D857 - User clip planes are pushed with the draw, not compiled in

Status: assumed Date: 2026-10-14

Amends: D830 - the planes were specialization constants of the mesh module.

A translated mesh module reads the user clip planes (PA_CL_UCP_0 to _5) from the push-constant block at entry: word 4 * plane + axis from offset zero. A mesh module's user data arrives in the draw-data buffer (D718), so the block's geometry half is free, and a mesh pipeline's block carries the planes there when it is bound. The fragment half is the fragment stage's user data, as before. The planes are part of the key a pipeline is kept and batched by, and not of its shape (D856).

Why: a specialization constant is compiled into the device pipeline, so each new set of planes was a new pipeline. Neverball clips its reflections against planes that move with the scene: 38 sets in 20 seconds, and with D856 alone 852 of its 1,226 builds still created a device pipeline. With the planes pushed, 45 did, and it went from 4.4 to 6.5 frames a second.

Rejected:

• A uniform buffer of planes: a further binding for six vectors the push block already has room for in every mesh pipeline.