Gaussian splats not applying modelMatrix correctly

[keyboardspecialist]

What happened?

Tiled assets using the glTF and tileset transforms are rendered in their correct positions on the globe. However, rotating the tileset using the modelMatrix rotates the tileset seemingly about the origin of the globe rather than the local asset origin. Simple xyz translations appear to work as expected.

Reproduction steps

1. Open included sandcastle and see that the GS asset is rendered correctly.
2. Click "Rotate" button. Asset is now positioned in an unexpected position.

Sandcastle example

https://sandcastle.cesium.com/#c=jVTbbts4EP0VwlgUMmDQ13aTXSfY1EkDeX1pbDlIDD2UpmiLDUUqJOVbkX8vKcpZOcmmhR/k4Zw5M2dmyB5RNEugLziMyBJlTF9gTJQKxAPh4AyEFbLrx4trTMe078/2fnNEfeXzyUfc8z/5D+ndba9/Cg3oMbp+MCB/e9/6Eo9afnM+bcbzZNYZBDed4fVMjy/78T1t7EbBsDm/vGqNWn06DDAd9Prp3JANg5vNKFg1rX1/d0PH36/ao+BqNw7wbnz55RS2VyL9vl3qj+NHvdmvZ5PWvj2Yyzvdw4+LxdfGycm/uDOYpUwMw8rfIceCKw3WlGyINFI42YCek3ubn3lhBed2T3CNKCcyrFRNXMgZ0UBTRhTRxtZyB36EHByODBfaIKoPbO7TvgycGy6lSExDL5Qx/Mhrd07/7LQbNcsR6ogsstU0FhublHD9WWQ8onx1K1iWkL+AlhmphfzJFgKK4qHChBOYSppQTddEQRRFXlGNA7qCCvheiCQQZYCF1OvgIk3ZDuiYgGLYQOkdI4AugYkmW6q0slDXObLVEimjtiCCyCqC7jjPauI8+wWHVhha08fIc5gq+PDhHTekgv8G5LCYU1tq1YKrbhzPA4FOxdGIy0PJI/+XMVfyZFoOMNI4Bh6RUsgih+2EYAQysSrODfzJNnSKeISR0sZpphEIwRZIfs60Ftws1lCsSVipgWXGsTYpgVci1CAViubHxzUjqc0/xNtes1EzP1db4R0iLem2AxNTOTVzPMwXJiIizHlrL8F2FwOJuGLI5vMOias18EZ4Ls7ty68EToRG+j2J0gKcxKOa2nlNk8J75/3njKEWExQZ/cprnjSqTv0xW+clXeeIzjvgDkvvoksSX8c/9/N4p8pddZ7nGgq7NLmCy3Prad+M1ywmc8kqX+/X9/V48b798eMNvqdvxbgqtUo3vwHnri4A/qFJKqQGmWQehHVNktTMn6j6IsMPhgUr5bIA0K2XQ7sRXQManb3xMgLMzP03nmXG2JTuzezPu3WDfxXKBLIv2nhNJEM7C4ub5wN3CCHs1o35dqR2S/aC+Sc

Environment

Browser: Chrome
CesiumJS Version: 1.130
Operating System: Linux

[javagl]

It does not always happen, and I have not yet identified the exact conditions for when it happens, but it may be related enough to be worth mentioning here: Sometimes, the movement is not picked up by the splat primitive unless the camera is moved:

[keyboardspecialist]

It does not always happen, and I have not yet identified the exact conditions for when it happens, but it may be related enough to be worth mentioning here: Sometimes, the movement is not picked up by the splat primitive unless the camera is moved:

Indeed. The coming PR for this addresses this issue. Simply needed to mark our primitive dirty when the modelMatrix updated.