FA-10706 / Rendering state / Open access

Stencil operation on depth fail · case 01

A stencil-pass result selects the pass operation without checking depth failure.

Verified by executionVariant 1 · 4 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

A stencil-pass result selects the pass operation without checking depth failure.

VERIFIED REPAIR

Use the stage contract: Select stencil-fail, depth-fail, or pass operation in stencil-then-depth order; failed stencil takes precedence.

Unsuccessful approach: Combining both failures selects stencil-fail instead of the distinct depth-fail operation.

Case contract

Select stencil-fail, depth-fail, or pass operation in stencil-then-depth order; failed stencil takes precedence.

Why this case matters

A deterministic software graphics stage with explicit channel and coordinate conventions; no hardware, device profile or API behavior is inferred.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(stencil_pass, depth_pass, fail, zfail, passed):
    return passed if stencil_pass else fail
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1', solve(*(True, False, 'sf', 'df', 'ok')), 'df')
check('fixture 2', solve(*(False, True, 'sf', 'df', 'ok')), 'sf')
check('fixture 3', solve(*(True, True, 'sf', 'df', 'ok')), 'ok')
check('fixture 4', solve(*(False, False, 'sf', 'df', 'ok')), 'sf')
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
fixture 1	`ok`	`df`	Failed
fixture 2	`sf`	`sf`	Passed
fixture 3	`ok`	`ok`	Passed
fixture 4	`sf`	`sf`	Passed

SHA-256 / f724db3e8670c3ecb9f5b9398ac6d42bc0d1046cf1e25113c1d59bf8ad2a0dda

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(stencil_pass, depth_pass, fail, zfail, passed):
    return fail if not stencil_pass or not depth_pass else passed
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1', solve(*(True, False, 'sf', 'df', 'ok')), 'df')
check('fixture 2', solve(*(False, True, 'sf', 'df', 'ok')), 'sf')
check('fixture 3', solve(*(True, True, 'sf', 'df', 'ok')), 'ok')
check('fixture 4', solve(*(False, False, 'sf', 'df', 'ok')), 'sf')
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
fixture 1	`sf`	`df`	Failed
fixture 2	`sf`	`sf`	Passed
fixture 3	`ok`	`ok`	Passed
fixture 4	`sf`	`sf`	Passed

SHA-256 / 8060d144d1555754e652fcbbe01ba22c01709783654afc5888e6c3c65379dd22

3 / The verified repair

Exit 0

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(stencil_pass, depth_pass, fail, zfail, passed):
    return fail if not stencil_pass else (zfail if not depth_pass else passed)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1', solve(*(True, False, 'sf', 'df', 'ok')), 'df')
check('fixture 2', solve(*(False, True, 'sf', 'df', 'ok')), 'sf')
check('fixture 3', solve(*(True, True, 'sf', 'df', 'ok')), 'ok')
check('fixture 4', solve(*(False, False, 'sf', 'df', 'ok')), 'sf')
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
fixture 1	`df`	`df`	Passed
fixture 2	`sf`	`sf`	Passed
fixture 3	`ok`	`ok`	Passed
fixture 4	`sf`	`sf`	Passed

SHA-256 / 5918f6ca5b6608570f9044506734160e268fb6f2b410cb658e09e7a5b3a6608e

Verification & scope

This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.

Observations recorded using Python 3.12.14 at 2026-09-29T14:38:41.464096+00:00.

Case digest / 619b8eb6e001b881e30beff5e83f1eeca4499b891b2103a9f5ab02482f164c63