How to set a Attribute in WEBGLPipline with custom offset and stride?

[Seungup]

'[...dataA,...dataB,...dataC]' would like to deliver the attribute values of 'instanceA', 'instanceB', and 'instanceC' offset, strade.

In the case of v8.5.20 version, the value was possible through 'accessor'.

https://github.com/visgl/luma.gl/blob/v8.5.20/modules/webgl/src/classes/vertex-array.js#L334-L336

However, as it was changed to 9.0.0 version, the model changed to request to pipeline.

https://github.com/visgl/luma.gl/blob/v9.0.0-alpha.21/modules/engine/src/lib/model.ts#L131-L135

However, the 'setAttribute' method in the pipeline sets the value based on the buffer type variable provided without referencing or verifying the accessor value in the buffer provided, and sets the offset value to the default value of 0.

https://github.com/visgl/luma.gl/blob/v9.0.0-alpha.21/modules/webgl/src/adapter/resources/webgl-render-pipeline.ts#L90-L112

How can I pass the offset value to pipeline to vertex array object?

Is it right for the user to access the pipeline directly and set up a buffer to use it?

[ibgreen]

@Seungup If I understand your question correctly, it is about how to specify an offset into the buffer when using it as an attribute.

It is true that the Accessor concept is being removed in v9. The main motivation for this change is that WebGPU does not have the same flexibility as WebGL (where attribute parameters can be specified after pipeline creation) and since luma.gl 9.0 API is intended to support both APIs it must observe this limitation, and the accessor concept basically became superfluous.

There is a new type ShaderLayout that contains much of the information that was previously encoded in accessors. work in progress documentation here: https://github.com/visgl/luma.gl/blob/master/docs/api-guide/bindings.md#shader-layout

Also there is a bufferMapping prop on device.createRenderPipeline() which enables specification of buffer interleaving and byte offsets. I need to check to what extend this is implemented in WebGL.

Note to self: byteOffset in WebGPU is is set in the BindGroup rather than during pipeline creation so the luma.gl API could perhaps be a bit more dynamic here.

[Seungup]

There was a part here that I couldn't find. Thank you for your quick and accurate answer! 😄