the Camera, and when it stops set the focus length back to normal to clear up the picture. By the way, the name of my script / class is LERP_Focal_Length.cs, but there is no lerp function in it (yet). That’s the next objective, so hopefully nobody is confused by that name.

Script:
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Rendering.PostProcessing;

public class LERP_Focal_Length : MonoBehaviour
{

public int blur_amt = 1;
public PostProcessLayer v2_PostProcess;

// Start is called before the first frame update
void Start()
{
    

}

// Update is called once per frame
void Update()
{
    List<PostProcessVolume> volList = new List<PostProcessVolume>();
    PostProcessManager.instance.GetActiveVolumes(v2_PostProcess, volList, true, true);
    //
    foreach (PostProcessVolume vol in volList)
    {
        PostProcessProfile ppp = vol.profile;
        if (ppp)
        {
            DepthOfField dph;
            if (ppp.TryGetSettings<DepthOfField>(out dph))
            {
                //dph.focusDistance.value = 69;
                //dph.aperture.value = 30;
                dph.focalLength.value = blur_amt;
                //dph.kernelSize.value = KernelSize.VeryLarge;
            }
        }
    }
}

}