D823 - A three-dimensional image is sampled as a host volume

Status: decided Date: 2026-10-13

A guest sample of a three-dimensional image (dim:SQ_RSRC_IMG_3D) translates to a host binding declared Dim3D, sampled at its three address elements - across, down and deep - as the guest gave them, with no conversion. The texture source it reports says volume, beside cube and compare (D811, D816), and one image read in two shapes is refused as before.

The binding reads the guest's image as a host three-dimensional image of its slices, a command of its own (BindVolumeTexture) beside the flat image and the cube. A linear 8_8_8_8_UNORM volume of one level is read, its slices DEPTH plus one; any other volume binds nothing, and neither does a flat image or a cube under a module that samples three coordinates, so such a draw is refused rather than sampled from an image it does not declare. The slices' layout is measured: a linear 3D image's slices lie one after another at pitch * height, with no padding (obSCEne REQ-20260920T1050Z-5d7c, 20260921-final-eboot.obs.log 16743-16831).

Why: gl2-probe's texture-3d check (GLTP00001) samples a volume, and its refusal stops the command processor, so every check after it reads the clear colour. A volume's coordinates need nothing like a cube's rebuilt direction: the sampler takes them as positions, as the host does.

Rejected:

• Sampling a volume's first slice as a flat image: it answers for one depth only, and the draw would look right where it is wrong.
• A depth-compare of a volume: not translated, as for a cube.