D773 - A packed float colour target is drawn in its own format

Status: decided Date: 2026-10-08 known_by: published (Mesa's colour-format mapping and the Vulkan format definitions)

A colour target whose CB_COLOR0_INFO says COLOR_10_11_11, NUMBER_FLOAT, in the standard component order is drawn into a B10G11R11_UFLOAT_PACK32 attachment, through a view of the same format. It is seeded from, and written back to, guest memory four bytes a texel, untouched. Mesa targets R11G11B10_FLOAT at COLOR_10_11_11, and Vulkan's packed format holds the same bits: red in bits 0-10, green in 11-21, blue in 22-31.

A target's encoding is carried with its resource (TargetEncoding: eight-bit UNORM, eight-bit sRGB, or this one) in place of the earlier sRGB flag. It decides the attachment's image format, the format it is drawn through, and the pipelines built for it.

Why: PPSA02664 renders its scene into a 1920x1080 10_11_11 float target, the usual HDR buffer. The executor drew only eight-bit targets, so the draw was refused as "not one a frame can be written back to exactly", and the second submission stopped there.

Rejected:

• Drawing it as R8G8B8A8 and converting on writeback: blending would clamp at one, and a value above one is the point of the format.