TerrainModernRenderer records through IGpuPassEncoder instead of calling GL
directly. V4d-1 already converged its two matrix uniforms; this is the plumbing.
What moved. The per-frame indirect command array became an
IGpuFrame.AllocateRing slice, which retires the three-deep per-frame-slot
indirect buffer pool outright. That pool existed so a second terrain draw within
one frame - a retail outside view can issue several - could not overwrite an
earlier draw's still-pending commands; the frame ring gives that structurally,
because every allocation within a frame is distinct memory that lives until the
frame retires. DynamicIndirectBufferCount now reports 0, which is the truth
rather than a silent change.
The vertex and index arena became an IGpuBuffer pair. AddLandblock's two
BufferSubData calls are Upload, and EnsureCapacity's grow-and-copy is
IGpuBuffer.CopyTo, still device-side so resident landblock meshes never
round-trip through system memory. The global VAO is gone: the pipeline owns one
shaped by the vertex layout, and the encoder re-issues attribute pointers on
every BindVertexBuffer.
Locations 2-5 use GpuVertexFormat.UByte4UInt, added at c7f5f251 for exactly
this. They are uvec4 in the shader and carry terrain-type, road and
split-direction codes; UByte4Normalized would have delivered [0,1] floats to an
integer input, which GL leaves undefined - garbage, not an approximation.
uTextureIndexA/uTextureIndexB became GpuPushConstants.TextureIndexA/B. Slice V2b
named those uniforms to match the pinned block, so this was the rename it was
meant to be. uTexTiling moved from a loose uniform float[36] into a std140 block
at GpuBindingModel.UniformTerrainTiling: at 144 bytes of payload it cannot ride
in the 96-byte push-constant block, and no RHI verb sets a uniform array. std140
pads each element to 16 bytes so the block is 576, but the element type is
unchanged, so uTexTiling[int(layer)] reads exactly as before. It is a long-lived
uniform buffer uploaded on the first draw, preserving the upload-once property
the linked-program uniform had.
The imperative Enable(CullFace)/CullFace(Back)/FrontFace(Ccw) triple and the
inherited depth state are baked into one pipeline. Depth compare is GL_LESS, not
the contract's LessOrEqual default: the world frame runs under GL_LESS
(RenderFrameGlStateController.RestoreFrameDefaults) and terrain never called
glDepthFunc, so it inherited it. Baking LessOrEqual would change which of two
coplanar retail surfaces wins - visible exactly where terrain meets roads and
building footings, which is what the shader's zFightTerrainAdjust nudge is
about. Blend off, alpha-to-coverage off, colour write on and depth write on come
from the same frame default, each checked against what terrain observes rather
than assumed. GL_MULTISAMPLE is untouched by pipeline binds, so MSAA does not
leak away from the still-raw-GL sky and particles.
Deliberately unmoved. The terrain clip UBO at binding 2 and the SceneLighting
UBO at binding 1 stay raw global binds - ClipFrame owns one and the viewport and
portal renderers read the other, and both are raw GL until V4h (campaign doc
5.3). The interim GlBindlessHandleTable stays, now held as an IGpuBuffer and
bound through the encoder at binding 9; retiring it is V4t. glMemoryBarrier
stays a raw call: it has no RHI verb and was already a no-op against
client-side uploads. The trailing FrontFace(CW)/Disable(CullFace) restore stays
so sky and particles see what they see today. TerrainAtlas is untouched - it
belongs to V4t. Terrain has no GPU timer to port; its diagnostics use a CPU
stopwatch.
Three consequences worth naming rather than leaving to be discovered.
The convenience constructor narrowed from public to internal, because IGpuDevice
and ICurrentGpuFrameSource are internal RHI types and a public constructor
cannot name them. The class stays public, no other member changed visibility,
and every caller was already in this assembly - EnvCellRenderer's constructor is
internal for the same reason. That is the only visibility change in the diff.
Terrain no longer needs a Shader composed for it, since its pipeline compiles
terrain_modern from the same sources with the same shared preamble. That removes
the terrain-shader composition step, its publication, its lifetime field and the
WorldRenderCompositionPoint member. Two data-driven test cases went with it: one
InlineData row naming "terrain shader" as a publication to fail, and one case
from the theory that enumerates every composition point. App tests therefore
read 3,844 rather than the 3,846 baseline. No invariant lost coverage - both
theories still exercise every remaining resource and point; the two cases were
parameterisations over a step that no longer exists.
The renderer's own GpuRetirementLedger is gone. Every resource it held retryable
releases for is an IGpuBuffer or IGpuPipeline now, and their Dispose already
routes the physical free through the device's retirement queue. Only the
fallback clip UBO is still a raw GL name, so it is all the dispose ledger
carries. The slot allocator's separate retryable publication path is untouched.
Also dropped: a dead BindlessSupport field, assigned and never read.
Gates. Release build green with TreatWarningsAsErrors. App tests 3,844 passed /
3 skipped over four consecutive runs. Offline pixel gate against 0cb10597: 20
differing pixels of 563,200 (fraction 3.55e-05, 28x under the threshold),
against a same-commit control at this commit of 26 - the change differs from its
parent by LESS than the capture differs from itself, which is as close to proof
of no systematic shift as this gate can give. Compared against all three V4d-1
captures the numbers are 20, 32 and 34, against a same-commit V4d-1 spread of 8,
27 and 28: the same distribution. The gate run's client log has zero exceptions
and an empty stderr.
Coverage gap, stated rather than assumed: the offline gate's scene is a fixed
outdoor view. It exercises terrain heavily - terrain blending, road overlays and
the water edge are most of the frame - but it does not cover terrain seen
through a doorway clip region, which is the one terrain path with its own
binding (the clip UBO at binding 2). That wants a user visual check.
No divergence-register row: this slice changes no retail-facing behaviour.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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