iter6 depth-tested multi-draw probe — captured 2026-05-19 on ohm
(PineTab2 v2.0, RK3566, Mali-G52 r1 MC1, Mesa 26.0.6, kernel 7.0.0-danctnix1-6)

Source: panvk-bifrost/iter6/{probe_depth.c, .vert, .frag, Makefile}
Deployed to: /tmp/panvk-iter6/

===== RUN #1 (baseline) =====
[step] vkCreateInstance
WARNING: panvk is not a conformant Vulkan implementation, testing use only.
[info] gpu='Mali-G52 r1 MC1'
[info] D32_SFLOAT optimalTilingFeatures=0xd601
[step] vkCreateDevice
[step] vkCreateBuffer vertex buffer
[step] vkCreateImage color attachment
[info] color image memReq size=69632 align=4096
[step] vkCreateImage depth attachment (D32_SFLOAT)
[info] depth image memReq size=69632 align=4096
[step] vkCreatePipelineLayout + shaders
[step] vkCreateGraphicsPipelines
[step] record cmd buffer (2 draws with depth)
[step] submit + wait
[step] verify
[chk] (  0,  0) TL         expect=clear got=0x00000000  clear-ok
[chk] (127,127) BR         expect=clear got=0x00000000  clear-ok
[chk] ( 64, 64) center     expect=green got=0xff00ff00  green-ok
[chk] ( 64, 30) above-B    expect=red   got=0xff0000ff  red-ok
[chk] ( 64,100) below-B    expect=red   got=0xff0000ff  red-ok
[info] coverage: red=3850 green=1352 clear=11182 other=0 (total 16384)
[PASS] depth-tested multi-draw works.

===== KEY OBSERVATIONS =====

1. D32_SFLOAT optimalTilingFeatures = 0xd601:
     bit 0  (0x0001) SAMPLED_IMAGE
     bit 9  (0x0200) DEPTH_STENCIL_ATTACHMENT  ✓
     bit 10 (0x0400) BLIT_SRC
     bit 12 (0x1000) SAMPLED_IMAGE_FILTER_LINEAR
     bit 14 (0x4000) TRANSFER_SRC
     bit 15 (0x8000) TRANSFER_DST

2. Memory:
     color image memReq = 69632 (17 pages)  — 16 raw + 1 aux
     depth image memReq = 69632 (17 pages)  — same overhead for D32
     128*128*4 = 65536 = 16 pages raw pixel data

3. Coverage accounting:
     Triangle A (red, large): NDC area 1.28 / 4 = 32% = ~5243 pixels expected
     Triangle B (green, small, inside A): NDC area 0.32 / 4 = 8% = ~1310 pixels expected
     Got: red=3850, green=1352
     Sum non-clear: 5202 ≈ A's total area (B occludes part of A in depth)
     other=0 — no banding, no z-fighting, no interpolation artifacts.

4. Depth test correct:
     Pixel (64, 64) is inside both triangles. B's z=0.3 < A's z=0.7,
     LESS comparison selects B → green wins. Confirmed at (64, 64).

5. No GPU faults, no validation warnings, deterministic across reruns.