Mesh with blendshapes flickers explosion shapes when there exists other mesh instance

[FancyToday]

Godot version

3.4.2stable and 3.5beta

System information

Windows10, i7-1165G7, Intel(R) Iris(R) Xe Graphics, GLES3

Issue description

After importing a glb model into a scene, if the model has multiple mesh instances and at least one mesh instance has blendshapes than the scene will continuously flicker explode fragment shapes.
To avoid this problem, either to turn off the visiblility of mesh with blendshapes or to turn off all the other mesh instances.
May strongly related to the hardware because we don't have this problem on other types of GPU platforms.

1. Normal( in other PC with HD520)
   
2. display abnormal in the running window
   

Steps to reproduce

Import a glb model with multiple mesh instances and at least one of the mesh instances has blendshapes into a scene.
And rotate or zoom it in the scene.

Minimal reproduction project

Later I will upload...

[Calinou]

@FancyToday Please upload a minimal reproduction project to make this easier to troubleshoot.

May strongly related to the hardware because we don't have this problem on other types of GPU platforms.

What GPUs did you test this with?

[smix8]

There are two everylasting issues with blendshape meshes and shared instances or mesh resource threaded loading in Godot 3.x so might be one of the two.

a) blendshape values are not (re)set properly when the mesh joins the scene, happens constantly with threading, result is that mesh explodes. You can try to (hard)reset all blendvalues to e.g. 0.0 in a script and see if this solves the issue.

b) mesh is shared with other instances and not made unique / local to scene. This is not a bug just how Godot roles with blendshapes. As soon as two instances have different blendvalues corruption sets in. You can try to duplicate / local_to_scene the mesh for each instance and see if this solves the issue.

[JDMeta]

There are two everylasting issues with blendshape meshes and shared instances or mesh resource threaded loading in Godot 3.x so might be one of the two.

a) blendshape values are not (re)set properly when the mesh joins the scene, happens constantly with threading, result is that mesh explodes. You can try to (hard)reset all blendvalues to e.g. 0.0 in a script and see if this solves the issue.

b) mesh is shared with other instances and not made unique / local to scene. This is not a bug just how Godot roles with blendshapes. As soon as two instances have different blendvalues corruption sets in. You can try to duplicate / local_to_scene the mesh for each instance and see if this solves the issue.

a) I have tried to set the blendvalue to 0 but the problem is still there.
func _ready(): $Armature/Skeleton/Head.set("blend_shapes/EyeBlink_L", 0)
b)Tried to make all mesh instance local_to_scene, but it is still not working.
Please take a look at this problem on GPU Intel(R) Iris(R) Xe Graphics if available because we don't have this problem on other GPU for now.

[JDMeta]

@FancyToday Please upload a minimal reproduction project to make this easier to troubleshoot.

May strongly related to the hardware because we don't have this problem on other types of GPU platforms.

What GPUs did you test this with?

Intel(R) Iris(R) Xe Graphics

[JDMeta]

Can you reproduce this problem on certain GPU? Please take a look at this issue. It is really important to our project. Thank you!

[Calinou]

Can you reproduce this problem on certain GPU? Please take a look at this issue. It is really important to our project. Thank you!

Sorry, most contributors (myself included) don't have access to this GPU. This will take a while to be fixed, if ever. Switching to the GLES2 renderer may alleviate this issue.

There's also no minimal reproduction project uploaded yet, and no way for anyone to reproduce this issue locally on a specified project.

[yuhuixu1993]

Can you reproduce this problem on certain GPU? Please take a look at this issue. It is really important to our project. Thank you!

Sorry, most contributors (myself included) don't have access to this GPU. This will take a while to be fixed, if ever. Switching to the GLES2 renderer may alleviate this issue.

There's also no minimal reproduction project uploaded yet, and no way for anyone to reproduce this issue locally on a specified project.

I came up with the similar problem. Intel(R) Iris(R) Xe Graphics, such GPU is quite popular in windows laptops. Hoping solutions to this issue!

[JDMeta]

Can you reproduce this problem on certain GPU? Please take a look at this issue. It is really important to our project. Thank you!

Sorry, most contributors (myself included) don't have access to this GPU. This will take a while to be fixed, if ever. Switching to the GLES2 renderer may alleviate this issue.

There's also no minimal reproduction project uploaded yet, and no way for anyone to reproduce this issue locally on a specified project.

GLES2 is OK but our project needs GLES3. We will upload minimal project ASAP. Thanks!

[MJacred]

Switching to the GLES2 renderer may alleviate this issue.

According to the documentation, blendshapes are not supported in GLES2: https://docs.godotengine.org/en/stable/tutorials/rendering/gles2_gles3_differences.html#blend-shapes.

Or are the docs outdated?

EDIT: ok, the docs are outdated: #48480; opened a PR to update docs: godotengine/godot-docs#5954