Fix/gaussian splat flicker

[BlockCnFuture]

Description

I found that during the period between the completion of new material generation and the completion of the new sorting, the drawCommand used the new materials along with the old sorting results, which caused the flickering issue.

I used a simple method to improve the flickering issue of Gaussian Splat by creating a variable that references the address of the old material to ensure it is not affected by the new material, and after the material is generated, I make sure to update _vertexArray (because the length of _indexes staying the same doesn’t necessarily mean no update is needed).

At the same time, I found that !primitive._gaussianSplatTexture is always true, and I’m not sure if this is intentional. Therefore, for now, I don’t need to consider the impact caused by primitive.gaussianSplatTexture.copyFrom.

cesium/packages/engine/Source/Scene/GaussianSplatPrimitive.js

Line 515 in 52f55d0

if (!primitive._gaussianSplatTexture) {

Issue number and link

Fixes #12662

Testing plan

The flickering issue in Gaussian splatting rendering should be improved.

Author checklist

• I have submitted a Contributor License Agreement
• I have added my name to CONTRIBUTORS.md
• I have updated CHANGES.md with a short summary of my change
• I have performed a self-review of my code

[github-actions]

Thank you for the pull request, @BlockCnFuture! Welcome to the Cesium community!

In order for us to review your PR, please complete the following steps:

• Send in a Contributor License Agreement (CLA)
• Add yourself to the contributors file

Review Pull Request Guidelines to make sure your PR gets accepted quickly.

[BlockCnFuture]

Thank you for the pull request, @BlockCnFuture! Welcome to the Cesium community!

In order for us to review your PR, please complete the following steps:

• Send in a Contributor License Agreement (CLA)
• Add yourself to the contributors file

Review Pull Request Guidelines to make sure your PR gets accepted quickly.

I have signed the CLA.

[BlockCnFuture]

before.mp4

after.mp4

[jjhembd]

Thanks @BlockCnFuture, I can confirm we have a signed CLA for you now.
@keyboardspecialist do you have any thoughts on the approach here?

[keyboardspecialist]

It's a very simple change with visible results. That's always a bonus. The extra texture memory overhead isn't a huge deal.

I would just say it could be a short lived fix given potential changes happening. But that may not factor into this at all.

I'll do some testing, but initially it looks like a good fix.

[ggetz]

@keyboardspecialist Were you able to test this at all? If not, what are the next steps so we can help out?

[keyboardspecialist]

@keyboardspecialist Were you able to test this at all? If not, what are the next steps so we can help out?

Yeah, I tested this and pending the other PR checklist items it's good to go.

[ggetz]

Thanks @keyboardspecialist!

@jjhembd Could you review this PR and ultimately merge once happy?

[BlockCnFuture]

The blank lines in CHANGES.md are likely caused by markdownlint.

[jjhembd]

Thanks @BlockCnFuture! This looks good to me!