Fix lipsync not starting when renderer changes

[nixxquality]

Summary

This pull request adds a Change attribute to the Renderer property on the Voice transmitter component.
The executed method will enable lipsync if the Renderer is valid.

Motivation & Context

Fixes: #201

Implementation Details

I had to make the Change method public, or it wouldn't be found:

This matches the usage in Dresser:

sbox-public/engine/Sandbox.Engine/Scene/Components/Game/Dresser.cs

Line 284 in 91fa40b

public void OnManualChange( float a, float b )

The contents of the Change method are taken from the OnInternalEnabled function:

sbox-public/engine/Sandbox.Engine/Scene/Components/Audio/VoiceComponent.cs

Lines 155 to 158 in 91fa40b

	if ( Renderer.IsValid() && Renderer.Model.MorphCount > 0 )
	{
	morphs = new float[Renderer.Model.MorphCount];
	}

With just that code, the lip sync would only work when you stopped talking and then started talking again, so I looked at this as well:

sbox-public/engine/Sandbox.Engine/Scene/Components/Audio/VoiceComponent.cs

Lines 402 to 426 in 91fa40b

	private unsafe void OnVoice( byte[] buffer )
	{
	if ( buffer.Length < 2 )
	return;
	if ( soundStream is null )
	return;
	VoiceManager.Uncompress( buffer, samples =>
	{
	if ( !sound.IsValid() )
	{
	sound = soundStream.Play();
	sound.TargetMixer = TargetMixer;
	sound.Distance = Distance;
	sound.Falloff = Falloff;
	sound.LipSync.Enabled = LipSync && Renderer.IsValid();
	sound.IsVoice = true;
	}
	soundStream.WriteData( samples.Span );
	LastPlayed = 0;
	UpdateSound();
	} );
	}

(emphasis on line 417)

The current code seems to work in both instances. Feel free to test it with the sample project in the linked issue.

Checklist

• Code follows existing style and conventions
• No unnecessary formatting or unrelated changes
• Public APIs are documented (if applicable)
• Unit tests added where applicable and all passing
• I’m okay with this PR being rejected or requested to change 🙂

[nixxquality]

badandbest pointed out in the Discord that the public keyword was required because of TypeLibrary restrictions.

I'm keeping it public to match Dresser's implementation for now, but if you'd like I can change it to be private with [Expose] instead.

[Copilot]

Pull request overview

This pull request fixes an issue where lip sync does not start when the Renderer property is set on a Voice component after initialization. The fix adds a Change attribute to the Renderer property that triggers initialization logic when the renderer is updated at runtime.

Changes:

• Added a Change attribute to the Renderer property to trigger a callback when the renderer is changed
• Implemented the OnRendererChange public method to handle renderer changes by initializing the morphs array and enabling/disabling lip sync appropriately

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[nixxquality]

One thing I forgot to mention: Perhaps the same code should also run when LipSync is changed between true and false?

If you'd like, I'll add another Change method which would do the same thing.

[handsomematt]

Why [Change] over a standard C# property setter?

[nixxquality]

Why [Change] over a standard C# property setter?

This is just my opinion, but I believe setters should be used for verification of inputs while side effects as a result of the value changing should be elsewhere. I really like the Change attribute because it fills that gap.
My way of verifying this was to check if Change was even used in the s&box code base at all, and that's where I saw the use in Dresser.

If you're saying that a setter would be following existing conventions, I could do that instead.

[lolleko]

Also in favor of using a regular setter.
Change and MakeDirty obfuscate the code. I hate that we have them.

[nixxquality]

Understood. I'm gonna look into that possible NRE as well.

[nixxquality]

I went ahead and fixed the possible NRE in the constructor as well since that's where I took that piece of code from.
Here's a GameObject which triggers the NRE in current master on start:

[
  {
    "__guid": "81fafe3f-e2b5-4947-84f6-fa251cc22677",
    "__version": 2,
    "Flags": 0,
    "Name": "Object",
    "Position": "130.7224,13.61734,39.1015",
    "Rotation": "0,0,0,1",
    "Scale": "1,1,1",
    "Tags": "",
    "Enabled": true,
    "NetworkMode": 2,
    "NetworkFlags": 0,
    "NetworkOrphaned": 0,
    "NetworkTransmit": true,
    "OwnerTransfer": 1,
    "Components": [
      {
        "__type": "Sandbox.SkinnedModelRenderer",
        "__guid": "5eedc285-87d1-4436-9660-d99fc34932f8",
        "__enabled": true,
        "Flags": 0,
        "AnimationGraph": null,
        "BodyGroups": 18446744073709551615,
        "BoneMergeTarget": null,
        "CreateAttachments": false,
        "CreateBoneObjects": false,
        "LodOverride": null,
        "MaterialGroup": null,
        "MaterialOverride": null,
        "Materials": null,
        "Model": null,
        "Morphs": {},
        "OnComponentDestroy": null,
        "OnComponentDisabled": null,
        "OnComponentEnabled": null,
        "OnComponentFixedUpdate": null,
        "OnComponentStart": null,
        "OnComponentUpdate": null,
        "Parameters": {
          "bools": {},
          "ints": {},
          "floats": {},
          "vectors": {},
          "rotations": {}
        },
        "PlaybackRate": 1,
        "RenderOptions": {
          "GameLayer": true,
          "OverlayLayer": false,
          "BloomLayer": false,
          "AfterUILayer": false
        },
        "RenderType": "On",
        "Sequence": {
          "Name": null,
          "Looping": true,
          "Blending": false
        },
        "Tint": "1,1,1,1",
        "UseAnimGraph": true
      },
      {
        "__type": "Sandbox.Voice",
        "__guid": "98497791-71ab-49c8-af88-88b20934183c",
        "__enabled": true,
        "Flags": 0,
        "Distance": 15000,
        "Falloff": [
          {
            "x": 0,
            "y": 1,
            "in": 0,
            "out": -1.8,
            "mode": "Mirrored"
          },
          {
            "x": 0.05,
            "y": 0.22,
            "in": 3.5,
            "out": -3.5,
            "mode": "Mirrored"
          },
          {
            "x": 0.2,
            "y": 0.04,
            "in": 0.16,
            "out": -0.16,
            "mode": "Mirrored"
          },
          {
            "x": 1,
            "y": 0,
            "in": 0,
            "out": 0,
            "mode": "Mirrored"
          }
        ],
        "LipSync": true,
        "Loopback": false,
        "Mode": "AlwaysOn",
        "MorphScale": 3,
        "MorphSmoothTime": 0.1,
        "OnComponentDestroy": null,
        "OnComponentDisabled": null,
        "OnComponentEnabled": null,
        "OnComponentFixedUpdate": null,
        "OnComponentStart": null,
        "OnComponentUpdate": null,
        "PushToTalkInput": "voice",
        "Renderer": {
          "_type": "component",
          "component_id": "5eedc285-87d1-4436-9660-d99fc34932f8",
          "go": "81fafe3f-e2b5-4947-84f6-fa251cc22677",
          "component_type": "SkinnedModelRenderer"
        },
        "VoiceMixer": {
          "Name": "unknown",
          "Id": "00000000-0000-0000-0000-000000000000"
        },
        "Volume": 1,
        "WorldspacePlayback": true
      }
    ],
    "Children": []
  }
]