Plan §5.5.12 finding 2, measured on the committed SPIR-V rather than inferred:
terrain_modern.vert declared
layout(std140, binding = 2) uniform TerrainClip { ... }
with no ACDREAM_UBO_SET, so under the Vulkan dialect the block landed in set 0
binding 2 — which set 0's layout declares as a STORAGE buffer. Any terrain
pipeline built against the shared pipeline layout was therefore malformed.
Nothing had caught it: GL expands the macro to nothing and keeps its UBO and
SSBO namespaces separate, the shader compiled cleanly for both backends, and no
terrain pipeline has ever been created on Vulkan. sky.vert declares the SAME
block correctly and is the precedent, so this is a one-word omission, not a
numbering question.
spirv-dis on spv/terrain_modern.vert.spv, before and after:
before %372 = OpVariable %_ptr_Uniform__struct_370 Uniform
OpDecorate %372 DescriptorSet 0 / Binding 2
after OpDecorate %372 DescriptorSet 1 / Binding 2
with %_struct_370 = OpTypeStruct %int %_arr_v4float_uint_8 — TerrainClip's
{ int uTerrainClipCount; vec4 uTerrainClipPlanes[8]; } — in both.
The same commit closes §5.5.8's second recorded gap. Set 1's layout declared
only bindings 1 and 3, so it was missing BOTH the terrain clip block and
UniformSkyParams at binding 4, which sky.vert and sky.frag have compiled to
SPIR-V since V6e. Both are now declared, all four dynamic, which is half
Vulkan's guaranteed maxDescriptorSetUniformBuffersDynamic of 8 and is asserted
by the capability gate as before.
Membership and ORDER now come from one predicate — IsDeclaredUniformBinding —
that the layout, the descriptor writes and vkCmdBindDescriptorSets's
dynamic-offset array are all built from, the same shape V6g gave set 0. The
three had been restated separately, which is exactly how a fifth binding would
have gone wrong the same way.
Both gaps were found by hand, months apart, and neither could fail on the
shipping backend. VulkanShaderDescriptorContractTests reads the committed .spv
and asserts the partition instead: every uniform block at a declared set-1
binding, every storage block inside set 0's declared range, every sampled
resource in the one texture table. Checked out against the pre-fix .spv, two of
its four tests fail.
Gates: Release build; App tests 4,090 / 3 skips (4,086 baseline plus four);
strict GL offline pixel gate vs 0ca802cd 3.02e-05 (17 px of 563,200, inside the
documented 9–31 px control band, 33x under threshold) — expected, since GL
executes not one changed statement; one Vulkan composition-host run with
VK_LAYER_KHRONOS_validation proven inserted by the loader at zero errors, zero
warnings and no [shutdown] diagnostic on either stream.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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