texture.lock({ level: 0 }): only upload a single mip level if locked explicitly

[liamdon]

texture.lock({ level: 0 }): only upload a single mip level if locked explicitly

[mvaligursky]

• WebGPU is similar, but batch uploads all dirty textures before rendering in WebGPUGraphicsDevice._uploadDirtyTextures. The main reason here is that mimmap generation is done using render passes, and we cannot do those while inside other rendering (render pass).
• Another difference on WebGPU implementation is that we create the empty texture right away, and then can upload to it at any time. WebGL does those operations both at a later stage.
• WebGL upload also has some behaviour where if some mip levels are missing, those are automatically generated. Nothing like this is done on WebGPU (at least at the moment, but I wasn't planning on adding it). On WebGPU, if the user manually uploads mipmaps and some are not specified, the simply contain no data.

[slimbuck]

Hi @liamdon ,

Sorry it's taken so long to get back to you. This part of the engine sorely needs love and it's great to have you onboard!

1. Nope you've not missed anything. We should only re-upload the levels that have changed. I believe re-uploading everything (when only the top level changed) is a bug.

2. Texture upload doesn't happen immediately (check the implementation of texture.upload() - it's just setting dirty flags), but rather it happens on demand at render time (when the texture is about to be used). So a user can update multiple levels of a texture before the actual update is invoked. So tracking the dirty levels would require the use of levelsUpdated. (Also by render/upload time the textures should be unlocked anyway meaning _lockedLevel should always be -1).

3. Actually I would suggest not trying to keep the old behaviour at all. Re-uploading mipmap data that hasn't changed is just wasted effort since the texture won't look any different anyway. I'd suggest keeping the code as simple and straightforward as possible - when mip level isn't specified by caller, it defaults to 0 and that's the only level that gets re-uploaded at render time.

cc @mvaligursky, who might have some things to add especially from restrictions on the WebGPU side.

[slimbuck]

Nice, thanks.

Fortunately most of these differences are hidden inside the respective platform implementations (webgl-texture, webgl-device, webgpu-texture etc).

In terms of this public texture API, do you see any potential issues @mvaligursky?

[mvaligursky]

Nope, the API suggestions sound great. Even though it probably not hurt to refactor the WebglTexture class a bit to make it more flexible, before implementing the changes - to make the code easier to follow.

[mvaligursky]

related ticket: #4290