[BUG-232929] [PBR] - Textures with alpha channels render wildly different in new PBR test viewer

[sl-service-account]

What just happened?

Upon testing the new PBR materials in the newly released project viewer, I noticed my products do not appear as they previously used to. All textures with alpha channels vary wildly from their current correct state. In my case they are a lot more solid. I am aware that this is likely due to the color space being changed from sRGB to Linear, but the differences aren't subtle, nor are they predictable. This change is also going to break a lot of existing content. It's worth noting that as of yet I haven't been able to reproduce the exact visual quality textures with alpha channels take on in this new PBR viewer in Blender EEVEE. EEVEE is a realtime PBR engine, and as such the results should be the same.

What were you doing when it happened?

Testing what the color space change from sRGB to Linear would entail. But other than that I was just observing, I made no changes to the objects.

What were you expecting to happen instead?

I expected backwards compatilbity with 19 years worth of existing content. I don't think it's acceptable that content has the potential to change this much. This affects all textures with alpha channels, not just my somewhat niche usage case.

This will affect and or break a lot of current existing content, anything that uses textures with alpha channels will be affected. Things such as hair, furniture, clothing, mesh heads and bodies and the list goes on. One example is mesh heads: lots of mesh heads use HD layers for eyebrows/makeup. These layers don't use BOM, they use textures with alpha channels instead (kind of how heads used to work before BOM). These will render differently, and from my testing this will be most visible on darker skintones.

Other information

In my tests, I observed the house as is (rezzed from a folder) in the release viewer, observed it as is in the pbr viewer, and lastly applied a pbr material with the same alpha texture to the same surface. All results looked different.

I also tested the same textures side by side on a simple prim cube.

Attachments

• box test - gltf pbr alpha - aditi.png 2022-11-14 20:35:39
• house gltf pbr alpha viewer, legacy surface.png 2022-11-14 20:35:39
• house gltf pbr alpha viewer, pbr material.png 2022-11-14 20:35:39
• house release viewer (desired appearance).png 2022-11-14 20:35:39

Original Jira Fields

| Field | Value | | ------------- | ------------- | | Issue | BUG-232929 | | Summary | [PBR] - Textures with alpha channels render wildly different in new PBR test viewer | | Type | Bug | | Priority | Unset | | Status | Accepted | | Resolution | Triaged | | Labels | pbr | | Reporter | onsustore (onsustore) | | Created at | 2022-11-15T01:43:03Z | | Updated at | 2022-11-17T20:28:20Z | ``` { 'Build Id': 'unset', 'Business Unit': ['Platform'], 'Date of First Response': '2022-11-15T13:00:56.911-0600', "Is there anything you'd like to add?": 'In my tests, I observed the house as is (rezzed from a folder) in the release viewer, observed it as is in the pbr viewer, and lastly applied a pbr material with the same alpha texture to the same surface. All results looked different.\r\n\r\nI also tested the same textures side by side on a simple prim cube. ', 'ReOpened Count': 0.0, 'Severity': 'Unset', 'System': 'SL Viewer', 'Target Viewer Version': 'viewer-development', 'What just happened?': "Upon testing the new PBR materials in the newly released project viewer, I noticed my products do not appear as they previously used to. \r\nAll textures with alpha channels vary wildly from their current correct state. In my case they are a lot more solid. I am aware that this is likely due to the color space being changed from sRGB to Linear, but the differences aren't subtle, nor are they predictable. This change is also going to break a lot of existing content. \r\nIt's worth noting that as of yet I haven't been able to reproduce the exact visual quality textures with alpha channels take on in this new PBR viewer in Blender EEVEE. EEVEE is a realtime PBR engine, and as such the results should be the same.", 'What were you doing when it happened?': 'Testing what the color space change from sRGB to Linear would entail. But other than that I was just observing, I made no changes to the objects.', 'What were you expecting to happen instead?': "I expected backwards compatilbity with 19 years worth of existing content. I don't think it's acceptable that content has the potential to change this much. This affects all textures with alpha channels, not just my somewhat niche usage case. \r\n\r\nThis will affect and or break a lot of current existing content, anything that uses textures with alpha channels will be affected. Things such as hair, furniture, clothing, mesh heads and bodies and the list goes on. \r\nOne example is mesh heads: lots of mesh heads use HD layers for eyebrows/makeup. These layers don't use BOM, they use textures with alpha channels instead (kind of how heads used to work before BOM). These will render differently, and from my testing this will be most visible on darker skintones. ", } ```

[sl-service-account]

Dan Linden commented at 2022-11-15T19:00:57Z

Thank you for the report, onsustore!

[sl-service-account]

Dan Linden commented at 2022-11-15T19:18:50Z, updated at 2022-11-15T19:19:05Z

@onsustore, can you tell me where I can see or buy a copy of the house in the photos?

[sl-service-account]

onsustore commented at 2022-11-15T21:28:20Z, updated at 2022-11-15T21:31:06Z

@danlinden I responded inworld!  

[sl-service-account]

Dan Linden commented at 2022-11-15T22:55:43Z

Thank you!