Function lower_encoded_external 

pub fn lower_encoded_external(entry: &EncodedExternalTexture) -> GpuEncodedPaint

Lower one encoded external texture into the record the strip shader samples.

The external counterpart of super::atlas::lower_encoded_image, and the same record type: the shader reads both through one GpuEncodedImage layout and picks the binding from the source-kind bit pack_image_params sets here. What differs is where the numbers come from — the source region is the caller’s own texel rectangle rather than an atlas allocation, there is no atlas layer to name (hence the zero index, which the shader never reads on this path) and no padding, since nothing was packed beside it.

The transform is already the inverse mapping — device space into texel space — because that is the direction the shader applies it in; narrowing it to f32 here is what the record and the WGSL both read it at.