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CONTRACT-P7 §3.2's `default-color-blit-shape@P7`, retired in three pieces, because one
Fatal was covering three unrelated situations.
The shader pass it guarded is there for ROTATION and nothing else: it can only SAMPLE
its source - sampler2D, a float result, one of two 2D view types - so an RGBA8UI
attachment, a 3D slice or an array layer made it return false. The refusal then fired
EVEN ON A SURFACE WITH NO ROTATION, where the ordinary vkCmdBlitImage arm twenty lines
below would have done the blit and does handle those shapes.
- identity: fall through to that arm;
- a non-identity rotation with a source the pass cannot sample: move the region into an
owned 2D single-sample image of a sampled-float format in the SAME size-compatibility
class and shader-blit that;
- outside the four rotations (a mirror, or a mirror-rotation): decline by name, saying
which transform. Neither arm can express a reflection and this package has no device
that reports one to check a result against.
Reinterpretation is the point for the integer case and GL agrees: glBlitFramebuffer
between an integer and a normalized format is INVALID_OPERATION (4.6 core 18.3.1), so
there is no defined result to be wrong about - only a shape that used to end the session
and now produces the source's bits. For a float source of the wrong view type the copy
is a plain slice extraction and the result is exactly right.
THE RETIREMENT UNCOVERED A REAL BUG, which is the part worth reading. The ordinary blit
arm addressed a 3D source as `{aspect, level, source.layer, 1}` with z 0..1. A 3D image's
slice rides Z; its only subresource is layer 0 - which is how the copy endpoint's
CopyImageSliceMapping and the multisample resolve arm above already address one. So a
blit from slice 1 of a 3D texture read slice 0, out of a layer the image does not have.
It was invisible because that shape hit the Fatal first and never reached the arm: the
new scenario's first run had the scratch arm correct and the fall-through arm wrong in
all four quadrants, which is how it fell out. Both arms agree now.
The scenario's source is slice 1 of a 3D texture - ordinary GL, and exactly the shape the
shader pass cannot sample - with slice 0 filled in a colour that appears in no quadrant,
so a scratch copy that forgot the z origin would still be reading real texels and had to
be made distinguishable. It is registered twice on each arm: plain, taking the identity
fall-through, and under MGITEST_MAGMA_FORCE_DEFAULT_BLIT_SCRATCH, taking the rotated
arm's scratch path on an identity surface, where it must produce THE SAME PIXELS. That
equality is the assertion, and it is the only way the scratch arm is reachable from a
host lane at all: every surface this lane can create reports
VK_SURFACE_TRANSFORM_IDENTITY, as does the Redmi pbuffer this cluster's evidence comes
from. The knob does not fake a rotation - nothing downstream is told the surface turned.
Red once (executed, reverted): with MagmaWireFatal("default-color-blit-shape@P7")
restored, both entries die by that name; without it, 2/2 green.
Gates: integration-magma-split 81 (+2), -spawn 60 (+2), -tcp 62 (+2), 0 red;
ctest -L unit 2410; informational integration-magma-full-split 516, 0 red, 59 skip;
fatal_census green; link_ratchet --assert-monotone unchanged at 186, p7-magma 101;
G1 pull .text 0xa52203, defined-symbol name list identical (30570).
Owed to a device window: the scratch arm's geometry under a REAL ROTATE_90/180/270. The
knob proves it produces the fall-through's pixels on an identity surface, which exercises
every line of it except the rotation constant the vertex shader applies.
WireColorBlit.inc and VulkanRenderer.h are edited outside this package's named file list.
Both belong to this cluster (the colour blit's implementation, and four private
declarations beside the existing blit ones); flagged for the integrator.